diff --git a/packages/@rescript/runtime/Belt_Array.res b/packages/@rescript/runtime/Belt_Array.res
index ea7c76a86c6..dc1003d273f 100644
--- a/packages/@rescript/runtime/Belt_Array.res
+++ b/packages/@rescript/runtime/Belt_Array.res
@@ -15,8 +15,6 @@ external getUnsafe: (t<'a>, int) => 'a = "%array_unsafe_get"
 
 external setUnsafe: (t<'a>, int, 'a) => unit = "%array_unsafe_set"
 
-external getUndefined: (t<'a>, int) => Js.undefined<'a> = "%array_unsafe_get"
-
 /* external get: 'a t -> int -> 'a = "%array_safe_get" */
 let get = (arr, i) =>
   if i >= 0 && i < length(arr) {
diff --git a/packages/@rescript/runtime/Belt_Array.resi b/packages/@rescript/runtime/Belt_Array.resi
index 1e7969046aa..8f6cac74c56 100644
--- a/packages/@rescript/runtime/Belt_Array.resi
+++ b/packages/@rescript/runtime/Belt_Array.resi
@@ -59,15 +59,6 @@ no bounds checking; this would cause type error if `i` does not stay within rang
 */
 external getUnsafe: (t<'a>, int) => 'a = "%array_unsafe_get"
 
-/**
-`getUndefined(arr, i)`
-
-It does the samething in the runtime as [`getUnsafe`]();
-it is _type safe_ since the return type still track whether it is
-in range or not
-*/
-external getUndefined: (t<'a>, int) => Js.undefined<'a> = "%array_unsafe_get"
-
 /**
 `set(arr, n, x)` modifies `arr` in place; it replaces the nth element of `arr`
 with `x`. Returning `false` means not updated due to out of range.
diff --git a/packages/@rescript/runtime/Belt_Map.res b/packages/@rescript/runtime/Belt_Map.res
index 2840a2e8b23..ed34be5a221 100644
--- a/packages/@rescript/runtime/Belt_Map.res
+++ b/packages/@rescript/runtime/Belt_Map.res
@@ -101,18 +101,12 @@ let toArray = m => Dict.toArray(m.data)
 let keysToArray = m => Dict.keysToArray(m.data)
 let valuesToArray = m => Dict.valuesToArray(m.data)
 let minKey = m => Dict.minKey(m.data)
-let minKeyUndefined = m => Dict.minKeyUndefined(m.data)
 let maxKey = m => Dict.maxKey(m.data)
-let maxKeyUndefined = m => Dict.maxKeyUndefined(m.data)
 let minimum = m => Dict.minimum(m.data)
-let minUndefined = m => Dict.minUndefined(m.data)
 let maximum = m => Dict.maximum(m.data)
-let maxUndefined = m => Dict.maxUndefined(m.data)
 
 let get = (map, x) => Dict.get(~cmp=map.cmp, map.data, x)
 
-let getUndefined = (map, x) => Dict.getUndefined(~cmp=map.cmp, map.data, x)
-
 let getWithDefault = (map, x, def) => Dict.getWithDefault(~cmp=map.cmp, map.data, x, def)
 
 let getOrThrow = (map, x) => Dict.getOrThrow(~cmp=map.cmp, map.data, x)
diff --git a/packages/@rescript/runtime/Belt_Map.resi b/packages/@rescript/runtime/Belt_Map.resi
index fc883223906..78dd3482db0 100644
--- a/packages/@rescript/runtime/Belt_Map.resi
+++ b/packages/@rescript/runtime/Belt_Map.resi
@@ -295,27 +295,15 @@ let valuesToArray: t<'k, 'v, 'id> => array<'v>
 /** `minKey(s)` returns the minimum key, None if not exist. */
 let minKey: t<'k, _, _> => option<'k>
 
-/** See `Belt.Map.minKey` */
-let minKeyUndefined: t<'k, _, _> => Js.undefined<'k>
-
 /** `maxKey(s)` returns the maximum key, None if not exist. */
 let maxKey: t<'k, _, _> => option<'k>
 
-/** See `Belt.Map.maxKey` */
-let maxKeyUndefined: t<'k, _, _> => Js.undefined<'k>
-
 /** `minimum(s)` returns the minimum key value pair, None if not exist. */
 let minimum: t<'k, 'v, _> => option<('k, 'v)>
 
-/** See `Belt.Map.minimum` */
-let minUndefined: t<'k, 'v, _> => Js.undefined<('k, 'v)>
-
 /** `maximum(s)` returns the maximum key value pair, None if not exist. */
 let maximum: t<'k, 'v, _> => option<('k, 'v)>
 
-/** See `Belt.Map.maximum` */
-let maxUndefined: t<'k, 'v, _> => Js.undefined<('k, 'v)>
-
 /** 
  `get(s, k)`
 
@@ -334,9 +322,6 @@ Belt.Map.get(Belt.Map.fromArray([(2, "2"), (1, "1"), (3, "3")], ~id=module(IntCm
 */
 let get: (t<'k, 'v, 'id>, 'k) => option<'v>
 
-/** See `Belt.Map.get`. Returns `undefined` when not found*/
-let getUndefined: (t<'k, 'v, 'id>, 'k) => Js.undefined<'v>
-
 /** 
 `getWithDefault(s, k, default)`
 
diff --git a/packages/@rescript/runtime/Belt_MapDict.res b/packages/@rescript/runtime/Belt_MapDict.res
index 1a751264fab..229ad0e37d1 100644
--- a/packages/@rescript/runtime/Belt_MapDict.res
+++ b/packages/@rescript/runtime/Belt_MapDict.res
@@ -34,12 +34,7 @@ let minimum = N.minimum
 let maximum = N.maximum
 let minKey = N.minKey
 let maxKey = N.maxKey
-let minKeyUndefined = N.minKeyUndefined
-let maxKeyUndefined = N.maxKeyUndefined
-let minUndefined = N.minUndefined
-let maxUndefined = N.maxUndefined
 let get = N.get
-let getUndefined = N.getUndefined
 let getWithDefault = N.getWithDefault
 let getOrThrow = N.getOrThrow
 let getExn = getOrThrow
diff --git a/packages/@rescript/runtime/Belt_MapDict.resi b/packages/@rescript/runtime/Belt_MapDict.resi
index cfff7c39754..a9b50a30f80 100644
--- a/packages/@rescript/runtime/Belt_MapDict.resi
+++ b/packages/@rescript/runtime/Belt_MapDict.resi
@@ -115,24 +115,14 @@ let valuesToArray: t<'k, 'a, 'id> => array<'a>
 
 let minKey: t<'k, _, _> => option<'k>
 
-let minKeyUndefined: t<'k, _, _> => Js.undefined<'k>
-
 let maxKey: t<'k, _, _> => option<'k>
 
-let maxKeyUndefined: t<'k, _, _> => Js.undefined<'k>
-
 let minimum: t<'k, 'a, _> => option<('k, 'a)>
 
-let minUndefined: t<'k, 'a, _> => Js.undefined<('k, 'a)>
-
 let maximum: t<'k, 'a, _> => option<('k, 'a)>
 
-let maxUndefined: t<'k, 'a, _> => Js.undefined<('k, 'a)>
-
 let get: (t<'k, 'a, 'id>, 'k, ~cmp: cmp<'k, 'id>) => option<'a>
 
-let getUndefined: (t<'k, 'a, 'id>, 'k, ~cmp: cmp<'k, 'id>) => Js.undefined<'a>
-
 let getWithDefault: (t<'k, 'a, 'id>, 'k, 'a, ~cmp: cmp<'k, 'id>) => 'a
 
 let getExn: (t<'k, 'a, 'id>, 'k, ~cmp: cmp<'k, 'id>) => 'a
diff --git a/packages/@rescript/runtime/Belt_MapInt.res b/packages/@rescript/runtime/Belt_MapInt.res
index 2ce7d0d151c..08e2b5486b0 100644
--- a/packages/@rescript/runtime/Belt_MapInt.res
+++ b/packages/@rescript/runtime/Belt_MapInt.res
@@ -11,13 +11,9 @@ let isEmpty = N.isEmpty
 /* let singleton = N.singleton */
 
 let minKey = N.minKey
-let minKeyUndefined = N.minKeyUndefined
 let maxKey = N.maxKey
-let maxKeyUndefined = N.maxKeyUndefined
 let minimum = N.minimum
-let minUndefined = N.minUndefined
 let maximum = N.maximum
-let maxUndefined = N.maxUndefined
 let findFirstBy = N.findFirstBy
 let forEach = N.forEach
 let map = N.map
@@ -169,7 +165,6 @@ let has = I.has
 let cmp = I.cmp
 let eq = I.eq
 let get = I.get
-let getUndefined = I.getUndefined
 let getWithDefault = I.getWithDefault
 let getOrThrow = I.getOrThrow
 let getExn = getOrThrow
diff --git a/packages/@rescript/runtime/Belt_MapInt.resi b/packages/@rescript/runtime/Belt_MapInt.resi
index aa71c5e1c2e..42b2e1de683 100644
--- a/packages/@rescript/runtime/Belt_MapInt.resi
+++ b/packages/@rescript/runtime/Belt_MapInt.resi
@@ -92,24 +92,14 @@ let valuesToArray: t<'v> => array<'v>
 
 let minKey: t<_> => option<key>
 
-let minKeyUndefined: t<_> => Js.undefined<key>
-
 let maxKey: t<_> => option<key>
 
-let maxKeyUndefined: t<_> => Js.undefined<key>
-
 let minimum: t<'v> => option<(key, 'v)>
 
-let minUndefined: t<'v> => Js.undefined<(key, 'v)>
-
 let maximum: t<'v> => option<(key, 'v)>
 
-let maxUndefined: t<'v> => Js.undefined<(key, 'v)>
-
 let get: (t<'v>, key) => option<'v>
 
-let getUndefined: (t<'v>, key) => Js.undefined<'v>
-
 let getWithDefault: (t<'v>, key, 'v) => 'v
 
 let getExn: (t<'v>, key) => 'v
diff --git a/packages/@rescript/runtime/Belt_MapString.res b/packages/@rescript/runtime/Belt_MapString.res
index af592d6c2c3..9f1cbb4e348 100644
--- a/packages/@rescript/runtime/Belt_MapString.res
+++ b/packages/@rescript/runtime/Belt_MapString.res
@@ -11,13 +11,9 @@ let isEmpty = N.isEmpty
 /* let singleton = N.singleton */
 
 let minKey = N.minKey
-let minKeyUndefined = N.minKeyUndefined
 let maxKey = N.maxKey
-let maxKeyUndefined = N.maxKeyUndefined
 let minimum = N.minimum
-let minUndefined = N.minUndefined
 let maximum = N.maximum
-let maxUndefined = N.maxUndefined
 let findFirstBy = N.findFirstBy
 let forEach = N.forEach
 let map = N.map
@@ -169,7 +165,6 @@ let has = I.has
 let cmp = I.cmp
 let eq = I.eq
 let get = I.get
-let getUndefined = I.getUndefined
 let getWithDefault = I.getWithDefault
 let getOrThrow = I.getOrThrow
 let getExn = getOrThrow
diff --git a/packages/@rescript/runtime/Belt_MapString.resi b/packages/@rescript/runtime/Belt_MapString.resi
index 0456a745114..0469496376e 100644
--- a/packages/@rescript/runtime/Belt_MapString.resi
+++ b/packages/@rescript/runtime/Belt_MapString.resi
@@ -92,24 +92,14 @@ let valuesToArray: t<'v> => array<'v>
 
 let minKey: t<_> => option<key>
 
-let minKeyUndefined: t<_> => Js.undefined<key>
-
 let maxKey: t<_> => option<key>
 
-let maxKeyUndefined: t<_> => Js.undefined<key>
-
 let minimum: t<'v> => option<(key, 'v)>
 
-let minUndefined: t<'v> => Js.undefined<(key, 'v)>
-
 let maximum: t<'v> => option<(key, 'v)>
 
-let maxUndefined: t<'v> => Js.undefined<(key, 'v)>
-
 let get: (t<'v>, key) => option<'v>
 
-let getUndefined: (t<'v>, key) => Js.undefined<'v>
-
 let getWithDefault: (t<'v>, key, 'v) => 'v
 
 let getExn: (t<'v>, key) => 'v
diff --git a/packages/@rescript/runtime/Belt_MutableMap.res b/packages/@rescript/runtime/Belt_MutableMap.res
index 87779759dce..2ad66f79be4 100644
--- a/packages/@rescript/runtime/Belt_MutableMap.res
+++ b/packages/@rescript/runtime/Belt_MutableMap.res
@@ -136,13 +136,9 @@ let clear = m => m.data = None
 let isEmpty = d => N.isEmpty(d.data)
 
 let minKey = m => N.minKey(m.data)
-let minKeyUndefined = m => N.minKeyUndefined(m.data)
 let maxKey = m => N.maxKey(m.data)
-let maxKeyUndefined = m => N.maxKeyUndefined(m.data)
 let minimum = m => N.minimum(m.data)
-let minUndefined = m => N.minUndefined(m.data)
 let maximum = m => N.maximum(m.data)
-let maxUndefined = m => N.maxUndefined(m.data)
 
 let forEach = (d, f) => N.forEach(d.data, f)
 let reduce = (d, acc, cb) => N.reduce(d.data, acc, cb)
@@ -168,8 +164,6 @@ let map = (m, f) => {cmp: m.cmp, data: N.map(m.data, f)}
 let mapWithKey = (m, f) => {cmp: m.cmp, data: N.mapWithKey(m.data, f)}
 let get = (m, x) => N.get(~cmp=m.cmp, m.data, x)
 
-let getUndefined = (m, x) => N.getUndefined(~cmp=m.cmp, m.data, x)
-
 let getWithDefault = (m, x, def) => N.getWithDefault(~cmp=m.cmp, m.data, x, def)
 
 let getOrThrow = (m, x) => N.getOrThrow(~cmp=m.cmp, m.data, x)
diff --git a/packages/@rescript/runtime/Belt_MutableMap.resi b/packages/@rescript/runtime/Belt_MutableMap.resi
index 598d587a793..106d7ac9e8c 100644
--- a/packages/@rescript/runtime/Belt_MutableMap.resi
+++ b/packages/@rescript/runtime/Belt_MutableMap.resi
@@ -92,15 +92,10 @@ let fromArray: (array<('k, 'a)>, ~id: id<'k, 'id>) => t<'k, 'a, 'id>
 let keysToArray: t<'k, _, _> => array<'k>
 let valuesToArray: t<_, 'a, _> => array<'a>
 let minKey: t<'k, _, _> => option<'k>
-let minKeyUndefined: t<'k, _, _> => Js.undefined<'k>
 let maxKey: t<'k, _, _> => option<'k>
-let maxKeyUndefined: t<'k, _, _> => Js.undefined<'k>
 let minimum: t<'k, 'a, _> => option<('k, 'a)>
-let minUndefined: t<'k, 'a, _> => Js.undefined<('k, 'a)>
 let maximum: t<'k, 'a, _> => option<('k, 'a)>
-let maxUndefined: t<'k, 'a, _> => Js.undefined<('k, 'a)>
 let get: (t<'k, 'a, 'id>, 'k) => option<'a>
-let getUndefined: (t<'k, 'a, 'id>, 'k) => Js.undefined<'a>
 let getWithDefault: (t<'k, 'a, 'id>, 'k, 'a) => 'a
 let getExn: (t<'k, 'a, 'id>, 'k) => 'a
 let getOrThrow: (t<'k, 'a, 'id>, 'k) => 'a
diff --git a/packages/@rescript/runtime/Belt_MutableMapInt.res b/packages/@rescript/runtime/Belt_MutableMapInt.res
index 9f0209a523c..d48571cf566 100644
--- a/packages/@rescript/runtime/Belt_MutableMapInt.res
+++ b/packages/@rescript/runtime/Belt_MutableMapInt.res
@@ -11,14 +11,10 @@ let isEmpty = m => N.isEmpty(m.data)
 let clear = m => m.data = None
 /* let singleton k v = t ~data:(N.singleton k v) */
 
-let minKeyUndefined = m => N.minKeyUndefined(m.data)
 let minKey = m => N.minKey(m.data)
-let maxKeyUndefined = m => N.maxKeyUndefined(m.data)
 let maxKey = m => N.maxKey(m.data)
 let minimum = m => N.minimum(m.data)
-let minUndefined = m => N.minUndefined(m.data)
 let maximum = m => N.maximum(m.data)
-let maxUndefined = m => N.maxUndefined(m.data)
 
 let set = (m: t<_>, k, v) => {
   let old_data = m.data
@@ -163,7 +159,6 @@ let cmp = (d0, d1, f) => I.cmp(d0.data, d1.data, f)
 let eq = (d0, d1, f) => I.eq(d0.data, d1.data, f)
 
 let get = (d, x) => I.get(d.data, x)
-let getUndefined = (d, x) => I.getUndefined(d.data, x)
 let getWithDefault = (d, x, def) => I.getWithDefault(d.data, x, def)
 let getOrThrow = (d, x) => I.getOrThrow(d.data, x)
 let getExn = getOrThrow
diff --git a/packages/@rescript/runtime/Belt_MutableMapInt.resi b/packages/@rescript/runtime/Belt_MutableMapInt.resi
index a1b5acccb93..cc588d991c3 100644
--- a/packages/@rescript/runtime/Belt_MutableMapInt.resi
+++ b/packages/@rescript/runtime/Belt_MutableMapInt.resi
@@ -77,15 +77,10 @@ let fromArray: array<(key, 'a)> => t<'a>
 let keysToArray: t<'a> => array<key>
 let valuesToArray: t<'a> => array<'a>
 let minKey: t<_> => option<key>
-let minKeyUndefined: t<_> => Js.undefined<key>
 let maxKey: t<_> => option<key>
-let maxKeyUndefined: t<_> => Js.undefined<key>
 let minimum: t<'a> => option<(key, 'a)>
-let minUndefined: t<'a> => Js.undefined<(key, 'a)>
 let maximum: t<'a> => option<(key, 'a)>
-let maxUndefined: t<'a> => Js.undefined<(key, 'a)>
 let get: (t<'a>, key) => option<'a>
-let getUndefined: (t<'a>, key) => Js.undefined<'a>
 let getWithDefault: (t<'a>, key, 'a) => 'a
 let getExn: (t<'a>, key) => 'a
 let getOrThrow: (t<'a>, key) => 'a
diff --git a/packages/@rescript/runtime/Belt_MutableMapString.res b/packages/@rescript/runtime/Belt_MutableMapString.res
index 8d1a38d4ca0..5aeccb68ca0 100644
--- a/packages/@rescript/runtime/Belt_MutableMapString.res
+++ b/packages/@rescript/runtime/Belt_MutableMapString.res
@@ -11,14 +11,10 @@ let isEmpty = m => N.isEmpty(m.data)
 let clear = m => m.data = None
 /* let singleton k v = t ~data:(N.singleton k v) */
 
-let minKeyUndefined = m => N.minKeyUndefined(m.data)
 let minKey = m => N.minKey(m.data)
-let maxKeyUndefined = m => N.maxKeyUndefined(m.data)
 let maxKey = m => N.maxKey(m.data)
 let minimum = m => N.minimum(m.data)
-let minUndefined = m => N.minUndefined(m.data)
 let maximum = m => N.maximum(m.data)
-let maxUndefined = m => N.maxUndefined(m.data)
 
 let set = (m: t<_>, k, v) => {
   let old_data = m.data
@@ -163,7 +159,6 @@ let cmp = (d0, d1, f) => I.cmp(d0.data, d1.data, f)
 let eq = (d0, d1, f) => I.eq(d0.data, d1.data, f)
 
 let get = (d, x) => I.get(d.data, x)
-let getUndefined = (d, x) => I.getUndefined(d.data, x)
 let getWithDefault = (d, x, def) => I.getWithDefault(d.data, x, def)
 let getOrThrow = (d, x) => I.getOrThrow(d.data, x)
 let getExn = getOrThrow
diff --git a/packages/@rescript/runtime/Belt_MutableMapString.resi b/packages/@rescript/runtime/Belt_MutableMapString.resi
index 9f47a23d3fd..921c52c24b2 100644
--- a/packages/@rescript/runtime/Belt_MutableMapString.resi
+++ b/packages/@rescript/runtime/Belt_MutableMapString.resi
@@ -77,15 +77,10 @@ let fromArray: array<(key, 'a)> => t<'a>
 let keysToArray: t<'a> => array<key>
 let valuesToArray: t<'a> => array<'a>
 let minKey: t<_> => option<key>
-let minKeyUndefined: t<_> => Js.undefined<key>
 let maxKey: t<_> => option<key>
-let maxKeyUndefined: t<_> => Js.undefined<key>
 let minimum: t<'a> => option<(key, 'a)>
-let minUndefined: t<'a> => Js.undefined<(key, 'a)>
 let maximum: t<'a> => option<(key, 'a)>
-let maxUndefined: t<'a> => Js.undefined<(key, 'a)>
 let get: (t<'a>, key) => option<'a>
-let getUndefined: (t<'a>, key) => Js.undefined<'a>
 let getWithDefault: (t<'a>, key, 'a) => 'a
 let getExn: (t<'a>, key) => 'a
 let getOrThrow: (t<'a>, key) => 'a
diff --git a/packages/@rescript/runtime/Belt_MutableQueue.res b/packages/@rescript/runtime/Belt_MutableQueue.res
index 6ed8a1763a5..3912f22629b 100644
--- a/packages/@rescript/runtime/Belt_MutableQueue.res
+++ b/packages/@rescript/runtime/Belt_MutableQueue.res
@@ -54,12 +54,6 @@ let peek = q =>
   | Some(v) => Some(v.content)
   }
 
-let peekUndefined = q =>
-  switch q.first {
-  | None => Js.undefined
-  | Some(v) => Js.Undefined.return(v.content)
-  }
-
 let peekOrThrow = q =>
   switch q.first {
   | None => throw(Not_found)
@@ -85,13 +79,11 @@ let pop = q =>
   }
 
 let popOrThrow = q =>
-  /* TO fix */
   switch q.first {
   | None => throw(Not_found)
   | Some(x) =>
     let next = x.next
     if next == None {
-      /* only one element */
       clear(q)
       x.content
     } else {
@@ -103,22 +95,6 @@ let popOrThrow = q =>
 
 let popExn = popOrThrow
 
-let popUndefined = q =>
-  switch q.first {
-  | None => Js.undefined
-  | Some(x) =>
-    let next = x.next
-    if next == None {
-      /* only one element */
-      clear(q)
-      Js.Undefined.return(x.content)
-    } else {
-      q.length = q.length - 1
-      q.first = next
-      Js.Undefined.return(x.content)
-    }
-  }
-
 let rec copyAux = (qRes, prev, cell) =>
   switch cell {
   | None =>
diff --git a/packages/@rescript/runtime/Belt_MutableQueue.resi b/packages/@rescript/runtime/Belt_MutableQueue.resi
index ef4e542fbaa..d5f5dbefcae 100644
--- a/packages/@rescript/runtime/Belt_MutableQueue.resi
+++ b/packages/@rescript/runtime/Belt_MutableQueue.resi
@@ -43,11 +43,6 @@ let add: (t<'a>, 'a) => unit
 */
 let peek: t<'a> => option<'a>
 
-/**
-`peekUndefined(q)` returns `undefined` if not found.
-*/
-let peekUndefined: t<'a> => Js.undefined<'a>
-
 /**
 `peekExn(q)` throws an exception if `q` is empty.
 */
@@ -63,12 +58,6 @@ let peekOrThrow: t<'a> => 'a
 */
 let pop: t<'a> => option<'a>
 
-/**
-`popUndefined(q)` removes and returns the first element in queue `q`. it will
-return `undefined` if it is already empty.
-*/
-let popUndefined: t<'a> => Js.undefined<'a>
-
 /**
 `popExn(q)` throw an exception if q is empty.
 */
diff --git a/packages/@rescript/runtime/Belt_MutableSet.res b/packages/@rescript/runtime/Belt_MutableSet.res
index c2c54b5e103..f45f1d88757 100644
--- a/packages/@rescript/runtime/Belt_MutableSet.res
+++ b/packages/@rescript/runtime/Belt_MutableSet.res
@@ -184,9 +184,7 @@ let make = (type value identity, ~id: id<value, identity>) => {
 let isEmpty = d => N.isEmpty(d.data)
 
 let minimum = d => N.minimum(d.data)
-let minUndefined = d => N.minUndefined(d.data)
 let maximum = d => N.maximum(d.data)
-let maxUndefined = d => N.maxUndefined(d.data)
 
 let forEach = (d, f) => N.forEach(d.data, f)
 let reduce = (d, acc, cb) => N.reduce(d.data, acc, cb)
@@ -215,8 +213,6 @@ let eq = (d0, d1) => N.eq(~cmp=d0.cmp, d0.data, d1.data)
 
 let get = (d, x) => N.get(~cmp=d.cmp, d.data, x)
 
-let getUndefined = (d, x) => N.getUndefined(~cmp=d.cmp, d.data, x)
-
 let getOrThrow = (d, x) => N.getOrThrow(~cmp=d.cmp, d.data, x)
 
 let getExn = getOrThrow
diff --git a/packages/@rescript/runtime/Belt_MutableSet.resi b/packages/@rescript/runtime/Belt_MutableSet.resi
index 19b1555677a..a8b31510864 100644
--- a/packages/@rescript/runtime/Belt_MutableSet.resi
+++ b/packages/@rescript/runtime/Belt_MutableSet.resi
@@ -530,26 +530,6 @@ s1->Belt.MutableSet.minimum == Some(1)
 */
 let minimum: t<'value, 'id> => option<'value>
 
-/**
-Returns minimum value of the collection. `undefined` if collection is empty.
-
-## Examples
-
-```rescript
-module IntCmp = Belt.Id.MakeComparable({
-  type t = int
-  let cmp = Pervasives.compare
-})
-
-let s0 = Belt.MutableSet.make(~id=module(IntCmp))
-let s1 = Belt.MutableSet.fromArray([3, 2, 1, 5], ~id=module(IntCmp))
-
-s0->Belt.MutableSet.minUndefined == Js.undefined
-s1->Belt.MutableSet.minUndefined == Js.Undefined.return(1)
-```
-*/
-let minUndefined: t<'value, 'id> => Js.undefined<'value>
-
 /**
 Returns maximum value of the collection. `None` if collection is empty.
 
@@ -570,26 +550,6 @@ s1->Belt.MutableSet.maximum == Some(5)
 */
 let maximum: t<'value, 'id> => option<'value>
 
-/**
-Returns maximum value of the collection. `undefined` if collection is empty.
-
-## Examples
-
-```rescript
-module IntCmp = Belt.Id.MakeComparable({
-  type t = int
-  let cmp = Pervasives.compare
-})
-
-let s0 = Belt.MutableSet.make(~id=module(IntCmp))
-let s1 = Belt.MutableSet.fromArray([3, 2, 1, 5], ~id=module(IntCmp))
-
-s0->Belt.MutableSet.maxUndefined == Js.undefined
-s1->Belt.MutableSet.maxUndefined == Js.Undefined.return(5)
-```
-*/
-let maxUndefined: t<'value, 'id> => Js.undefined<'value>
-
 /**
 Returns the reference of the value which is equivalent to value using the comparator specifiecd by this collection. Returns `None` if element does not exist.
 
@@ -609,11 +569,6 @@ s0->Belt.MutableSet.get(20) == None
 */
 let get: (t<'value, 'id>, 'value) => option<'value>
 
-/**
-Same as `Belt.MutableSet.get` but returns `undefined` when element does not exist.
-*/
-let getUndefined: (t<'value, 'id>, 'value) => Js.undefined<'value>
-
 /**
 Same as `Belt.MutableSet.get` but throw when element does not exist.
 */
diff --git a/packages/@rescript/runtime/Belt_MutableSetInt.res b/packages/@rescript/runtime/Belt_MutableSetInt.res
index 447c5bad7fc..01b0feac7f5 100644
--- a/packages/@rescript/runtime/Belt_MutableSetInt.res
+++ b/packages/@rescript/runtime/Belt_MutableSetInt.res
@@ -179,9 +179,7 @@ let make = () => {data: None}
 
 let isEmpty = d => N.isEmpty(d.data)
 let minimum = d => N.minimum(d.data)
-let minUndefined = d => N.minUndefined(d.data)
 let maximum = d => N.maximum(d.data)
-let maxUndefined = d => N.maxUndefined(d.data)
 let forEach = (d, f) => N.forEach(d.data, f)
 let reduce = (d, acc, cb) => N.reduce(d.data, acc, cb)
 let every = (d, p) => N.every(d.data, p)
@@ -199,7 +197,6 @@ let fromArray = xs => {data: I.fromArray(xs)}
 let cmp = (d0, d1) => I.cmp(d0.data, d1.data)
 let eq = (d0, d1) => I.eq(d0.data, d1.data)
 let get = (d, x) => I.get(d.data, x)
-let getUndefined = (d, x) => I.getUndefined(d.data, x)
 let getOrThrow = (d, x) => I.getOrThrow(d.data, x)
 let getExn = getOrThrow
 
diff --git a/packages/@rescript/runtime/Belt_MutableSetInt.resi b/packages/@rescript/runtime/Belt_MutableSetInt.resi
index e6c5c81bcf9..d64bf370448 100644
--- a/packages/@rescript/runtime/Belt_MutableSetInt.resi
+++ b/packages/@rescript/runtime/Belt_MutableSetInt.resi
@@ -100,12 +100,9 @@ let toList: t => list<value>
 let toArray: t => array<value>
 
 let minimum: t => option<value>
-let minUndefined: t => Js.undefined<value>
 let maximum: t => option<value>
-let maxUndefined: t => Js.undefined<value>
 
 let get: (t, value) => option<value>
-let getUndefined: (t, value) => Js.undefined<value>
 let getExn: (t, value) => value
 let getOrThrow: (t, value) => value
 
diff --git a/packages/@rescript/runtime/Belt_MutableSetString.res b/packages/@rescript/runtime/Belt_MutableSetString.res
index 8e9129413d7..27557a4e28f 100644
--- a/packages/@rescript/runtime/Belt_MutableSetString.res
+++ b/packages/@rescript/runtime/Belt_MutableSetString.res
@@ -179,9 +179,7 @@ let make = () => {data: None}
 
 let isEmpty = d => N.isEmpty(d.data)
 let minimum = d => N.minimum(d.data)
-let minUndefined = d => N.minUndefined(d.data)
 let maximum = d => N.maximum(d.data)
-let maxUndefined = d => N.maxUndefined(d.data)
 let forEach = (d, f) => N.forEach(d.data, f)
 let reduce = (d, acc, cb) => N.reduce(d.data, acc, cb)
 let every = (d, p) => N.every(d.data, p)
@@ -199,7 +197,6 @@ let fromArray = xs => {data: I.fromArray(xs)}
 let cmp = (d0, d1) => I.cmp(d0.data, d1.data)
 let eq = (d0, d1) => I.eq(d0.data, d1.data)
 let get = (d, x) => I.get(d.data, x)
-let getUndefined = (d, x) => I.getUndefined(d.data, x)
 let getOrThrow = (d, x) => I.getOrThrow(d.data, x)
 let getExn = getOrThrow
 
diff --git a/packages/@rescript/runtime/Belt_MutableSetString.resi b/packages/@rescript/runtime/Belt_MutableSetString.resi
index 341385e2d43..94381f493ce 100644
--- a/packages/@rescript/runtime/Belt_MutableSetString.resi
+++ b/packages/@rescript/runtime/Belt_MutableSetString.resi
@@ -100,12 +100,9 @@ let toList: t => list<value>
 let toArray: t => array<value>
 
 let minimum: t => option<value>
-let minUndefined: t => Js.undefined<value>
 let maximum: t => option<value>
-let maxUndefined: t => Js.undefined<value>
 
 let get: (t, value) => option<value>
-let getUndefined: (t, value) => Js.undefined<value>
 let getExn: (t, value) => value
 let getOrThrow: (t, value) => value
 
diff --git a/packages/@rescript/runtime/Belt_MutableStack.res b/packages/@rescript/runtime/Belt_MutableStack.res
index a9a3b815a05..7b5db2a48a7 100644
--- a/packages/@rescript/runtime/Belt_MutableStack.res
+++ b/packages/@rescript/runtime/Belt_MutableStack.res
@@ -19,12 +19,6 @@ let copy = (s: t<_>): t<_> => {root: s.root}
 
 let push = (s, x) => s.root = Some({head: x, tail: s.root})
 
-let topUndefined = (s: t<'a>) =>
-  switch s.root {
-  | None => Js.undefined
-  | Some(x) => Js.Undefined.return(x.head)
-  }
-
 let top = s =>
   switch s.root {
   | None => None
@@ -33,20 +27,20 @@ let top = s =>
 
 let isEmpty = s => s.root == None
 
-let popUndefined = s =>
+let pop = s =>
   switch s.root {
-  | None => Js.undefined
+  | None => None
   | Some(x) =>
     s.root = x.tail
-    Js.Undefined.return(x.head)
+    Some(x.head)
   }
 
-let pop = s =>
+let popOrThrow = s =>
   switch s.root {
-  | None => None
+  | None => throw(Not_found)
   | Some(x) =>
     s.root = x.tail
-    Some(x.head)
+    x.head
   }
 
 let rec lengthAux = (x: cell<_>, acc) =>
diff --git a/packages/@rescript/runtime/Belt_MutableStack.resi b/packages/@rescript/runtime/Belt_MutableStack.resi
index 7fbaae07ee4..33ba0017236 100644
--- a/packages/@rescript/runtime/Belt_MutableStack.resi
+++ b/packages/@rescript/runtime/Belt_MutableStack.resi
@@ -27,9 +27,8 @@ let clear: t<'a> => unit
 let copy: t<'a> => t<'a>
 
 let push: (t<'a>, 'a) => unit
-let popUndefined: t<'a> => Js.undefined<'a>
 let pop: t<'a> => option<'a>
-let topUndefined: t<'a> => Js.undefined<'a>
+let popOrThrow: t<'a> => 'a
 let top: t<'a> => option<'a>
 let isEmpty: t<'a> => bool
 let size: t<'a> => int
diff --git a/packages/@rescript/runtime/Belt_Set.res b/packages/@rescript/runtime/Belt_Set.res
index 0ff9f314882..068e57b56f8 100644
--- a/packages/@rescript/runtime/Belt_Set.res
+++ b/packages/@rescript/runtime/Belt_Set.res
@@ -104,14 +104,10 @@ let toList = m => Dict.toList(m.data)
 let toArray = m => Dict.toArray(m.data)
 
 let minimum = m => Dict.minimum(m.data)
-let minUndefined = m => Dict.minUndefined(m.data)
 let maximum = m => Dict.maximum(m.data)
-let maxUndefined = m => Dict.maxUndefined(m.data)
 
 let get = (m, e) => Dict.get(~cmp=m.cmp, m.data, e)
 
-let getUndefined = (m, e) => Dict.getUndefined(~cmp=m.cmp, m.data, e)
-
 let getOrThrow = (m, e) => Dict.getOrThrow(~cmp=m.cmp, m.data, e)
 
 let getExn = getOrThrow
diff --git a/packages/@rescript/runtime/Belt_Set.resi b/packages/@rescript/runtime/Belt_Set.resi
index 352592f92c0..8d71784b8d4 100644
--- a/packages/@rescript/runtime/Belt_Set.resi
+++ b/packages/@rescript/runtime/Belt_Set.resi
@@ -568,26 +568,6 @@ s1->Belt.Set.minimum == Some(1)
 */
 let minimum: t<'value, 'id> => option<'value>
 
-/**
-Returns minimum value of the collection. `undefined` if collection is empty.
-
-## Examples
-
-```rescript
-module IntCmp = Belt.Id.MakeComparable({
-  type t = int
-  let cmp = Pervasives.compare
-})
-
-let s0 = Belt.Set.make(~id=module(IntCmp))
-let s1 = Belt.Set.fromArray([3, 2, 1, 5], ~id=module(IntCmp))
-
-s0->Belt.Set.minUndefined->Js.Undefined.toOption == None
-s1->Belt.Set.minUndefined->Js.Undefined.toOption == Some(1)
-```
-*/
-let minUndefined: t<'value, 'id> => Js.undefined<'value>
-
 /**
 Returns maximum value of the collection. `None` if collection is empty.
 
@@ -608,31 +588,6 @@ s1->Belt.Set.maximum == Some(5)
 */
 let maximum: t<'value, 'id> => option<'value>
 
-/**
-Returns maximum value of the collection. `undefined` if collection is empty.
-
-## Examples
-
-```rescript
-module IntCmp = Belt.Id.MakeComparable({
-  type t = int
-  let cmp = Pervasives.compare
-})
-
-let s0 = Belt.Set.make(~id=module(IntCmp))
-let s1 = Belt.Set.fromArray([3, 2, 1, 5], ~id=module(IntCmp))
-
-s0
-->Belt.Set.maxUndefined
-->Js.Undefined.toOption == None
-
-s1
-->Belt.Set.maxUndefined
-->Js.Undefined.toOption == Some(5)
-```
-*/
-let maxUndefined: t<'value, 'id> => Js.undefined<'value>
-
 /**
 Returns the reference of the value which is equivalent to value using the comparator specifiecd by this collection. Returns `None` if element does not exist.
 
@@ -652,11 +607,6 @@ s0->Belt.Set.get(20) == None
 */
 let get: (t<'value, 'id>, 'value) => option<'value>
 
-/**
-Same as [get](#get) but returns `undefined` when element does not exist.
-*/
-let getUndefined: (t<'value, 'id>, 'value) => Js.undefined<'value>
-
 /**
 Same as [get](#get) but throw when element does not exist.
 */
diff --git a/packages/@rescript/runtime/Belt_SetDict.res b/packages/@rescript/runtime/Belt_SetDict.res
index c3ad5002c5b..a8879d903c0 100644
--- a/packages/@rescript/runtime/Belt_SetDict.res
+++ b/packages/@rescript/runtime/Belt_SetDict.res
@@ -230,12 +230,9 @@ let toList = N.toList
 let toArray = N.toArray
 let minimum = N.minimum
 let maximum = N.maximum
-let maxUndefined = N.maxUndefined
-let minUndefined = N.minUndefined
 let get = N.get
 let getOrThrow = N.getOrThrow
 let getExn = getOrThrow
-let getUndefined = N.getUndefined
 
 let fromSortedArrayUnsafe = N.fromSortedArrayUnsafe
 let subset = N.subset
diff --git a/packages/@rescript/runtime/Belt_SetDict.resi b/packages/@rescript/runtime/Belt_SetDict.resi
index ce83362a7c7..c2a5354a6c7 100644
--- a/packages/@rescript/runtime/Belt_SetDict.resi
+++ b/packages/@rescript/runtime/Belt_SetDict.resi
@@ -499,26 +499,6 @@ s1->Belt.Set.Dict.minimum == Some(1)
 */
 let minimum: t<'value, 'id> => option<'value>
 
-/**
-Returns minimum value of the collection. `undefined` if collection is empty.
-
-## Examples
-
-```rescript
-module IntCmp = Belt.Id.MakeComparable({
-  type t = int
-  let cmp = Pervasives.compare
-})
-
-let s0 = Belt.Set.Dict.empty
-let s1 = Belt.Set.Dict.fromArray([3, 2, 1, 5], ~cmp=IntCmp.cmp)
-
-s0->Belt.Set.Dict.minUndefined == Js.undefined
-s1->Belt.Set.Dict.minUndefined == Js.Undefined.return(1)
-```
-*/
-let minUndefined: t<'value, 'id> => Js.undefined<'value>
-
 /**
 Returns maximum value of the collection. `None` if collection is empty.
 
@@ -539,26 +519,6 @@ s1->Belt.Set.Dict.maximum == Some(5)
 */
 let maximum: t<'value, 'id> => option<'value>
 
-/**
-Returns maximum value of the collection. `undefined` if collection is empty.
-
-## Examples
-
-```rescript
-module IntCmp = Belt.Id.MakeComparable({
-  type t = int
-  let cmp = Pervasives.compare
-})
-
-let s0 = Belt.Set.Dict.empty
-let s1 = Belt.Set.Dict.fromArray([3, 2, 1, 5], ~cmp=IntCmp.cmp)
-
-s0->Belt.Set.Dict.maxUndefined == Js.undefined
-s1->Belt.Set.Dict.maxUndefined == Js.Undefined.return(5)
-```
-*/
-let maxUndefined: t<'value, 'id> => Js.undefined<'value>
-
 /**
 Returns the reference of the value which is equivalent to value using the comparator
 specifiecd by this collection. Returns `None` if element does not exist.
@@ -579,11 +539,6 @@ s0->Belt.Set.Dict.get(20, ~cmp=IntCmp.cmp) == None
 */
 let get: (t<'value, 'id>, 'value, ~cmp: cmp<'value, 'id>) => option<'value>
 
-/**
-Same as [get](#get) but returns `undefined` when element does not exist.
-*/
-let getUndefined: (t<'value, 'id>, 'value, ~cmp: cmp<'value, 'id>) => Js.undefined<'value>
-
 /**
 Same as [get](#get) but throw when element does not exist.
 */
diff --git a/packages/@rescript/runtime/Belt_SetInt.res b/packages/@rescript/runtime/Belt_SetInt.res
index 238516c821a..c6c649c159d 100644
--- a/packages/@rescript/runtime/Belt_SetInt.res
+++ b/packages/@rescript/runtime/Belt_SetInt.res
@@ -9,9 +9,7 @@ type t = I.t
 let empty = None
 let isEmpty = N.isEmpty
 let minimum = N.minimum
-let minUndefined = N.minUndefined
 let maximum = N.maximum
-let maxUndefined = N.maxUndefined
 
 let forEach = N.forEach
 let reduce = N.reduce
@@ -108,7 +106,6 @@ let fromArray = I.fromArray
 let cmp = I.cmp
 let eq = I.eq
 let get = I.get
-let getUndefined = I.getUndefined
 let getOrThrow = I.getOrThrow
 let getExn = getOrThrow
 let subset = I.subset
diff --git a/packages/@rescript/runtime/Belt_SetInt.resi b/packages/@rescript/runtime/Belt_SetInt.resi
index 29d4fb5f839..590576256de 100644
--- a/packages/@rescript/runtime/Belt_SetInt.resi
+++ b/packages/@rescript/runtime/Belt_SetInt.resi
@@ -124,16 +124,10 @@ let toArray: t => array<value>
 
 let minimum: t => option<value>
 
-let minUndefined: t => Js.undefined<value>
-
 let maximum: t => option<value>
 
-let maxUndefined: t => Js.undefined<value>
-
 let get: (t, value) => option<value>
 
-let getUndefined: (t, value) => Js.undefined<value>
-
 let getExn: (t, value) => value
 
 let getOrThrow: (t, value) => value
diff --git a/packages/@rescript/runtime/Belt_SetString.res b/packages/@rescript/runtime/Belt_SetString.res
index 7644cf724a5..c04c1fa0401 100644
--- a/packages/@rescript/runtime/Belt_SetString.res
+++ b/packages/@rescript/runtime/Belt_SetString.res
@@ -9,9 +9,7 @@ type t = I.t
 let empty = None
 let isEmpty = N.isEmpty
 let minimum = N.minimum
-let minUndefined = N.minUndefined
 let maximum = N.maximum
-let maxUndefined = N.maxUndefined
 
 let forEach = N.forEach
 let reduce = N.reduce
@@ -108,7 +106,6 @@ let fromArray = I.fromArray
 let cmp = I.cmp
 let eq = I.eq
 let get = I.get
-let getUndefined = I.getUndefined
 let getOrThrow = I.getOrThrow
 let getExn = getOrThrow
 let subset = I.subset
diff --git a/packages/@rescript/runtime/Belt_SetString.resi b/packages/@rescript/runtime/Belt_SetString.resi
index f6ab842f0c9..ec0f8cb375f 100644
--- a/packages/@rescript/runtime/Belt_SetString.resi
+++ b/packages/@rescript/runtime/Belt_SetString.resi
@@ -124,16 +124,10 @@ let toArray: t => array<value>
 
 let minimum: t => option<value>
 
-let minUndefined: t => Js.undefined<value>
-
 let maximum: t => option<value>
 
-let maxUndefined: t => Js.undefined<value>
-
 let get: (t, value) => option<value>
 
-let getUndefined: (t, value) => Js.undefined<value>
-
 let getExn: (t, value) => value
 
 let getOrThrow: (t, value) => value
diff --git a/packages/@rescript/runtime/Belt_internalAVLset.res b/packages/@rescript/runtime/Belt_internalAVLset.res
index 0830ed6addc..1d11d4cda43 100644
--- a/packages/@rescript/runtime/Belt_internalAVLset.res
+++ b/packages/@rescript/runtime/Belt_internalAVLset.res
@@ -116,12 +116,6 @@ let minimum = n =>
   | Some(n) => Some(min0Aux(n))
   }
 
-let minUndefined = n =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) => Js.Undefined.return(min0Aux(n))
-  }
-
 let rec max0Aux = n =>
   switch n.right {
   | None => n.value
@@ -134,12 +128,6 @@ let maximum = n =>
   | Some(n) => Some(max0Aux(n))
   }
 
-let maxUndefined = n =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) => Js.Undefined.return(max0Aux(n))
-  }
-
 let rec removeMinAuxWithRef = (n, v) =>
   switch n.left {
   | None =>
@@ -549,27 +537,6 @@ let rec get = (n: t<_>, x, ~cmp) =>
     }
   }
 
-let rec getUndefined = (n: t<_>, x, ~cmp) =>
-  switch n {
-  | None => Js.Undefined.empty
-  | Some(t) /* Node(l, v, r, _) */ =>
-    let v = t.value
-    let c = Belt_Id.getCmpInternal(cmp)(x, v)
-    if c == 0 {
-      Js.Undefined.return(v)
-    } else {
-      getUndefined(
-        ~cmp,
-        if c < 0 {
-          t.left
-        } else {
-          t.right
-        },
-        x,
-      )
-    }
-  }
-
 let rec getOrThrow = (n: t<_>, x, ~cmp) =>
   switch n {
   | None => throw(Not_found)
diff --git a/packages/@rescript/runtime/Belt_internalAVLset.resi b/packages/@rescript/runtime/Belt_internalAVLset.resi
index 5606c32da7a..3703c0f31ec 100644
--- a/packages/@rescript/runtime/Belt_internalAVLset.resi
+++ b/packages/@rescript/runtime/Belt_internalAVLset.resi
@@ -25,9 +25,7 @@ let bal: (t<'a>, 'a, t<'a>) => t<'a>
 let singleton: 'a => t<'a>
 
 let minimum: t<'a> => option<'a>
-let minUndefined: t<'a> => Js.undefined<'a>
 let maximum: t<'a> => option<'a>
-let maxUndefined: t<'a> => Js.undefined<'a>
 
 let removeMinAuxWithRef: (node<'a>, ref<'a>) => t<'a>
 /* `removeMinAuxWithRef n cell` return a new node with
@@ -76,7 +74,6 @@ let cmp: (t<'a>, t<'a>, ~cmp: cmp<'a, 'b>) => int
 let eq: (t<'a>, t<'a>, ~cmp: cmp<'a, 'b>) => bool
 let subset: (t<'a>, t<'a>, ~cmp: cmp<'a, 'b>) => bool
 let get: (t<'a>, 'a, ~cmp: cmp<'a, 'b>) => option<'a>
-let getUndefined: (t<'a>, 'a, ~cmp: cmp<'a, 'b>) => Js.undefined<'a>
 let getOrThrow: (t<'a>, 'a, ~cmp: cmp<'a, 'b>) => 'a
 
 let fromArray: (array<'a>, ~cmp: cmp<'a, 'b>) => t<'a>
diff --git a/packages/@rescript/runtime/Belt_internalAVLtree.res b/packages/@rescript/runtime/Belt_internalAVLtree.res
index 5bd2b63ef8d..80f3ded37c1 100644
--- a/packages/@rescript/runtime/Belt_internalAVLtree.res
+++ b/packages/@rescript/runtime/Belt_internalAVLtree.res
@@ -134,12 +134,6 @@ let minKey = n =>
   | Some(n) => Some(minKey0Aux(n))
   }
 
-let minKeyUndefined = n =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) => Js.Undefined.return(minKey0Aux(n))
-  }
-
 let rec maxKey0Aux = n =>
   switch n.right {
   | None => n.key
@@ -152,12 +146,6 @@ let maxKey = n =>
   | Some(n) => Some(maxKey0Aux(n))
   }
 
-let maxKeyUndefined = n =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) => Js.Undefined.return(maxKey0Aux(n))
-  }
-
 let rec minKV0Aux = n =>
   switch n.left {
   | None => (n.key, n.value)
@@ -170,12 +158,6 @@ let minimum = n =>
   | Some(n) => Some(minKV0Aux(n))
   }
 
-let minUndefined = n =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) => Js.Undefined.return(minKV0Aux(n))
-  }
-
 let rec maxKV0Aux = n =>
   switch n.right {
   | None => (n.key, n.value)
@@ -188,12 +170,6 @@ let maximum = n =>
   | Some(n) => Some(maxKV0Aux(n))
   }
 
-let maxUndefined = n =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) => Js.Undefined.return(maxKV0Aux(n))
-  }
-
 /* TODO: use kv ref */
 let rec removeMinAuxWithRef = (n, kr, vr) =>
   switch n.left {
@@ -683,27 +659,6 @@ let rec get = (n, x, ~cmp) =>
     }
   }
 
-let rec getUndefined = (n, x, ~cmp) =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) =>
-    let v = n.key
-    let c = Belt_Id.getCmpInternal(cmp)(x, v)
-    if c == 0 {
-      Js.Undefined.return(n.value)
-    } else {
-      getUndefined(
-        ~cmp,
-        if c < 0 {
-          n.left
-        } else {
-          n.right
-        },
-        x,
-      )
-    }
-  }
-
 let rec getOrThrow = (n, x, ~cmp) =>
   switch n {
   | None => throw(Not_found)
diff --git a/packages/@rescript/runtime/Belt_internalAVLtree.resi b/packages/@rescript/runtime/Belt_internalAVLtree.resi
index 614ff1fd7d2..c204c8db792 100644
--- a/packages/@rescript/runtime/Belt_internalAVLtree.resi
+++ b/packages/@rescript/runtime/Belt_internalAVLtree.resi
@@ -25,16 +25,12 @@ let singleton: ('a, 'b) => t<'a, 'b>
 let updateValue: (node<'k, 'v>, 'v) => node<'k, 'v>
 
 let minKey: t<'a, 'b> => option<'a>
-let minKeyUndefined: t<'a, 'b> => Js.undefined<'a>
 
 let maxKey: t<'a, 'b> => option<'a>
-let maxKeyUndefined: t<'a, 'b> => Js.undefined<'a>
 
 let minimum: t<'a, 'b> => option<('a, 'b)>
-let minUndefined: t<'a, 'b> => Js.undefined<('a, 'b)>
 
 let maximum: t<'a, 'b> => option<('a, 'b)>
-let maxUndefined: t<'a, 'b> => Js.undefined<('a, 'b)>
 
 let removeMinAuxWithRef: (node<'a, 'b>, ref<'a>, ref<'b>) => t<'a, 'b>
 
@@ -93,8 +89,6 @@ let eq: (t<'a, 'b>, t<'a, 'c>, ~kcmp: cmp<'a, _>, ~veq: ('b, 'c) => bool) => boo
 
 let get: (t<'a, 'b>, 'a, ~cmp: cmp<'a, _>) => option<'b>
 
-let getUndefined: (t<'a, 'b>, 'a, ~cmp: cmp<'a, _>) => Js.undefined<'b>
-
 let getWithDefault: (t<'a, 'b>, 'a, 'b, ~cmp: cmp<'a, _>) => 'b
 let getOrThrow: (t<'a, 'b>, 'a, ~cmp: cmp<'a, _>) => 'b
 
diff --git a/packages/@rescript/runtime/Belt_internalMapInt.res b/packages/@rescript/runtime/Belt_internalMapInt.res
index 8a750ca393c..ae1ce3a6314 100644
--- a/packages/@rescript/runtime/Belt_internalMapInt.res
+++ b/packages/@rescript/runtime/Belt_internalMapInt.res
@@ -44,25 +44,6 @@ let rec get = (n, x: key) =>
     }
   }
 
-let rec getUndefined = (n, x: key) =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) =>
-    let v = n.N.key
-    if x == v {
-      Js.Undefined.return(n.N.value)
-    } else {
-      getUndefined(
-        if x < v {
-          n.N.left
-        } else {
-          n.N.right
-        },
-        x,
-      )
-    }
-  }
-
 let rec getOrThrow = (n, x: key) =>
   switch n {
   | None => throw(Not_found)
diff --git a/packages/@rescript/runtime/Belt_internalMapString.res b/packages/@rescript/runtime/Belt_internalMapString.res
index 000acdb1473..9426d076f4f 100644
--- a/packages/@rescript/runtime/Belt_internalMapString.res
+++ b/packages/@rescript/runtime/Belt_internalMapString.res
@@ -44,25 +44,6 @@ let rec get = (n, x: key) =>
     }
   }
 
-let rec getUndefined = (n, x: key) =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) =>
-    let v = n.N.key
-    if x == v {
-      Js.Undefined.return(n.N.value)
-    } else {
-      getUndefined(
-        if x < v {
-          n.N.left
-        } else {
-          n.N.right
-        },
-        x,
-      )
-    }
-  }
-
 let rec getOrThrow = (n, x: key) =>
   switch n {
   | None => throw(Not_found)
diff --git a/packages/@rescript/runtime/Belt_internalSetInt.res b/packages/@rescript/runtime/Belt_internalSetInt.res
index c756d09d5aa..55029c22473 100644
--- a/packages/@rescript/runtime/Belt_internalSetInt.res
+++ b/packages/@rescript/runtime/Belt_internalSetInt.res
@@ -85,25 +85,6 @@ let rec get = (n: t, x: value) =>
     }
   }
 
-let rec getUndefined = (n: t, x: value) =>
-  switch n {
-  | None => Js.undefined
-  | Some(t) =>
-    let v = t.value
-    if x == v {
-      Js.Undefined.return(v)
-    } else {
-      getUndefined(
-        if x < v {
-          t.left
-        } else {
-          t.right
-        },
-        x,
-      )
-    }
-  }
-
 let rec getOrThrow = (n: t, x: value) =>
   switch n {
   | None => throw(Not_found)
diff --git a/packages/@rescript/runtime/Belt_internalSetString.res b/packages/@rescript/runtime/Belt_internalSetString.res
index bff62d16894..910a1d0aaf9 100644
--- a/packages/@rescript/runtime/Belt_internalSetString.res
+++ b/packages/@rescript/runtime/Belt_internalSetString.res
@@ -85,25 +85,6 @@ let rec get = (n: t, x: value) =>
     }
   }
 
-let rec getUndefined = (n: t, x: value) =>
-  switch n {
-  | None => Js.undefined
-  | Some(t) =>
-    let v = t.value
-    if x == v {
-      Js.Undefined.return(v)
-    } else {
-      getUndefined(
-        if x < v {
-          t.left
-        } else {
-          t.right
-        },
-        x,
-      )
-    }
-  }
-
 let rec getOrThrow = (n: t, x: value) =>
   switch n {
   | None => throw(Not_found)
diff --git a/packages/@rescript/runtime/cppo/belt_Set.res.cppo b/packages/@rescript/runtime/cppo/belt_Set.res.cppo
index 9b649f81800..ed78783e808 100644
--- a/packages/@rescript/runtime/cppo/belt_Set.res.cppo
+++ b/packages/@rescript/runtime/cppo/belt_Set.res.cppo
@@ -15,9 +15,7 @@ type t = I.t
 let empty = None
 let isEmpty = N.isEmpty
 let minimum = N.minimum
-let minUndefined = N.minUndefined
 let maximum = N.maximum
-let maxUndefined = N.maxUndefined
 
 let forEach = N.forEach
 let reduce = N.reduce
@@ -114,8 +112,8 @@ let fromArray = I.fromArray
 let cmp = I.cmp
 let eq = I.eq
 let get = I.get
-let getUndefined = I.getUndefined
-let getExn = I.getExn
+let getOrThrow = I.getOrThrow
+let getExn = getOrThrow
 let subset = I.subset
 let has = I.has
 
diff --git a/packages/@rescript/runtime/cppo/belt_Set.resi.cppo b/packages/@rescript/runtime/cppo/belt_Set.resi.cppo
index 7765a32daf5..aa18d2f94c1 100644
--- a/packages/@rescript/runtime/cppo/belt_Set.resi.cppo
+++ b/packages/@rescript/runtime/cppo/belt_Set.resi.cppo
@@ -1,26 +1,8 @@
-/* Copyright (C) 2017 Authors of ReScript
+/* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * Copyright (C) 2017- Hongbo Zhang, Authors of ReScript
  *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ * SPDX-License-Identifier: MIT
+ */
 
 /***
 This module is [`Belt.Set`]() specialized with value type to be a primitive type.
@@ -149,18 +131,14 @@ let toArray: t => array<value>
 
 let minimum: t => option<value>
 
-let minUndefined: t => Js.undefined<value>
-
 let maximum: t => option<value>
 
-let maxUndefined: t => Js.undefined<value>
-
 let get: (t, value) => option<value>
 
-let getUndefined: (t, value) => Js.undefined<value>
-
 let getExn: (t, value) => value
 
+let getOrThrow: (t, value) => value
+
 /**
 `split(x, s)` returns a triple `(l, present, r)`, where `l` is the set of
 elements of `s` that are strictly less than `x`;`r` is the set of elements of
diff --git a/packages/@rescript/runtime/cppo/hashmap.res.cppo b/packages/@rescript/runtime/cppo/hashmap.res.cppo
index 4e07f9c5709..931e8fddbac 100644
--- a/packages/@rescript/runtime/cppo/hashmap.res.cppo
+++ b/packages/@rescript/runtime/cppo/hashmap.res.cppo
@@ -1,15 +1,8 @@
-/* ********************************************************************* */
-/*  */
-/* OCaml */
-/*  */
-/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
-/*  */
-/* Copyright 1996 Institut National de Recherche en Informatique et */
-/* en Automatique.  All rights reserved.  This file is distributed */
-/* under the terms of the GNU Library General Public License, with */
-/* the special exception on linking described in file ../LICENSE. */
-/*  */
-/* ********************************************************************* */
+/* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * Copyright (C) 2017- Hongbo Zhang, Authors of ReScript
+ *
+ * SPDX-License-Identifier: MIT
+ */
 
 /* Adapted by Hongbo Zhang, Authors of ReScript 2017 */
 
diff --git a/packages/@rescript/runtime/cppo/hashset.resi.cppo b/packages/@rescript/runtime/cppo/hashset.resi.cppo
index 6b2b8423820..cb6db42827e 100644
--- a/packages/@rescript/runtime/cppo/hashset.resi.cppo
+++ b/packages/@rescript/runtime/cppo/hashset.resi.cppo
@@ -1,26 +1,8 @@
-/* Copyright (C) 2017 Authors of ReScript
+/* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * Copyright (C) 2017- Hongbo Zhang, Authors of ReScript
  *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ * SPDX-License-Identifier: MIT
+ */
 
 /***
 This module is [`Belt.HashSet`]() specialized with key type to be a primitive type.
diff --git a/packages/@rescript/runtime/cppo/internal_map.res.cppo b/packages/@rescript/runtime/cppo/internal_map.res.cppo
index 6e44c22850f..c0ed3e0c6e5 100644
--- a/packages/@rescript/runtime/cppo/internal_map.res.cppo
+++ b/packages/@rescript/runtime/cppo/internal_map.res.cppo
@@ -50,26 +50,7 @@ let rec get = (n, x: key) =>
     }
   }
 
-let rec getUndefined = (n, x: key) =>
-  switch n {
-  | None => Js.undefined
-  | Some(n) =>
-    let v = n.N.key
-    if x == v {
-      Js.Undefined.return(n.N.value)
-    } else {
-      getUndefined(
-        if x < v {
-          n.N.left
-        } else {
-          n.N.right
-        },
-        x,
-      )
-    }
-  }
-
-let rec getExn = (n, x: key) =>
+let rec getOrThrow = (n, x: key) =>
   switch n {
   | None => throw(Not_found)
   | Some(n) =>
@@ -77,7 +58,7 @@ let rec getExn = (n, x: key) =>
     if x == v {
       n.N.value
     } else {
-      getExn(
+      getOrThrow(
         if x < v {
           n.N.left
         } else {
diff --git a/packages/@rescript/runtime/cppo/internal_set.res.cppo b/packages/@rescript/runtime/cppo/internal_set.res.cppo
index e517b7da658..3a5738af434 100644
--- a/packages/@rescript/runtime/cppo/internal_set.res.cppo
+++ b/packages/@rescript/runtime/cppo/internal_set.res.cppo
@@ -92,26 +92,7 @@ let rec get = (n: t, x: value) =>
     }
   }
 
-let rec getUndefined = (n: t, x: value) =>
-  switch n {
-  | None => Js.undefined
-  | Some(t) =>
-    let v = t.value
-    if x == v {
-      Js.Undefined.return(v)
-    } else {
-      getUndefined(
-        if x < v {
-          t.left
-        } else {
-          t.right
-        },
-        x,
-      )
-    }
-  }
-
-let rec getExn = (n: t, x: value) =>
+let rec getOrThrow = (n: t, x: value) =>
   switch n {
   | None => throw(Not_found)
   | Some(t) =>
@@ -119,7 +100,7 @@ let rec getExn = (n: t, x: value) =>
     if x == v {
       v
     } else {
-      getExn(
+      getOrThrow(
         if x < v {
           t.left
         } else {
diff --git a/packages/@rescript/runtime/cppo/map.res.cppo b/packages/@rescript/runtime/cppo/map.res.cppo
index 6dbae0188b3..6f0d95d8771 100644
--- a/packages/@rescript/runtime/cppo/map.res.cppo
+++ b/packages/@rescript/runtime/cppo/map.res.cppo
@@ -18,13 +18,9 @@ let isEmpty = N.isEmpty
 /* let singleton = N.singleton */
 
 let minKey = N.minKey
-let minKeyUndefined = N.minKeyUndefined
 let maxKey = N.maxKey
-let maxKeyUndefined = N.maxKeyUndefined
 let minimum = N.minimum
-let minUndefined = N.minUndefined
 let maximum = N.maximum
-let maxUndefined = N.maxUndefined
 let findFirstBy = N.findFirstBy
 let forEach = N.forEach
 let map = N.map
@@ -176,9 +172,9 @@ let has = I.has
 let cmp = I.cmp
 let eq = I.eq
 let get = I.get
-let getUndefined = I.getUndefined
 let getWithDefault = I.getWithDefault
-let getExn = I.getExn
+let getOrThrow = I.getOrThrow
+let getExn = getOrThrow
 let split = I.split
 let merge = I.merge
 let fromArray = I.fromArray
diff --git a/packages/@rescript/runtime/cppo/map.resi.cppo b/packages/@rescript/runtime/cppo/map.resi.cppo
index f339f2b7243..2a0d3a80d05 100644
--- a/packages/@rescript/runtime/cppo/map.resi.cppo
+++ b/packages/@rescript/runtime/cppo/map.resi.cppo
@@ -42,15 +42,11 @@ to match predicate `p`.
 #ifdef TYPE_STRING
 let mapString = Belt.Map.String.fromArray([("1", "one"), ("2", "two"), ("3", "three")])
 
-mapString->
-Belt.Map.String.findFirstBy((k, v) => k == "1" && v == "one")
-->assertEqual(Some("1", "one"))
+mapString->Belt.Map.String.findFirstBy((k, v) => k == "1" && v == "one") == Some("1", "one")
 #elif defined TYPE_INT
 let mapInt = Belt.Map.Int.fromArray([(1, "one"), (2, "two"), (3, "three")])
 
-mapInt->
-Belt.Map.Int.findFirstBy((k, v) => k == 1 && v == "one")
-->assertEqual(Some(1, "one"))
+mapInt->Belt.Map.Int.findFirstBy((k, v) => k == 1 && v == "one") == Some(1, "one")
 #else
 [%error "unknown type"]
 #endif
@@ -110,28 +106,20 @@ let valuesToArray: t<'v> => array<'v>
 
 let minKey: t<_> => option<key>
 
-let minKeyUndefined: t<_> => Js.undefined<key>
-
 let maxKey: t<_> => option<key>
 
-let maxKeyUndefined: t<_> => Js.undefined<key>
-
 let minimum: t<'v> => option<(key, 'v)>
 
-let minUndefined: t<'v> => Js.undefined<(key, 'v)>
-
 let maximum: t<'v> => option<(key, 'v)>
 
-let maxUndefined: t<'v> => Js.undefined<(key, 'v)>
-
 let get: (t<'v>, key) => option<'v>
 
-let getUndefined: (t<'v>, key) => Js.undefined<'v>
-
 let getWithDefault: (t<'v>, key, 'v) => 'v
 
 let getExn: (t<'v>, key) => 'v
 
+let getOrThrow: (t<'v>, key) => 'v
+
 /**
 **throw** when invariant is not held
 */
diff --git a/packages/@rescript/runtime/cppo/mapm.res.cppo b/packages/@rescript/runtime/cppo/mapm.res.cppo
index 4820a22f851..47229cbf0d9 100644
--- a/packages/@rescript/runtime/cppo/mapm.res.cppo
+++ b/packages/@rescript/runtime/cppo/mapm.res.cppo
@@ -18,14 +18,10 @@ let isEmpty = m => N.isEmpty(m.data)
 let clear = m => m.data = None
 /* let singleton k v = t ~data:(N.singleton k v) */
 
-let minKeyUndefined = m => N.minKeyUndefined(m.data)
 let minKey = m => N.minKey(m.data)
-let maxKeyUndefined = m => N.maxKeyUndefined(m.data)
 let maxKey = m => N.maxKey(m.data)
 let minimum = m => N.minimum(m.data)
-let minUndefined = m => N.minUndefined(m.data)
 let maximum = m => N.maximum(m.data)
-let maxUndefined = m => N.maxUndefined(m.data)
 
 let set = (m: t<_>, k, v) => {
   let old_data = m.data
@@ -170,9 +166,9 @@ let cmp = (d0, d1, f) => I.cmp(d0.data, d1.data, f)
 let eq = (d0, d1, f) => I.eq(d0.data, d1.data, f)
 
 let get = (d, x) => I.get(d.data, x)
-let getUndefined = (d, x) => I.getUndefined(d.data, x)
 let getWithDefault = (d, x, def) => I.getWithDefault(d.data, x, def)
-let getExn = (d, x) => I.getExn(d.data, x)
+let getOrThrow = (d, x) => I.getOrThrow(d.data, x)
+let getExn = getOrThrow
 
 let cmpU = cmp
 let eqU = eq
diff --git a/packages/@rescript/runtime/cppo/mapm.resi.cppo b/packages/@rescript/runtime/cppo/mapm.resi.cppo
index 7046a3ddfba..83f296c2bc4 100644
--- a/packages/@rescript/runtime/cppo/mapm.resi.cppo
+++ b/packages/@rescript/runtime/cppo/mapm.resi.cppo
@@ -1,26 +1,8 @@
-/* Copyright (C) 2017 Authors of ReScript
+/* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * Copyright (C) 2017- Hongbo Zhang, Authors of ReScript
  *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ * SPDX-License-Identifier: MIT
+ */
 
 #ifdef TYPE_STRING
 type key = string
@@ -101,20 +83,20 @@ let fromArray: array<(key, 'a)> => t<'a>
 let keysToArray: t<'a> => array<key>
 let valuesToArray: t<'a> => array<'a>
 let minKey: t<_> => option<key>
-let minKeyUndefined: t<_> => Js.undefined<key>
 let maxKey: t<_> => option<key>
-let maxKeyUndefined: t<_> => Js.undefined<key>
 let minimum: t<'a> => option<(key, 'a)>
-let minUndefined: t<'a> => Js.undefined<(key, 'a)>
 let maximum: t<'a> => option<(key, 'a)>
-let maxUndefined: t<'a> => Js.undefined<(key, 'a)>
 let get: (t<'a>, key) => option<'a>
-let getUndefined: (t<'a>, key) => Js.undefined<'a>
 let getWithDefault: (t<'a>, key, 'a) => 'a
 let getExn: (t<'a>, key) => 'a
+let getOrThrow: (t<'a>, key) => 'a
 
 /**
+#ifdef TYPE_STRING
   **throw** when invariant is not held
+#else
+  **Throw** when invariant is not held
+#endif
 */
 let checkInvariantInternal: t<_> => unit
 
diff --git a/packages/@rescript/runtime/cppo/setm.res.cppo b/packages/@rescript/runtime/cppo/setm.res.cppo
index f98067938e1..6c8070f0bb6 100644
--- a/packages/@rescript/runtime/cppo/setm.res.cppo
+++ b/packages/@rescript/runtime/cppo/setm.res.cppo
@@ -1,26 +1,8 @@
-/* Copyright (C) 2017 Hongbo Zhang, Authors of ReScript
+/* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * Copyright (C) 2017- Hongbo Zhang, Authors of ReScript
  *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ * SPDX-License-Identifier: MIT
+ */
 
 /*** This module is [`Belt.MutableSet`]() specialized with key type to be a primitive type.
     It is more efficient in general, the  API is the same with [`Belt_MutableSet`]() except its key type is fixed,
@@ -204,9 +186,7 @@ let make = () => {data: None}
 
 let isEmpty = d => N.isEmpty(d.data)
 let minimum = d => N.minimum(d.data)
-let minUndefined = d => N.minUndefined(d.data)
 let maximum = d => N.maximum(d.data)
-let maxUndefined = d => N.maxUndefined(d.data)
 let forEach = (d, f) => N.forEach(d.data, f)
 let reduce = (d, acc, cb) => N.reduce(d.data, acc, cb)
 let every = (d, p) => N.every(d.data, p)
@@ -224,8 +204,8 @@ let fromArray = xs => {data: I.fromArray(xs)}
 let cmp = (d0, d1) => I.cmp(d0.data, d1.data)
 let eq = (d0, d1) => I.eq(d0.data, d1.data)
 let get = (d, x) => I.get(d.data, x)
-let getUndefined = (d, x) => I.getUndefined(d.data, x)
-let getExn = (d, x) => I.getExn(d.data, x)
+let getOrThrow = (d, x) => I.getOrThrow(d.data, x)
+let getExn = getOrThrow
 
 let split = (d, key) => {
   let arr = N.toArray(d.data)
diff --git a/packages/@rescript/runtime/cppo/setm.resi.cppo b/packages/@rescript/runtime/cppo/setm.resi.cppo
index 8e9611b8802..d2eb67f0969 100644
--- a/packages/@rescript/runtime/cppo/setm.resi.cppo
+++ b/packages/@rescript/runtime/cppo/setm.resi.cppo
@@ -1,26 +1,8 @@
-/* Copyright (C) 2017 Authors of ReScript
+/* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * Copyright (C) 2017- Hongbo Zhang, Authors of ReScript
  *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ * SPDX-License-Identifier: MIT
+ */
 
 /***
 This module is [`Belt.MutableSet`]() specialized with key type to be a primitive type.
@@ -125,13 +107,11 @@ let toList: t => list<value>
 let toArray: t => array<value>
 
 let minimum: t => option<value>
-let minUndefined: t => Js.undefined<value>
 let maximum: t => option<value>
-let maxUndefined: t => Js.undefined<value>
 
 let get: (t, value) => option<value>
-let getUndefined: (t, value) => Js.undefined<value>
 let getExn: (t, value) => value
+let getOrThrow: (t, value) => value
 
 /**
 `split(s, key)` return a fresh copy of each
diff --git a/packages/@rescript/runtime/cppo/sort.resi.cppo b/packages/@rescript/runtime/cppo/sort.resi.cppo
index 8570da496fd..ad2015a4ee7 100644
--- a/packages/@rescript/runtime/cppo/sort.resi.cppo
+++ b/packages/@rescript/runtime/cppo/sort.resi.cppo
@@ -1,26 +1,8 @@
-/* Copyright (C) 2017 Authors of ReScript
+/* Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ * Copyright (C) 2017- Hongbo Zhang, Authors of ReScript
  *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * In addition to the permissions granted to you by the LGPL, you may combine
- * or link a "work that uses the Library" with a publicly distributed version
- * of this file to produce a combined library or application, then distribute
- * that combined work under the terms of your choosing, with no requirement
- * to comply with the obligations normally placed on you by section 4 of the
- * LGPL version 3 (or the corresponding section of a later version of the LGPL
- * should you choose to use a later version).
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ * SPDX-License-Identifier: MIT
+ */
 
 /***
 This is a specialized module for [`Belt_SortArray`](), the docs in that module also
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Array.mjs b/packages/@rescript/runtime/lib/es6/Belt_Array.mjs
index 8b7ff062d66..f693ae6d07b 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_Array.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_Array.mjs
@@ -15,7 +15,7 @@ function getOrThrow(arr, i) {
       RE_EXN_ID: "Assert_failure",
       _1: [
         "Belt_Array.res",
-        29,
+        27,
         2
       ],
       Error: new Error()
@@ -39,7 +39,7 @@ function setOrThrow(arr, i, v) {
       RE_EXN_ID: "Assert_failure",
       _1: [
         "Belt_Array.res",
-        44,
+        42,
         2
       ],
       Error: new Error()
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Map.mjs b/packages/@rescript/runtime/lib/es6/Belt_Map.mjs
index 4b499632dd4..037146cdf67 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_Map.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_Map.mjs
@@ -175,42 +175,22 @@ function minKey(m) {
   return Belt_MapDict.minKey(m.data);
 }
 
-function minKeyUndefined(m) {
-  return Belt_MapDict.minKeyUndefined(m.data);
-}
-
 function maxKey(m) {
   return Belt_MapDict.maxKey(m.data);
 }
 
-function maxKeyUndefined(m) {
-  return Belt_MapDict.maxKeyUndefined(m.data);
-}
-
 function minimum(m) {
   return Belt_MapDict.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_MapDict.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_MapDict.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_MapDict.maxUndefined(m.data);
-}
-
 function get(map, x) {
   return Belt_MapDict.get(map.data, x, map.cmp);
 }
 
-function getUndefined(map, x) {
-  return Belt_MapDict.getUndefined(map.data, x, map.cmp);
-}
-
 function getWithDefault(map, x, def) {
   return Belt_MapDict.getWithDefault(map.data, x, def, map.cmp);
 }
@@ -315,15 +295,10 @@ export {
   keysToArray,
   valuesToArray,
   minKey,
-  minKeyUndefined,
   maxKey,
-  maxKeyUndefined,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getWithDefault,
   getExn,
   getOrThrow,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MapDict.mjs b/packages/@rescript/runtime/lib/es6/Belt_MapDict.mjs
index 6458d3fe30c..cd6869b361e 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MapDict.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MapDict.mjs
@@ -304,24 +304,14 @@ let valuesToArray = Belt_internalAVLtree.valuesToArray;
 
 let minKey = Belt_internalAVLtree.minKey;
 
-let minKeyUndefined = Belt_internalAVLtree.minKeyUndefined;
-
 let maxKey = Belt_internalAVLtree.maxKey;
 
-let maxKeyUndefined = Belt_internalAVLtree.maxKeyUndefined;
-
 let minimum = Belt_internalAVLtree.minimum;
 
-let minUndefined = Belt_internalAVLtree.minUndefined;
-
 let maximum = Belt_internalAVLtree.maximum;
 
-let maxUndefined = Belt_internalAVLtree.maxUndefined;
-
 let get = Belt_internalAVLtree.get;
 
-let getUndefined = Belt_internalAVLtree.getUndefined;
-
 let getWithDefault = Belt_internalAVLtree.getWithDefault;
 
 let getExn = Belt_internalAVLtree.getOrThrow;
@@ -375,15 +365,10 @@ export {
   keysToArray,
   valuesToArray,
   minKey,
-  minKeyUndefined,
   maxKey,
-  maxKeyUndefined,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getWithDefault,
   getExn,
   getOrThrow,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MapInt.mjs b/packages/@rescript/runtime/lib/es6/Belt_MapInt.mjs
index 9e7fdb69017..15535ae39c4 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MapInt.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MapInt.mjs
@@ -196,24 +196,14 @@ let valuesToArray = Belt_internalAVLtree.valuesToArray;
 
 let minKey = Belt_internalAVLtree.minKey;
 
-let minKeyUndefined = Belt_internalAVLtree.minKeyUndefined;
-
 let maxKey = Belt_internalAVLtree.maxKey;
 
-let maxKeyUndefined = Belt_internalAVLtree.maxKeyUndefined;
-
 let minimum = Belt_internalAVLtree.minimum;
 
-let minUndefined = Belt_internalAVLtree.minUndefined;
-
 let maximum = Belt_internalAVLtree.maximum;
 
-let maxUndefined = Belt_internalAVLtree.maxUndefined;
-
 let get = Belt_internalMapInt.get;
 
-let getUndefined = Belt_internalMapInt.getUndefined;
-
 let getWithDefault = Belt_internalMapInt.getWithDefault;
 
 let getExn = Belt_internalMapInt.getOrThrow;
@@ -271,15 +261,10 @@ export {
   keysToArray,
   valuesToArray,
   minKey,
-  minKeyUndefined,
   maxKey,
-  maxKeyUndefined,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getWithDefault,
   getExn,
   getOrThrow,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MapString.mjs b/packages/@rescript/runtime/lib/es6/Belt_MapString.mjs
index 07ea088642e..4eccd3c5a21 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MapString.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MapString.mjs
@@ -196,24 +196,14 @@ let valuesToArray = Belt_internalAVLtree.valuesToArray;
 
 let minKey = Belt_internalAVLtree.minKey;
 
-let minKeyUndefined = Belt_internalAVLtree.minKeyUndefined;
-
 let maxKey = Belt_internalAVLtree.maxKey;
 
-let maxKeyUndefined = Belt_internalAVLtree.maxKeyUndefined;
-
 let minimum = Belt_internalAVLtree.minimum;
 
-let minUndefined = Belt_internalAVLtree.minUndefined;
-
 let maximum = Belt_internalAVLtree.maximum;
 
-let maxUndefined = Belt_internalAVLtree.maxUndefined;
-
 let get = Belt_internalMapString.get;
 
-let getUndefined = Belt_internalMapString.getUndefined;
-
 let getWithDefault = Belt_internalMapString.getWithDefault;
 
 let getExn = Belt_internalMapString.getOrThrow;
@@ -271,15 +261,10 @@ export {
   keysToArray,
   valuesToArray,
   minKey,
-  minKeyUndefined,
   maxKey,
-  maxKeyUndefined,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getWithDefault,
   getExn,
   getOrThrow,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableMap.mjs b/packages/@rescript/runtime/lib/es6/Belt_MutableMap.mjs
index 18c824ed5dd..6904df72a89 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableMap.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MutableMap.mjs
@@ -152,34 +152,18 @@ function minKey(m) {
   return Belt_internalAVLtree.minKey(m.data);
 }
 
-function minKeyUndefined(m) {
-  return Belt_internalAVLtree.minKeyUndefined(m.data);
-}
-
 function maxKey(m) {
   return Belt_internalAVLtree.maxKey(m.data);
 }
 
-function maxKeyUndefined(m) {
-  return Belt_internalAVLtree.maxKeyUndefined(m.data);
-}
-
 function minimum(m) {
   return Belt_internalAVLtree.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_internalAVLtree.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_internalAVLtree.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_internalAVLtree.maxUndefined(m.data);
-}
-
 function forEach(d, f) {
   Belt_internalAVLtree.forEach(d.data, f);
 }
@@ -246,10 +230,6 @@ function get(m, x) {
   return Belt_internalAVLtree.get(m.data, x, m.cmp);
 }
 
-function getUndefined(m, x) {
-  return Belt_internalAVLtree.getUndefined(m.data, x, m.cmp);
-}
-
 function getWithDefault(m, x, def) {
   return Belt_internalAVLtree.getWithDefault(m.data, x, def, m.cmp);
 }
@@ -347,15 +327,10 @@ export {
   keysToArray,
   valuesToArray,
   minKey,
-  minKeyUndefined,
   maxKey,
-  maxKeyUndefined,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getWithDefault,
   getExn,
   getOrThrow,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableMapInt.mjs b/packages/@rescript/runtime/lib/es6/Belt_MutableMapInt.mjs
index 193f22c86b2..c7a5111a0f8 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableMapInt.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MutableMapInt.mjs
@@ -19,18 +19,10 @@ function clear(m) {
   m.data = undefined;
 }
 
-function minKeyUndefined(m) {
-  return Belt_internalAVLtree.minKeyUndefined(m.data);
-}
-
 function minKey(m) {
   return Belt_internalAVLtree.minKey(m.data);
 }
 
-function maxKeyUndefined(m) {
-  return Belt_internalAVLtree.maxKeyUndefined(m.data);
-}
-
 function maxKey(m) {
   return Belt_internalAVLtree.maxKey(m.data);
 }
@@ -39,18 +31,10 @@ function minimum(m) {
   return Belt_internalAVLtree.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_internalAVLtree.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_internalAVLtree.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_internalAVLtree.maxUndefined(m.data);
-}
-
 function set(m, k, v) {
   let old_data = m.data;
   let v$1 = Belt_internalMapInt.addMutate(old_data, k, v);
@@ -260,10 +244,6 @@ function get(d, x) {
   return Belt_internalMapInt.get(d.data, x);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalMapInt.getUndefined(d.data, x);
-}
-
 function getWithDefault(d, x, def) {
   return Belt_internalMapInt.getWithDefault(d.data, x, def);
 }
@@ -316,15 +296,10 @@ export {
   keysToArray,
   valuesToArray,
   minKey,
-  minKeyUndefined,
   maxKey,
-  maxKeyUndefined,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getWithDefault,
   getExn,
   getOrThrow,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableMapString.mjs b/packages/@rescript/runtime/lib/es6/Belt_MutableMapString.mjs
index 55d6ff1ab9e..12c23b010ba 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableMapString.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MutableMapString.mjs
@@ -19,18 +19,10 @@ function clear(m) {
   m.data = undefined;
 }
 
-function minKeyUndefined(m) {
-  return Belt_internalAVLtree.minKeyUndefined(m.data);
-}
-
 function minKey(m) {
   return Belt_internalAVLtree.minKey(m.data);
 }
 
-function maxKeyUndefined(m) {
-  return Belt_internalAVLtree.maxKeyUndefined(m.data);
-}
-
 function maxKey(m) {
   return Belt_internalAVLtree.maxKey(m.data);
 }
@@ -39,18 +31,10 @@ function minimum(m) {
   return Belt_internalAVLtree.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_internalAVLtree.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_internalAVLtree.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_internalAVLtree.maxUndefined(m.data);
-}
-
 function set(m, k, v) {
   let old_data = m.data;
   let v$1 = Belt_internalMapString.addMutate(old_data, k, v);
@@ -260,10 +244,6 @@ function get(d, x) {
   return Belt_internalMapString.get(d.data, x);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalMapString.getUndefined(d.data, x);
-}
-
 function getWithDefault(d, x, def) {
   return Belt_internalMapString.getWithDefault(d.data, x, def);
 }
@@ -316,15 +296,10 @@ export {
   keysToArray,
   valuesToArray,
   minKey,
-  minKeyUndefined,
   maxKey,
-  maxKeyUndefined,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getWithDefault,
   getExn,
   getOrThrow,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableQueue.mjs b/packages/@rescript/runtime/lib/es6/Belt_MutableQueue.mjs
index f9b1b6ba05e..2640eed1e5c 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableQueue.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MutableQueue.mjs
@@ -40,13 +40,6 @@ function peek(q) {
   }
 }
 
-function peekUndefined(q) {
-  let v = q.first;
-  if (v !== undefined) {
-    return v.content;
-  }
-}
-
 function peekOrThrow(q) {
   let v = q.first;
   if (v !== undefined) {
@@ -93,22 +86,6 @@ function popOrThrow(q) {
   };
 }
 
-function popUndefined(q) {
-  let x = q.first;
-  if (x === undefined) {
-    return;
-  }
-  let next = x.next;
-  if (next === undefined) {
-    clear(q);
-    return x.content;
-  } else {
-    q.length = q.length - 1 | 0;
-    q.first = next;
-    return x.content;
-  }
-}
-
 function copy(q) {
   let qRes = {
     length: q.length,
@@ -275,11 +252,9 @@ export {
   fromArray,
   add,
   peek,
-  peekUndefined,
   peekExn,
   peekOrThrow,
   pop,
-  popUndefined,
   popExn,
   popOrThrow,
   copy,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableSet.mjs b/packages/@rescript/runtime/lib/es6/Belt_MutableSet.mjs
index a1864184afa..0f52938a482 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableSet.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MutableSet.mjs
@@ -199,18 +199,10 @@ function minimum(d) {
   return Belt_internalAVLset.minimum(d.data);
 }
 
-function minUndefined(d) {
-  return Belt_internalAVLset.minUndefined(d.data);
-}
-
 function maximum(d) {
   return Belt_internalAVLset.maximum(d.data);
 }
 
-function maxUndefined(d) {
-  return Belt_internalAVLset.maxUndefined(d.data);
-}
-
 function forEach(d, f) {
   Belt_internalAVLset.forEach(d.data, f);
 }
@@ -270,10 +262,6 @@ function get(d, x) {
   return Belt_internalAVLset.get(d.data, x, d.cmp);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalAVLset.getUndefined(d.data, x, d.cmp);
-}
-
 function getOrThrow(d, x) {
   return Belt_internalAVLset.getOrThrow(d.data, x, d.cmp);
 }
@@ -514,11 +502,8 @@ export {
   toList,
   toArray,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getExn,
   getOrThrow,
   split,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableSetInt.mjs b/packages/@rescript/runtime/lib/es6/Belt_MutableSetInt.mjs
index 0fbbb3ee47c..659782e9189 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableSetInt.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MutableSetInt.mjs
@@ -196,18 +196,10 @@ function minimum(d) {
   return Belt_internalAVLset.minimum(d.data);
 }
 
-function minUndefined(d) {
-  return Belt_internalAVLset.minUndefined(d.data);
-}
-
 function maximum(d) {
   return Belt_internalAVLset.maximum(d.data);
 }
 
-function maxUndefined(d) {
-  return Belt_internalAVLset.maxUndefined(d.data);
-}
-
 function forEach(d, f) {
   Belt_internalAVLset.forEach(d.data, f);
 }
@@ -264,10 +256,6 @@ function get(d, x) {
   return Belt_internalSetInt.get(d.data, x);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalSetInt.getUndefined(d.data, x);
-}
-
 function getOrThrow(d, x) {
   return Belt_internalSetInt.getOrThrow(d.data, x);
 }
@@ -477,11 +465,8 @@ export {
   toList,
   toArray,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getExn,
   getOrThrow,
   split,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableSetString.mjs b/packages/@rescript/runtime/lib/es6/Belt_MutableSetString.mjs
index f60a7d3ca23..f63cac40468 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableSetString.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MutableSetString.mjs
@@ -196,18 +196,10 @@ function minimum(d) {
   return Belt_internalAVLset.minimum(d.data);
 }
 
-function minUndefined(d) {
-  return Belt_internalAVLset.minUndefined(d.data);
-}
-
 function maximum(d) {
   return Belt_internalAVLset.maximum(d.data);
 }
 
-function maxUndefined(d) {
-  return Belt_internalAVLset.maxUndefined(d.data);
-}
-
 function forEach(d, f) {
   Belt_internalAVLset.forEach(d.data, f);
 }
@@ -264,10 +256,6 @@ function get(d, x) {
   return Belt_internalSetString.get(d.data, x);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalSetString.getUndefined(d.data, x);
-}
-
 function getOrThrow(d, x) {
   return Belt_internalSetString.getOrThrow(d.data, x);
 }
@@ -477,11 +465,8 @@ export {
   toList,
   toArray,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getExn,
   getOrThrow,
   split,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_MutableStack.mjs b/packages/@rescript/runtime/lib/es6/Belt_MutableStack.mjs
index 57580c102a4..25797286152 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_MutableStack.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_MutableStack.mjs
@@ -25,13 +25,6 @@ function push(s, x) {
   };
 }
 
-function topUndefined(s) {
-  let x = s.root;
-  if (x !== undefined) {
-    return x.head;
-  }
-}
-
 function top(s) {
   let x = s.root;
   if (x !== undefined) {
@@ -43,20 +36,24 @@ function isEmpty(s) {
   return s.root === undefined;
 }
 
-function popUndefined(s) {
+function pop(s) {
   let x = s.root;
   if (x !== undefined) {
     s.root = x.tail;
-    return x.head;
+    return Primitive_option.some(x.head);
   }
 }
 
-function pop(s) {
+function popOrThrow(s) {
   let x = s.root;
   if (x !== undefined) {
     s.root = x.tail;
-    return Primitive_option.some(x.head);
+    return x.head;
   }
+  throw {
+    RE_EXN_ID: "Not_found",
+    Error: new Error()
+  };
 }
 
 function size(s) {
@@ -114,9 +111,8 @@ export {
   clear,
   copy,
   push,
-  popUndefined,
   pop,
-  topUndefined,
+  popOrThrow,
   top,
   isEmpty,
   size,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_Set.mjs b/packages/@rescript/runtime/lib/es6/Belt_Set.mjs
index 36d576b8525..891ea58887a 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_Set.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_Set.mjs
@@ -176,26 +176,14 @@ function minimum(m) {
   return Belt_SetDict.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_SetDict.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_SetDict.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_SetDict.maxUndefined(m.data);
-}
-
 function get(m, e) {
   return Belt_SetDict.get(m.data, e, m.cmp);
 }
 
-function getUndefined(m, e) {
-  return Belt_SetDict.getUndefined(m.data, e, m.cmp);
-}
-
 function getOrThrow(m, e) {
   return Belt_SetDict.getOrThrow(m.data, e, m.cmp);
 }
@@ -288,11 +276,8 @@ export {
   toArray,
   toList,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getExn,
   getOrThrow,
   split,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SetDict.mjs b/packages/@rescript/runtime/lib/es6/Belt_SetDict.mjs
index 1991e3b4c73..538d266f6a0 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_SetDict.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_SetDict.mjs
@@ -304,16 +304,10 @@ let toArray = Belt_internalAVLset.toArray;
 
 let minimum = Belt_internalAVLset.minimum;
 
-let minUndefined = Belt_internalAVLset.minUndefined;
-
 let maximum = Belt_internalAVLset.maximum;
 
-let maxUndefined = Belt_internalAVLset.maxUndefined;
-
 let get = Belt_internalAVLset.get;
 
-let getUndefined = Belt_internalAVLset.getUndefined;
-
 let getExn = Belt_internalAVLset.getOrThrow;
 
 let getOrThrow = Belt_internalAVLset.getOrThrow;
@@ -352,11 +346,8 @@ export {
   toList,
   toArray,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getExn,
   getOrThrow,
   split,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SetInt.mjs b/packages/@rescript/runtime/lib/es6/Belt_SetInt.mjs
index 4d30ebbd2b3..81b93fc7ded 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_SetInt.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_SetInt.mjs
@@ -301,16 +301,10 @@ let toArray = Belt_internalAVLset.toArray;
 
 let minimum = Belt_internalAVLset.minimum;
 
-let minUndefined = Belt_internalAVLset.minUndefined;
-
 let maximum = Belt_internalAVLset.maximum;
 
-let maxUndefined = Belt_internalAVLset.maxUndefined;
-
 let get = Belt_internalSetInt.get;
 
-let getUndefined = Belt_internalSetInt.getUndefined;
-
 let getExn = Belt_internalSetInt.getOrThrow;
 
 let getOrThrow = Belt_internalSetInt.getOrThrow;
@@ -349,11 +343,8 @@ export {
   toList,
   toArray,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getExn,
   getOrThrow,
   split,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_SetString.mjs b/packages/@rescript/runtime/lib/es6/Belt_SetString.mjs
index a98e5ae040c..e2f2982d4ad 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_SetString.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_SetString.mjs
@@ -301,16 +301,10 @@ let toArray = Belt_internalAVLset.toArray;
 
 let minimum = Belt_internalAVLset.minimum;
 
-let minUndefined = Belt_internalAVLset.minUndefined;
-
 let maximum = Belt_internalAVLset.maximum;
 
-let maxUndefined = Belt_internalAVLset.maxUndefined;
-
 let get = Belt_internalSetString.get;
 
-let getUndefined = Belt_internalSetString.getUndefined;
-
 let getExn = Belt_internalSetString.getOrThrow;
 
 let getOrThrow = Belt_internalSetString.getOrThrow;
@@ -349,11 +343,8 @@ export {
   toList,
   toArray,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   get,
-  getUndefined,
   getExn,
   getOrThrow,
   split,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalAVLset.mjs b/packages/@rescript/runtime/lib/es6/Belt_internalAVLset.mjs
index 889662c2977..f679e28aaf3 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalAVLset.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_internalAVLset.mjs
@@ -100,12 +100,6 @@ function minimum(n) {
   }
 }
 
-function minUndefined(n) {
-  if (n !== undefined) {
-    return min0Aux(n);
-  }
-}
-
 function max0Aux(_n) {
   while (true) {
     let n = _n;
@@ -124,12 +118,6 @@ function maximum(n) {
   }
 }
 
-function maxUndefined(n) {
-  if (n !== undefined) {
-    return max0Aux(n);
-  }
-}
-
 function removeMinAuxWithRef(n, v) {
   let ln = n.l;
   if (ln !== undefined) {
@@ -350,7 +338,7 @@ function checkInvariantInternal(_v) {
         RE_EXN_ID: "Assert_failure",
         _1: [
           "Belt_internalAVLset.res",
-          292,
+          280,
           4
         ],
         Error: new Error()
@@ -668,22 +656,6 @@ function get(_n, x, cmp) {
   };
 }
 
-function getUndefined(_n, x, cmp) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.v;
-    let c = cmp(x, v);
-    if (c === 0) {
-      return v;
-    }
-    _n = c < 0 ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x, cmp) {
   while (true) {
     let n = _n;
@@ -842,9 +814,7 @@ export {
   bal,
   singleton,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   removeMinAuxWithRef,
   isEmpty,
   stackAllLeft,
@@ -872,7 +842,6 @@ export {
   eq,
   subset,
   get,
-  getUndefined,
   getOrThrow,
   fromArray,
   addMutate,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalAVLtree.mjs b/packages/@rescript/runtime/lib/es6/Belt_internalAVLtree.mjs
index 35886b05be6..6f5f86f0aee 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalAVLtree.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_internalAVLtree.mjs
@@ -122,12 +122,6 @@ function minKey(n) {
   }
 }
 
-function minKeyUndefined(n) {
-  if (n !== undefined) {
-    return minKey0Aux(n);
-  }
-}
-
 function maxKey0Aux(_n) {
   while (true) {
     let n = _n;
@@ -146,12 +140,6 @@ function maxKey(n) {
   }
 }
 
-function maxKeyUndefined(n) {
-  if (n !== undefined) {
-    return maxKey0Aux(n);
-  }
-}
-
 function minKV0Aux(_n) {
   while (true) {
     let n = _n;
@@ -173,12 +161,6 @@ function minimum(n) {
   }
 }
 
-function minUndefined(n) {
-  if (n !== undefined) {
-    return minKV0Aux(n);
-  }
-}
-
 function maxKV0Aux(_n) {
   while (true) {
     let n = _n;
@@ -200,12 +182,6 @@ function maximum(n) {
   }
 }
 
-function maxUndefined(n) {
-  if (n !== undefined) {
-    return maxKV0Aux(n);
-  }
-}
-
 function removeMinAuxWithRef(n, kr, vr) {
   let ln = n.l;
   if (ln !== undefined) {
@@ -542,7 +518,7 @@ function checkInvariantInternal(_v) {
         RE_EXN_ID: "Assert_failure",
         _1: [
           "Belt_internalAVLtree.res",
-          432,
+          408,
           4
         ],
         Error: new Error()
@@ -812,22 +788,6 @@ function get(_n, x, cmp) {
   };
 }
 
-function getUndefined(_n, x, cmp) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.k;
-    let c = cmp(x, v);
-    if (c === 0) {
-      return n.v;
-    }
-    _n = c < 0 ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x, cmp) {
   while (true) {
     let n = _n;
@@ -1014,13 +974,9 @@ export {
   singleton,
   updateValue,
   minKey,
-  minKeyUndefined,
   maxKey,
-  maxKeyUndefined,
   minimum,
-  minUndefined,
   maximum,
-  maxUndefined,
   removeMinAuxWithRef,
   isEmpty,
   stackAllLeft,
@@ -1051,7 +1007,6 @@ export {
   cmp,
   eq,
   get,
-  getUndefined,
   getWithDefault,
   getOrThrow,
   has,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalMapInt.mjs b/packages/@rescript/runtime/lib/es6/Belt_internalMapInt.mjs
index a31bfed334e..687fca236e3 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalMapInt.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_internalMapInt.mjs
@@ -36,21 +36,6 @@ function get(_n, x) {
   };
 }
 
-function getUndefined(_n, x) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.k;
-    if (x === v) {
-      return n.v;
-    }
-    _n = x < v ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x) {
   while (true) {
     let n = _n;
@@ -334,7 +319,6 @@ export {
   S,
   add,
   get,
-  getUndefined,
   getOrThrow,
   getWithDefault,
   has,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalMapString.mjs b/packages/@rescript/runtime/lib/es6/Belt_internalMapString.mjs
index cc06d894f3b..8db48ead6a5 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalMapString.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_internalMapString.mjs
@@ -36,21 +36,6 @@ function get(_n, x) {
   };
 }
 
-function getUndefined(_n, x) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.k;
-    if (x === v) {
-      return n.v;
-    }
-    _n = x < v ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x) {
   while (true) {
     let n = _n;
@@ -334,7 +319,6 @@ export {
   S,
   add,
   get,
-  getUndefined,
   getOrThrow,
   getWithDefault,
   has,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalSetInt.mjs b/packages/@rescript/runtime/lib/es6/Belt_internalSetInt.mjs
index 702bc6c9a68..ccaeefcde89 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalSetInt.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_internalSetInt.mjs
@@ -115,21 +115,6 @@ function get(_n, x) {
   };
 }
 
-function getUndefined(_n, x) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.v;
-    if (x === v) {
-      return v;
-    }
-    _n = x < v ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x) {
   while (true) {
     let n = _n;
@@ -201,7 +186,6 @@ export {
   eq,
   subset,
   get,
-  getUndefined,
   getOrThrow,
   addMutate,
   fromArray,
diff --git a/packages/@rescript/runtime/lib/es6/Belt_internalSetString.mjs b/packages/@rescript/runtime/lib/es6/Belt_internalSetString.mjs
index aa33452bdfa..d0173f633db 100644
--- a/packages/@rescript/runtime/lib/es6/Belt_internalSetString.mjs
+++ b/packages/@rescript/runtime/lib/es6/Belt_internalSetString.mjs
@@ -115,21 +115,6 @@ function get(_n, x) {
   };
 }
 
-function getUndefined(_n, x) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.v;
-    if (x === v) {
-      return v;
-    }
-    _n = x < v ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x) {
   while (true) {
     let n = _n;
@@ -201,7 +186,6 @@ export {
   eq,
   subset,
   get,
-  getUndefined,
   getOrThrow,
   addMutate,
   fromArray,
diff --git a/packages/@rescript/runtime/lib/js/Belt_Array.cjs b/packages/@rescript/runtime/lib/js/Belt_Array.cjs
index 9289d8b2599..cbc613a08fc 100644
--- a/packages/@rescript/runtime/lib/js/Belt_Array.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_Array.cjs
@@ -15,7 +15,7 @@ function getOrThrow(arr, i) {
       RE_EXN_ID: "Assert_failure",
       _1: [
         "Belt_Array.res",
-        29,
+        27,
         2
       ],
       Error: new Error()
@@ -39,7 +39,7 @@ function setOrThrow(arr, i, v) {
       RE_EXN_ID: "Assert_failure",
       _1: [
         "Belt_Array.res",
-        44,
+        42,
         2
       ],
       Error: new Error()
diff --git a/packages/@rescript/runtime/lib/js/Belt_Map.cjs b/packages/@rescript/runtime/lib/js/Belt_Map.cjs
index 2e3d073863a..5221fd8c74d 100644
--- a/packages/@rescript/runtime/lib/js/Belt_Map.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_Map.cjs
@@ -175,42 +175,22 @@ function minKey(m) {
   return Belt_MapDict.minKey(m.data);
 }
 
-function minKeyUndefined(m) {
-  return Belt_MapDict.minKeyUndefined(m.data);
-}
-
 function maxKey(m) {
   return Belt_MapDict.maxKey(m.data);
 }
 
-function maxKeyUndefined(m) {
-  return Belt_MapDict.maxKeyUndefined(m.data);
-}
-
 function minimum(m) {
   return Belt_MapDict.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_MapDict.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_MapDict.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_MapDict.maxUndefined(m.data);
-}
-
 function get(map, x) {
   return Belt_MapDict.get(map.data, x, map.cmp);
 }
 
-function getUndefined(map, x) {
-  return Belt_MapDict.getUndefined(map.data, x, map.cmp);
-}
-
 function getWithDefault(map, x, def) {
   return Belt_MapDict.getWithDefault(map.data, x, def, map.cmp);
 }
@@ -314,15 +294,10 @@ exports.fromArray = fromArray;
 exports.keysToArray = keysToArray;
 exports.valuesToArray = valuesToArray;
 exports.minKey = minKey;
-exports.minKeyUndefined = minKeyUndefined;
 exports.maxKey = maxKey;
-exports.maxKeyUndefined = maxKeyUndefined;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getWithDefault = getWithDefault;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MapDict.cjs b/packages/@rescript/runtime/lib/js/Belt_MapDict.cjs
index 498dfa0a960..2da494c41ec 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MapDict.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MapDict.cjs
@@ -304,24 +304,14 @@ let valuesToArray = Belt_internalAVLtree.valuesToArray;
 
 let minKey = Belt_internalAVLtree.minKey;
 
-let minKeyUndefined = Belt_internalAVLtree.minKeyUndefined;
-
 let maxKey = Belt_internalAVLtree.maxKey;
 
-let maxKeyUndefined = Belt_internalAVLtree.maxKeyUndefined;
-
 let minimum = Belt_internalAVLtree.minimum;
 
-let minUndefined = Belt_internalAVLtree.minUndefined;
-
 let maximum = Belt_internalAVLtree.maximum;
 
-let maxUndefined = Belt_internalAVLtree.maxUndefined;
-
 let get = Belt_internalAVLtree.get;
 
-let getUndefined = Belt_internalAVLtree.getUndefined;
-
 let getWithDefault = Belt_internalAVLtree.getWithDefault;
 
 let getExn = Belt_internalAVLtree.getOrThrow;
@@ -374,15 +364,10 @@ exports.fromArray = fromArray;
 exports.keysToArray = keysToArray;
 exports.valuesToArray = valuesToArray;
 exports.minKey = minKey;
-exports.minKeyUndefined = minKeyUndefined;
 exports.maxKey = maxKey;
-exports.maxKeyUndefined = maxKeyUndefined;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getWithDefault = getWithDefault;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MapInt.cjs b/packages/@rescript/runtime/lib/js/Belt_MapInt.cjs
index f7e6a1a53e7..468f503562c 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MapInt.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MapInt.cjs
@@ -196,24 +196,14 @@ let valuesToArray = Belt_internalAVLtree.valuesToArray;
 
 let minKey = Belt_internalAVLtree.minKey;
 
-let minKeyUndefined = Belt_internalAVLtree.minKeyUndefined;
-
 let maxKey = Belt_internalAVLtree.maxKey;
 
-let maxKeyUndefined = Belt_internalAVLtree.maxKeyUndefined;
-
 let minimum = Belt_internalAVLtree.minimum;
 
-let minUndefined = Belt_internalAVLtree.minUndefined;
-
 let maximum = Belt_internalAVLtree.maximum;
 
-let maxUndefined = Belt_internalAVLtree.maxUndefined;
-
 let get = Belt_internalMapInt.get;
 
-let getUndefined = Belt_internalMapInt.getUndefined;
-
 let getWithDefault = Belt_internalMapInt.getWithDefault;
 
 let getExn = Belt_internalMapInt.getOrThrow;
@@ -270,15 +260,10 @@ exports.fromArray = fromArray;
 exports.keysToArray = keysToArray;
 exports.valuesToArray = valuesToArray;
 exports.minKey = minKey;
-exports.minKeyUndefined = minKeyUndefined;
 exports.maxKey = maxKey;
-exports.maxKeyUndefined = maxKeyUndefined;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getWithDefault = getWithDefault;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MapString.cjs b/packages/@rescript/runtime/lib/js/Belt_MapString.cjs
index 1de8dd3a5ff..e68674e64e4 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MapString.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MapString.cjs
@@ -196,24 +196,14 @@ let valuesToArray = Belt_internalAVLtree.valuesToArray;
 
 let minKey = Belt_internalAVLtree.minKey;
 
-let minKeyUndefined = Belt_internalAVLtree.minKeyUndefined;
-
 let maxKey = Belt_internalAVLtree.maxKey;
 
-let maxKeyUndefined = Belt_internalAVLtree.maxKeyUndefined;
-
 let minimum = Belt_internalAVLtree.minimum;
 
-let minUndefined = Belt_internalAVLtree.minUndefined;
-
 let maximum = Belt_internalAVLtree.maximum;
 
-let maxUndefined = Belt_internalAVLtree.maxUndefined;
-
 let get = Belt_internalMapString.get;
 
-let getUndefined = Belt_internalMapString.getUndefined;
-
 let getWithDefault = Belt_internalMapString.getWithDefault;
 
 let getExn = Belt_internalMapString.getOrThrow;
@@ -270,15 +260,10 @@ exports.fromArray = fromArray;
 exports.keysToArray = keysToArray;
 exports.valuesToArray = valuesToArray;
 exports.minKey = minKey;
-exports.minKeyUndefined = minKeyUndefined;
 exports.maxKey = maxKey;
-exports.maxKeyUndefined = maxKeyUndefined;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getWithDefault = getWithDefault;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableMap.cjs b/packages/@rescript/runtime/lib/js/Belt_MutableMap.cjs
index ea2f4c3d703..e1c5bd40e81 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableMap.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MutableMap.cjs
@@ -152,34 +152,18 @@ function minKey(m) {
   return Belt_internalAVLtree.minKey(m.data);
 }
 
-function minKeyUndefined(m) {
-  return Belt_internalAVLtree.minKeyUndefined(m.data);
-}
-
 function maxKey(m) {
   return Belt_internalAVLtree.maxKey(m.data);
 }
 
-function maxKeyUndefined(m) {
-  return Belt_internalAVLtree.maxKeyUndefined(m.data);
-}
-
 function minimum(m) {
   return Belt_internalAVLtree.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_internalAVLtree.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_internalAVLtree.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_internalAVLtree.maxUndefined(m.data);
-}
-
 function forEach(d, f) {
   Belt_internalAVLtree.forEach(d.data, f);
 }
@@ -246,10 +230,6 @@ function get(m, x) {
   return Belt_internalAVLtree.get(m.data, x, m.cmp);
 }
 
-function getUndefined(m, x) {
-  return Belt_internalAVLtree.getUndefined(m.data, x, m.cmp);
-}
-
 function getWithDefault(m, x, def) {
   return Belt_internalAVLtree.getWithDefault(m.data, x, def, m.cmp);
 }
@@ -346,15 +326,10 @@ exports.fromArray = fromArray;
 exports.keysToArray = keysToArray;
 exports.valuesToArray = valuesToArray;
 exports.minKey = minKey;
-exports.minKeyUndefined = minKeyUndefined;
 exports.maxKey = maxKey;
-exports.maxKeyUndefined = maxKeyUndefined;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getWithDefault = getWithDefault;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableMapInt.cjs b/packages/@rescript/runtime/lib/js/Belt_MutableMapInt.cjs
index c90d8b05710..bb296711ee2 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableMapInt.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MutableMapInt.cjs
@@ -19,18 +19,10 @@ function clear(m) {
   m.data = undefined;
 }
 
-function minKeyUndefined(m) {
-  return Belt_internalAVLtree.minKeyUndefined(m.data);
-}
-
 function minKey(m) {
   return Belt_internalAVLtree.minKey(m.data);
 }
 
-function maxKeyUndefined(m) {
-  return Belt_internalAVLtree.maxKeyUndefined(m.data);
-}
-
 function maxKey(m) {
   return Belt_internalAVLtree.maxKey(m.data);
 }
@@ -39,18 +31,10 @@ function minimum(m) {
   return Belt_internalAVLtree.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_internalAVLtree.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_internalAVLtree.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_internalAVLtree.maxUndefined(m.data);
-}
-
 function set(m, k, v) {
   let old_data = m.data;
   let v$1 = Belt_internalMapInt.addMutate(old_data, k, v);
@@ -260,10 +244,6 @@ function get(d, x) {
   return Belt_internalMapInt.get(d.data, x);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalMapInt.getUndefined(d.data, x);
-}
-
 function getWithDefault(d, x, def) {
   return Belt_internalMapInt.getWithDefault(d.data, x, def);
 }
@@ -315,15 +295,10 @@ exports.fromArray = fromArray;
 exports.keysToArray = keysToArray;
 exports.valuesToArray = valuesToArray;
 exports.minKey = minKey;
-exports.minKeyUndefined = minKeyUndefined;
 exports.maxKey = maxKey;
-exports.maxKeyUndefined = maxKeyUndefined;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getWithDefault = getWithDefault;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableMapString.cjs b/packages/@rescript/runtime/lib/js/Belt_MutableMapString.cjs
index a096bb0f324..27dabb44a7b 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableMapString.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MutableMapString.cjs
@@ -19,18 +19,10 @@ function clear(m) {
   m.data = undefined;
 }
 
-function minKeyUndefined(m) {
-  return Belt_internalAVLtree.minKeyUndefined(m.data);
-}
-
 function minKey(m) {
   return Belt_internalAVLtree.minKey(m.data);
 }
 
-function maxKeyUndefined(m) {
-  return Belt_internalAVLtree.maxKeyUndefined(m.data);
-}
-
 function maxKey(m) {
   return Belt_internalAVLtree.maxKey(m.data);
 }
@@ -39,18 +31,10 @@ function minimum(m) {
   return Belt_internalAVLtree.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_internalAVLtree.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_internalAVLtree.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_internalAVLtree.maxUndefined(m.data);
-}
-
 function set(m, k, v) {
   let old_data = m.data;
   let v$1 = Belt_internalMapString.addMutate(old_data, k, v);
@@ -260,10 +244,6 @@ function get(d, x) {
   return Belt_internalMapString.get(d.data, x);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalMapString.getUndefined(d.data, x);
-}
-
 function getWithDefault(d, x, def) {
   return Belt_internalMapString.getWithDefault(d.data, x, def);
 }
@@ -315,15 +295,10 @@ exports.fromArray = fromArray;
 exports.keysToArray = keysToArray;
 exports.valuesToArray = valuesToArray;
 exports.minKey = minKey;
-exports.minKeyUndefined = minKeyUndefined;
 exports.maxKey = maxKey;
-exports.maxKeyUndefined = maxKeyUndefined;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getWithDefault = getWithDefault;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableQueue.cjs b/packages/@rescript/runtime/lib/js/Belt_MutableQueue.cjs
index 6586ca1e3e8..6fd919d3f1b 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableQueue.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MutableQueue.cjs
@@ -40,13 +40,6 @@ function peek(q) {
   }
 }
 
-function peekUndefined(q) {
-  let v = q.first;
-  if (v !== undefined) {
-    return v.content;
-  }
-}
-
 function peekOrThrow(q) {
   let v = q.first;
   if (v !== undefined) {
@@ -93,22 +86,6 @@ function popOrThrow(q) {
   };
 }
 
-function popUndefined(q) {
-  let x = q.first;
-  if (x === undefined) {
-    return;
-  }
-  let next = x.next;
-  if (next === undefined) {
-    clear(q);
-    return x.content;
-  } else {
-    q.length = q.length - 1 | 0;
-    q.first = next;
-    return x.content;
-  }
-}
-
 function copy(q) {
   let qRes = {
     length: q.length,
@@ -274,11 +251,9 @@ exports.isEmpty = isEmpty;
 exports.fromArray = fromArray;
 exports.add = add;
 exports.peek = peek;
-exports.peekUndefined = peekUndefined;
 exports.peekExn = peekExn;
 exports.peekOrThrow = peekOrThrow;
 exports.pop = pop;
-exports.popUndefined = popUndefined;
 exports.popExn = popExn;
 exports.popOrThrow = popOrThrow;
 exports.copy = copy;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableSet.cjs b/packages/@rescript/runtime/lib/js/Belt_MutableSet.cjs
index 33878ffa9b8..2d44004d261 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableSet.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MutableSet.cjs
@@ -199,18 +199,10 @@ function minimum(d) {
   return Belt_internalAVLset.minimum(d.data);
 }
 
-function minUndefined(d) {
-  return Belt_internalAVLset.minUndefined(d.data);
-}
-
 function maximum(d) {
   return Belt_internalAVLset.maximum(d.data);
 }
 
-function maxUndefined(d) {
-  return Belt_internalAVLset.maxUndefined(d.data);
-}
-
 function forEach(d, f) {
   Belt_internalAVLset.forEach(d.data, f);
 }
@@ -270,10 +262,6 @@ function get(d, x) {
   return Belt_internalAVLset.get(d.data, x, d.cmp);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalAVLset.getUndefined(d.data, x, d.cmp);
-}
-
 function getOrThrow(d, x) {
   return Belt_internalAVLset.getOrThrow(d.data, x, d.cmp);
 }
@@ -513,11 +501,8 @@ exports.size = size;
 exports.toList = toList;
 exports.toArray = toArray;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
 exports.split = split;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableSetInt.cjs b/packages/@rescript/runtime/lib/js/Belt_MutableSetInt.cjs
index c33abad371c..ef9d822b31e 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableSetInt.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MutableSetInt.cjs
@@ -196,18 +196,10 @@ function minimum(d) {
   return Belt_internalAVLset.minimum(d.data);
 }
 
-function minUndefined(d) {
-  return Belt_internalAVLset.minUndefined(d.data);
-}
-
 function maximum(d) {
   return Belt_internalAVLset.maximum(d.data);
 }
 
-function maxUndefined(d) {
-  return Belt_internalAVLset.maxUndefined(d.data);
-}
-
 function forEach(d, f) {
   Belt_internalAVLset.forEach(d.data, f);
 }
@@ -264,10 +256,6 @@ function get(d, x) {
   return Belt_internalSetInt.get(d.data, x);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalSetInt.getUndefined(d.data, x);
-}
-
 function getOrThrow(d, x) {
   return Belt_internalSetInt.getOrThrow(d.data, x);
 }
@@ -476,11 +464,8 @@ exports.size = size;
 exports.toList = toList;
 exports.toArray = toArray;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
 exports.split = split;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableSetString.cjs b/packages/@rescript/runtime/lib/js/Belt_MutableSetString.cjs
index 4653de27b78..b1abaccad1a 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableSetString.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MutableSetString.cjs
@@ -196,18 +196,10 @@ function minimum(d) {
   return Belt_internalAVLset.minimum(d.data);
 }
 
-function minUndefined(d) {
-  return Belt_internalAVLset.minUndefined(d.data);
-}
-
 function maximum(d) {
   return Belt_internalAVLset.maximum(d.data);
 }
 
-function maxUndefined(d) {
-  return Belt_internalAVLset.maxUndefined(d.data);
-}
-
 function forEach(d, f) {
   Belt_internalAVLset.forEach(d.data, f);
 }
@@ -264,10 +256,6 @@ function get(d, x) {
   return Belt_internalSetString.get(d.data, x);
 }
 
-function getUndefined(d, x) {
-  return Belt_internalSetString.getUndefined(d.data, x);
-}
-
 function getOrThrow(d, x) {
   return Belt_internalSetString.getOrThrow(d.data, x);
 }
@@ -476,11 +464,8 @@ exports.size = size;
 exports.toList = toList;
 exports.toArray = toArray;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
 exports.split = split;
diff --git a/packages/@rescript/runtime/lib/js/Belt_MutableStack.cjs b/packages/@rescript/runtime/lib/js/Belt_MutableStack.cjs
index 91e208223c2..d5899040684 100644
--- a/packages/@rescript/runtime/lib/js/Belt_MutableStack.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_MutableStack.cjs
@@ -25,13 +25,6 @@ function push(s, x) {
   };
 }
 
-function topUndefined(s) {
-  let x = s.root;
-  if (x !== undefined) {
-    return x.head;
-  }
-}
-
 function top(s) {
   let x = s.root;
   if (x !== undefined) {
@@ -43,20 +36,24 @@ function isEmpty(s) {
   return s.root === undefined;
 }
 
-function popUndefined(s) {
+function pop(s) {
   let x = s.root;
   if (x !== undefined) {
     s.root = x.tail;
-    return x.head;
+    return Primitive_option.some(x.head);
   }
 }
 
-function pop(s) {
+function popOrThrow(s) {
   let x = s.root;
   if (x !== undefined) {
     s.root = x.tail;
-    return Primitive_option.some(x.head);
+    return x.head;
   }
+  throw {
+    RE_EXN_ID: "Not_found",
+    Error: new Error()
+  };
 }
 
 function size(s) {
@@ -113,9 +110,8 @@ exports.make = make;
 exports.clear = clear;
 exports.copy = copy;
 exports.push = push;
-exports.popUndefined = popUndefined;
 exports.pop = pop;
-exports.topUndefined = topUndefined;
+exports.popOrThrow = popOrThrow;
 exports.top = top;
 exports.isEmpty = isEmpty;
 exports.size = size;
diff --git a/packages/@rescript/runtime/lib/js/Belt_Set.cjs b/packages/@rescript/runtime/lib/js/Belt_Set.cjs
index 0b5b90664ba..4211817ed5e 100644
--- a/packages/@rescript/runtime/lib/js/Belt_Set.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_Set.cjs
@@ -176,26 +176,14 @@ function minimum(m) {
   return Belt_SetDict.minimum(m.data);
 }
 
-function minUndefined(m) {
-  return Belt_SetDict.minUndefined(m.data);
-}
-
 function maximum(m) {
   return Belt_SetDict.maximum(m.data);
 }
 
-function maxUndefined(m) {
-  return Belt_SetDict.maxUndefined(m.data);
-}
-
 function get(m, e) {
   return Belt_SetDict.get(m.data, e, m.cmp);
 }
 
-function getUndefined(m, e) {
-  return Belt_SetDict.getUndefined(m.data, e, m.cmp);
-}
-
 function getOrThrow(m, e) {
   return Belt_SetDict.getOrThrow(m.data, e, m.cmp);
 }
@@ -287,11 +275,8 @@ exports.size = size;
 exports.toArray = toArray;
 exports.toList = toList;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
 exports.split = split;
diff --git a/packages/@rescript/runtime/lib/js/Belt_SetDict.cjs b/packages/@rescript/runtime/lib/js/Belt_SetDict.cjs
index 24874407038..55849d49cd4 100644
--- a/packages/@rescript/runtime/lib/js/Belt_SetDict.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_SetDict.cjs
@@ -304,16 +304,10 @@ let toArray = Belt_internalAVLset.toArray;
 
 let minimum = Belt_internalAVLset.minimum;
 
-let minUndefined = Belt_internalAVLset.minUndefined;
-
 let maximum = Belt_internalAVLset.maximum;
 
-let maxUndefined = Belt_internalAVLset.maxUndefined;
-
 let get = Belt_internalAVLset.get;
 
-let getUndefined = Belt_internalAVLset.getUndefined;
-
 let getExn = Belt_internalAVLset.getOrThrow;
 
 let getOrThrow = Belt_internalAVLset.getOrThrow;
@@ -351,11 +345,8 @@ exports.size = size;
 exports.toList = toList;
 exports.toArray = toArray;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
 exports.split = split;
diff --git a/packages/@rescript/runtime/lib/js/Belt_SetInt.cjs b/packages/@rescript/runtime/lib/js/Belt_SetInt.cjs
index 5a27ab8cece..6dba04e05ff 100644
--- a/packages/@rescript/runtime/lib/js/Belt_SetInt.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_SetInt.cjs
@@ -301,16 +301,10 @@ let toArray = Belt_internalAVLset.toArray;
 
 let minimum = Belt_internalAVLset.minimum;
 
-let minUndefined = Belt_internalAVLset.minUndefined;
-
 let maximum = Belt_internalAVLset.maximum;
 
-let maxUndefined = Belt_internalAVLset.maxUndefined;
-
 let get = Belt_internalSetInt.get;
 
-let getUndefined = Belt_internalSetInt.getUndefined;
-
 let getExn = Belt_internalSetInt.getOrThrow;
 
 let getOrThrow = Belt_internalSetInt.getOrThrow;
@@ -348,11 +342,8 @@ exports.size = size;
 exports.toList = toList;
 exports.toArray = toArray;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
 exports.split = split;
diff --git a/packages/@rescript/runtime/lib/js/Belt_SetString.cjs b/packages/@rescript/runtime/lib/js/Belt_SetString.cjs
index a449b02df90..a30162bdc04 100644
--- a/packages/@rescript/runtime/lib/js/Belt_SetString.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_SetString.cjs
@@ -301,16 +301,10 @@ let toArray = Belt_internalAVLset.toArray;
 
 let minimum = Belt_internalAVLset.minimum;
 
-let minUndefined = Belt_internalAVLset.minUndefined;
-
 let maximum = Belt_internalAVLset.maximum;
 
-let maxUndefined = Belt_internalAVLset.maxUndefined;
-
 let get = Belt_internalSetString.get;
 
-let getUndefined = Belt_internalSetString.getUndefined;
-
 let getExn = Belt_internalSetString.getOrThrow;
 
 let getOrThrow = Belt_internalSetString.getOrThrow;
@@ -348,11 +342,8 @@ exports.size = size;
 exports.toList = toList;
 exports.toArray = toArray;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getExn = getExn;
 exports.getOrThrow = getOrThrow;
 exports.split = split;
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalAVLset.cjs b/packages/@rescript/runtime/lib/js/Belt_internalAVLset.cjs
index dc4a079e645..50626ea185f 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalAVLset.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_internalAVLset.cjs
@@ -100,12 +100,6 @@ function minimum(n) {
   }
 }
 
-function minUndefined(n) {
-  if (n !== undefined) {
-    return min0Aux(n);
-  }
-}
-
 function max0Aux(_n) {
   while (true) {
     let n = _n;
@@ -124,12 +118,6 @@ function maximum(n) {
   }
 }
 
-function maxUndefined(n) {
-  if (n !== undefined) {
-    return max0Aux(n);
-  }
-}
-
 function removeMinAuxWithRef(n, v) {
   let ln = n.l;
   if (ln !== undefined) {
@@ -350,7 +338,7 @@ function checkInvariantInternal(_v) {
         RE_EXN_ID: "Assert_failure",
         _1: [
           "Belt_internalAVLset.res",
-          292,
+          280,
           4
         ],
         Error: new Error()
@@ -668,22 +656,6 @@ function get(_n, x, cmp) {
   };
 }
 
-function getUndefined(_n, x, cmp) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.v;
-    let c = cmp(x, v);
-    if (c === 0) {
-      return v;
-    }
-    _n = c < 0 ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x, cmp) {
   while (true) {
     let n = _n;
@@ -841,9 +813,7 @@ exports.create = create;
 exports.bal = bal;
 exports.singleton = singleton;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.removeMinAuxWithRef = removeMinAuxWithRef;
 exports.isEmpty = isEmpty;
 exports.stackAllLeft = stackAllLeft;
@@ -871,7 +841,6 @@ exports.cmp = cmp;
 exports.eq = eq;
 exports.subset = subset;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getOrThrow = getOrThrow;
 exports.fromArray = fromArray;
 exports.addMutate = addMutate;
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalAVLtree.cjs b/packages/@rescript/runtime/lib/js/Belt_internalAVLtree.cjs
index 6c2c8919249..1192eb13d88 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalAVLtree.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_internalAVLtree.cjs
@@ -122,12 +122,6 @@ function minKey(n) {
   }
 }
 
-function minKeyUndefined(n) {
-  if (n !== undefined) {
-    return minKey0Aux(n);
-  }
-}
-
 function maxKey0Aux(_n) {
   while (true) {
     let n = _n;
@@ -146,12 +140,6 @@ function maxKey(n) {
   }
 }
 
-function maxKeyUndefined(n) {
-  if (n !== undefined) {
-    return maxKey0Aux(n);
-  }
-}
-
 function minKV0Aux(_n) {
   while (true) {
     let n = _n;
@@ -173,12 +161,6 @@ function minimum(n) {
   }
 }
 
-function minUndefined(n) {
-  if (n !== undefined) {
-    return minKV0Aux(n);
-  }
-}
-
 function maxKV0Aux(_n) {
   while (true) {
     let n = _n;
@@ -200,12 +182,6 @@ function maximum(n) {
   }
 }
 
-function maxUndefined(n) {
-  if (n !== undefined) {
-    return maxKV0Aux(n);
-  }
-}
-
 function removeMinAuxWithRef(n, kr, vr) {
   let ln = n.l;
   if (ln !== undefined) {
@@ -542,7 +518,7 @@ function checkInvariantInternal(_v) {
         RE_EXN_ID: "Assert_failure",
         _1: [
           "Belt_internalAVLtree.res",
-          432,
+          408,
           4
         ],
         Error: new Error()
@@ -812,22 +788,6 @@ function get(_n, x, cmp) {
   };
 }
 
-function getUndefined(_n, x, cmp) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.k;
-    let c = cmp(x, v);
-    if (c === 0) {
-      return n.v;
-    }
-    _n = c < 0 ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x, cmp) {
   while (true) {
     let n = _n;
@@ -1013,13 +973,9 @@ exports.bal = bal;
 exports.singleton = singleton;
 exports.updateValue = updateValue;
 exports.minKey = minKey;
-exports.minKeyUndefined = minKeyUndefined;
 exports.maxKey = maxKey;
-exports.maxKeyUndefined = maxKeyUndefined;
 exports.minimum = minimum;
-exports.minUndefined = minUndefined;
 exports.maximum = maximum;
-exports.maxUndefined = maxUndefined;
 exports.removeMinAuxWithRef = removeMinAuxWithRef;
 exports.isEmpty = isEmpty;
 exports.stackAllLeft = stackAllLeft;
@@ -1050,7 +1006,6 @@ exports.fromSortedArrayUnsafe = fromSortedArrayUnsafe;
 exports.cmp = cmp;
 exports.eq = eq;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getWithDefault = getWithDefault;
 exports.getOrThrow = getOrThrow;
 exports.has = has;
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalMapInt.cjs b/packages/@rescript/runtime/lib/js/Belt_internalMapInt.cjs
index 54355b22528..1c09a9c4e1b 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalMapInt.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_internalMapInt.cjs
@@ -36,21 +36,6 @@ function get(_n, x) {
   };
 }
 
-function getUndefined(_n, x) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.k;
-    if (x === v) {
-      return n.v;
-    }
-    _n = x < v ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x) {
   while (true) {
     let n = _n;
@@ -333,7 +318,6 @@ exports.A = A;
 exports.S = S;
 exports.add = add;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getOrThrow = getOrThrow;
 exports.getWithDefault = getWithDefault;
 exports.has = has;
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalMapString.cjs b/packages/@rescript/runtime/lib/js/Belt_internalMapString.cjs
index bb73f3a141c..1ff5fa3cb08 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalMapString.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_internalMapString.cjs
@@ -36,21 +36,6 @@ function get(_n, x) {
   };
 }
 
-function getUndefined(_n, x) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.k;
-    if (x === v) {
-      return n.v;
-    }
-    _n = x < v ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x) {
   while (true) {
     let n = _n;
@@ -333,7 +318,6 @@ exports.A = A;
 exports.S = S;
 exports.add = add;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getOrThrow = getOrThrow;
 exports.getWithDefault = getWithDefault;
 exports.has = has;
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalSetInt.cjs b/packages/@rescript/runtime/lib/js/Belt_internalSetInt.cjs
index cf33c6f0805..37156dd7ced 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalSetInt.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_internalSetInt.cjs
@@ -115,21 +115,6 @@ function get(_n, x) {
   };
 }
 
-function getUndefined(_n, x) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.v;
-    if (x === v) {
-      return v;
-    }
-    _n = x < v ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x) {
   while (true) {
     let n = _n;
@@ -200,7 +185,6 @@ exports.cmp = cmp;
 exports.eq = eq;
 exports.subset = subset;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getOrThrow = getOrThrow;
 exports.addMutate = addMutate;
 exports.fromArray = fromArray;
diff --git a/packages/@rescript/runtime/lib/js/Belt_internalSetString.cjs b/packages/@rescript/runtime/lib/js/Belt_internalSetString.cjs
index 76e98bdc70a..15786f83f6c 100644
--- a/packages/@rescript/runtime/lib/js/Belt_internalSetString.cjs
+++ b/packages/@rescript/runtime/lib/js/Belt_internalSetString.cjs
@@ -115,21 +115,6 @@ function get(_n, x) {
   };
 }
 
-function getUndefined(_n, x) {
-  while (true) {
-    let n = _n;
-    if (n === undefined) {
-      return;
-    }
-    let v = n.v;
-    if (x === v) {
-      return v;
-    }
-    _n = x < v ? n.l : n.r;
-    continue;
-  };
-}
-
 function getOrThrow(_n, x) {
   while (true) {
     let n = _n;
@@ -200,7 +185,6 @@ exports.cmp = cmp;
 exports.eq = eq;
 exports.subset = subset;
 exports.get = get;
-exports.getUndefined = getUndefined;
 exports.getOrThrow = getOrThrow;
 exports.addMutate = addMutate;
 exports.fromArray = fromArray;
diff --git a/tests/analysis_tests/tests-reanalyze/deadcode/expected/deadcode.txt b/tests/analysis_tests/tests-reanalyze/deadcode/expected/deadcode.txt
index 7d00a6a60fc..7ea5d1387e7 100644
--- a/tests/analysis_tests/tests-reanalyze/deadcode/expected/deadcode.txt
+++ b/tests/analysis_tests/tests-reanalyze/deadcode/expected/deadcode.txt
@@ -442,59 +442,58 @@
   addValueDeclaration +get ImmutableArray.res:24:6 path:+ImmutableArray.Array
   addValueDeclaration +getExn ImmutableArray.res:26:6 path:+ImmutableArray.Array
   addValueDeclaration +getUnsafe ImmutableArray.res:28:6 path:+ImmutableArray.Array
-  addValueDeclaration +getUndefined ImmutableArray.res:30:6 path:+ImmutableArray.Array
-  addValueDeclaration +shuffle ImmutableArray.res:32:6 path:+ImmutableArray.Array
-  addValueDeclaration +reverse ImmutableArray.res:34:6 path:+ImmutableArray.Array
-  addValueDeclaration +makeUninitialized ImmutableArray.res:36:6 path:+ImmutableArray.Array
-  addValueDeclaration +makeUninitializedUnsafe ImmutableArray.res:38:6 path:+ImmutableArray.Array
-  addValueDeclaration +make ImmutableArray.res:40:6 path:+ImmutableArray.Array
-  addValueDeclaration +range ImmutableArray.res:42:6 path:+ImmutableArray.Array
-  addValueDeclaration +rangeBy ImmutableArray.res:44:6 path:+ImmutableArray.Array
-  addValueDeclaration +makeByU ImmutableArray.res:46:6 path:+ImmutableArray.Array
-  addValueDeclaration +makeBy ImmutableArray.res:47:6 path:+ImmutableArray.Array
-  addValueDeclaration +makeByAndShuffleU ImmutableArray.res:49:6 path:+ImmutableArray.Array
-  addValueDeclaration +makeByAndShuffle ImmutableArray.res:50:6 path:+ImmutableArray.Array
-  addValueDeclaration +zip ImmutableArray.res:52:6 path:+ImmutableArray.Array
-  addValueDeclaration +zipByU ImmutableArray.res:54:6 path:+ImmutableArray.Array
-  addValueDeclaration +zipBy ImmutableArray.res:55:6 path:+ImmutableArray.Array
-  addValueDeclaration +unzip ImmutableArray.res:57:6 path:+ImmutableArray.Array
-  addValueDeclaration +concat ImmutableArray.res:59:6 path:+ImmutableArray.Array
-  addValueDeclaration +concatMany ImmutableArray.res:61:6 path:+ImmutableArray.Array
-  addValueDeclaration +slice ImmutableArray.res:63:6 path:+ImmutableArray.Array
-  addValueDeclaration +sliceToEnd ImmutableArray.res:65:6 path:+ImmutableArray.Array
-  addValueDeclaration +copy ImmutableArray.res:67:6 path:+ImmutableArray.Array
-  addValueDeclaration +forEachU ImmutableArray.res:69:6 path:+ImmutableArray.Array
-  addValueDeclaration +forEach ImmutableArray.res:70:6 path:+ImmutableArray.Array
-  addValueDeclaration +mapU ImmutableArray.res:72:6 path:+ImmutableArray.Array
-  addValueDeclaration +map ImmutableArray.res:73:6 path:+ImmutableArray.Array
-  addValueDeclaration +keepWithIndexU ImmutableArray.res:75:6 path:+ImmutableArray.Array
-  addValueDeclaration +keepWithIndex ImmutableArray.res:76:6 path:+ImmutableArray.Array
-  addValueDeclaration +keepMapU ImmutableArray.res:78:6 path:+ImmutableArray.Array
-  addValueDeclaration +keepMap ImmutableArray.res:79:6 path:+ImmutableArray.Array
-  addValueDeclaration +forEachWithIndexU ImmutableArray.res:81:6 path:+ImmutableArray.Array
-  addValueDeclaration +forEachWithIndex ImmutableArray.res:82:6 path:+ImmutableArray.Array
-  addValueDeclaration +mapWithIndexU ImmutableArray.res:84:6 path:+ImmutableArray.Array
-  addValueDeclaration +mapWithIndex ImmutableArray.res:85:6 path:+ImmutableArray.Array
-  addValueDeclaration +partitionU ImmutableArray.res:87:6 path:+ImmutableArray.Array
-  addValueDeclaration +partition ImmutableArray.res:88:6 path:+ImmutableArray.Array
-  addValueDeclaration +reduceU ImmutableArray.res:90:6 path:+ImmutableArray.Array
-  addValueDeclaration +reduce ImmutableArray.res:91:6 path:+ImmutableArray.Array
-  addValueDeclaration +reduceReverseU ImmutableArray.res:93:6 path:+ImmutableArray.Array
-  addValueDeclaration +reduceReverse ImmutableArray.res:94:6 path:+ImmutableArray.Array
-  addValueDeclaration +reduceReverse2U ImmutableArray.res:96:6 path:+ImmutableArray.Array
-  addValueDeclaration +reduceReverse2 ImmutableArray.res:97:6 path:+ImmutableArray.Array
-  addValueDeclaration +someU ImmutableArray.res:99:6 path:+ImmutableArray.Array
-  addValueDeclaration +some ImmutableArray.res:100:6 path:+ImmutableArray.Array
-  addValueDeclaration +everyU ImmutableArray.res:102:6 path:+ImmutableArray.Array
-  addValueDeclaration +every ImmutableArray.res:103:6 path:+ImmutableArray.Array
-  addValueDeclaration +every2U ImmutableArray.res:105:6 path:+ImmutableArray.Array
-  addValueDeclaration +every2 ImmutableArray.res:106:6 path:+ImmutableArray.Array
-  addValueDeclaration +some2U ImmutableArray.res:108:6 path:+ImmutableArray.Array
-  addValueDeclaration +some2 ImmutableArray.res:109:6 path:+ImmutableArray.Array
-  addValueDeclaration +cmpU ImmutableArray.res:111:6 path:+ImmutableArray.Array
-  addValueDeclaration +cmp ImmutableArray.res:112:6 path:+ImmutableArray.Array
-  addValueDeclaration +eqU ImmutableArray.res:114:6 path:+ImmutableArray.Array
-  addValueDeclaration +eq ImmutableArray.res:115:6 path:+ImmutableArray.Array
+  addValueDeclaration +shuffle ImmutableArray.res:30:6 path:+ImmutableArray.Array
+  addValueDeclaration +reverse ImmutableArray.res:32:6 path:+ImmutableArray.Array
+  addValueDeclaration +makeUninitialized ImmutableArray.res:34:6 path:+ImmutableArray.Array
+  addValueDeclaration +makeUninitializedUnsafe ImmutableArray.res:36:6 path:+ImmutableArray.Array
+  addValueDeclaration +make ImmutableArray.res:38:6 path:+ImmutableArray.Array
+  addValueDeclaration +range ImmutableArray.res:40:6 path:+ImmutableArray.Array
+  addValueDeclaration +rangeBy ImmutableArray.res:42:6 path:+ImmutableArray.Array
+  addValueDeclaration +makeByU ImmutableArray.res:44:6 path:+ImmutableArray.Array
+  addValueDeclaration +makeBy ImmutableArray.res:45:6 path:+ImmutableArray.Array
+  addValueDeclaration +makeByAndShuffleU ImmutableArray.res:47:6 path:+ImmutableArray.Array
+  addValueDeclaration +makeByAndShuffle ImmutableArray.res:48:6 path:+ImmutableArray.Array
+  addValueDeclaration +zip ImmutableArray.res:50:6 path:+ImmutableArray.Array
+  addValueDeclaration +zipByU ImmutableArray.res:52:6 path:+ImmutableArray.Array
+  addValueDeclaration +zipBy ImmutableArray.res:53:6 path:+ImmutableArray.Array
+  addValueDeclaration +unzip ImmutableArray.res:55:6 path:+ImmutableArray.Array
+  addValueDeclaration +concat ImmutableArray.res:57:6 path:+ImmutableArray.Array
+  addValueDeclaration +concatMany ImmutableArray.res:59:6 path:+ImmutableArray.Array
+  addValueDeclaration +slice ImmutableArray.res:61:6 path:+ImmutableArray.Array
+  addValueDeclaration +sliceToEnd ImmutableArray.res:63:6 path:+ImmutableArray.Array
+  addValueDeclaration +copy ImmutableArray.res:65:6 path:+ImmutableArray.Array
+  addValueDeclaration +forEachU ImmutableArray.res:67:6 path:+ImmutableArray.Array
+  addValueDeclaration +forEach ImmutableArray.res:68:6 path:+ImmutableArray.Array
+  addValueDeclaration +mapU ImmutableArray.res:70:6 path:+ImmutableArray.Array
+  addValueDeclaration +map ImmutableArray.res:71:6 path:+ImmutableArray.Array
+  addValueDeclaration +keepWithIndexU ImmutableArray.res:73:6 path:+ImmutableArray.Array
+  addValueDeclaration +keepWithIndex ImmutableArray.res:74:6 path:+ImmutableArray.Array
+  addValueDeclaration +keepMapU ImmutableArray.res:76:6 path:+ImmutableArray.Array
+  addValueDeclaration +keepMap ImmutableArray.res:77:6 path:+ImmutableArray.Array
+  addValueDeclaration +forEachWithIndexU ImmutableArray.res:79:6 path:+ImmutableArray.Array
+  addValueDeclaration +forEachWithIndex ImmutableArray.res:80:6 path:+ImmutableArray.Array
+  addValueDeclaration +mapWithIndexU ImmutableArray.res:82:6 path:+ImmutableArray.Array
+  addValueDeclaration +mapWithIndex ImmutableArray.res:83:6 path:+ImmutableArray.Array
+  addValueDeclaration +partitionU ImmutableArray.res:85:6 path:+ImmutableArray.Array
+  addValueDeclaration +partition ImmutableArray.res:86:6 path:+ImmutableArray.Array
+  addValueDeclaration +reduceU ImmutableArray.res:88:6 path:+ImmutableArray.Array
+  addValueDeclaration +reduce ImmutableArray.res:89:6 path:+ImmutableArray.Array
+  addValueDeclaration +reduceReverseU ImmutableArray.res:91:6 path:+ImmutableArray.Array
+  addValueDeclaration +reduceReverse ImmutableArray.res:92:6 path:+ImmutableArray.Array
+  addValueDeclaration +reduceReverse2U ImmutableArray.res:94:6 path:+ImmutableArray.Array
+  addValueDeclaration +reduceReverse2 ImmutableArray.res:95:6 path:+ImmutableArray.Array
+  addValueDeclaration +someU ImmutableArray.res:97:6 path:+ImmutableArray.Array
+  addValueDeclaration +some ImmutableArray.res:98:6 path:+ImmutableArray.Array
+  addValueDeclaration +everyU ImmutableArray.res:100:6 path:+ImmutableArray.Array
+  addValueDeclaration +every ImmutableArray.res:101:6 path:+ImmutableArray.Array
+  addValueDeclaration +every2U ImmutableArray.res:103:6 path:+ImmutableArray.Array
+  addValueDeclaration +every2 ImmutableArray.res:104:6 path:+ImmutableArray.Array
+  addValueDeclaration +some2U ImmutableArray.res:106:6 path:+ImmutableArray.Array
+  addValueDeclaration +some2 ImmutableArray.res:107:6 path:+ImmutableArray.Array
+  addValueDeclaration +cmpU ImmutableArray.res:109:6 path:+ImmutableArray.Array
+  addValueDeclaration +cmp ImmutableArray.res:110:6 path:+ImmutableArray.Array
+  addValueDeclaration +eqU ImmutableArray.res:112:6 path:+ImmutableArray.Array
+  addValueDeclaration +eq ImmutableArray.res:113:6 path:+ImmutableArray.Array
   addValueDeclaration +fromArray ImmutableArray.res:14:6 path:+ImmutableArray
   addValueDeclaration +toArray ImmutableArray.res:16:6 path:+ImmutableArray
   addValueDeclaration +length ImmutableArray.res:20:6 path:+ImmutableArray
@@ -502,59 +501,58 @@
   addValueDeclaration +get ImmutableArray.res:24:6 path:+ImmutableArray
   addValueDeclaration +getExn ImmutableArray.res:26:6 path:+ImmutableArray
   addValueDeclaration +getUnsafe ImmutableArray.res:28:6 path:+ImmutableArray
-  addValueDeclaration +getUndefined ImmutableArray.res:30:6 path:+ImmutableArray
-  addValueDeclaration +shuffle ImmutableArray.res:32:6 path:+ImmutableArray
-  addValueDeclaration +reverse ImmutableArray.res:34:6 path:+ImmutableArray
-  addValueDeclaration +makeUninitialized ImmutableArray.res:36:6 path:+ImmutableArray
-  addValueDeclaration +makeUninitializedUnsafe ImmutableArray.res:38:6 path:+ImmutableArray
-  addValueDeclaration +make ImmutableArray.res:40:6 path:+ImmutableArray
-  addValueDeclaration +range ImmutableArray.res:42:6 path:+ImmutableArray
-  addValueDeclaration +rangeBy ImmutableArray.res:44:6 path:+ImmutableArray
-  addValueDeclaration +makeByU ImmutableArray.res:46:6 path:+ImmutableArray
-  addValueDeclaration +makeBy ImmutableArray.res:47:6 path:+ImmutableArray
-  addValueDeclaration +makeByAndShuffleU ImmutableArray.res:49:6 path:+ImmutableArray
-  addValueDeclaration +makeByAndShuffle ImmutableArray.res:50:6 path:+ImmutableArray
-  addValueDeclaration +zip ImmutableArray.res:52:6 path:+ImmutableArray
-  addValueDeclaration +zipByU ImmutableArray.res:54:6 path:+ImmutableArray
-  addValueDeclaration +zipBy ImmutableArray.res:55:6 path:+ImmutableArray
-  addValueDeclaration +unzip ImmutableArray.res:57:6 path:+ImmutableArray
-  addValueDeclaration +concat ImmutableArray.res:59:6 path:+ImmutableArray
-  addValueDeclaration +concatMany ImmutableArray.res:61:6 path:+ImmutableArray
-  addValueDeclaration +slice ImmutableArray.res:63:6 path:+ImmutableArray
-  addValueDeclaration +sliceToEnd ImmutableArray.res:65:6 path:+ImmutableArray
-  addValueDeclaration +copy ImmutableArray.res:67:6 path:+ImmutableArray
-  addValueDeclaration +forEachU ImmutableArray.res:69:6 path:+ImmutableArray
-  addValueDeclaration +forEach ImmutableArray.res:70:6 path:+ImmutableArray
-  addValueDeclaration +mapU ImmutableArray.res:72:6 path:+ImmutableArray
-  addValueDeclaration +map ImmutableArray.res:73:6 path:+ImmutableArray
-  addValueDeclaration +keepWithIndexU ImmutableArray.res:75:6 path:+ImmutableArray
-  addValueDeclaration +keepWithIndex ImmutableArray.res:76:6 path:+ImmutableArray
-  addValueDeclaration +keepMapU ImmutableArray.res:78:6 path:+ImmutableArray
-  addValueDeclaration +keepMap ImmutableArray.res:79:6 path:+ImmutableArray
-  addValueDeclaration +forEachWithIndexU ImmutableArray.res:81:6 path:+ImmutableArray
-  addValueDeclaration +forEachWithIndex ImmutableArray.res:82:6 path:+ImmutableArray
-  addValueDeclaration +mapWithIndexU ImmutableArray.res:84:6 path:+ImmutableArray
-  addValueDeclaration +mapWithIndex ImmutableArray.res:85:6 path:+ImmutableArray
-  addValueDeclaration +partitionU ImmutableArray.res:87:6 path:+ImmutableArray
-  addValueDeclaration +partition ImmutableArray.res:88:6 path:+ImmutableArray
-  addValueDeclaration +reduceU ImmutableArray.res:90:6 path:+ImmutableArray
-  addValueDeclaration +reduce ImmutableArray.res:91:6 path:+ImmutableArray
-  addValueDeclaration +reduceReverseU ImmutableArray.res:93:6 path:+ImmutableArray
-  addValueDeclaration +reduceReverse ImmutableArray.res:94:6 path:+ImmutableArray
-  addValueDeclaration +reduceReverse2U ImmutableArray.res:96:6 path:+ImmutableArray
-  addValueDeclaration +reduceReverse2 ImmutableArray.res:97:6 path:+ImmutableArray
-  addValueDeclaration +someU ImmutableArray.res:99:6 path:+ImmutableArray
-  addValueDeclaration +some ImmutableArray.res:100:6 path:+ImmutableArray
-  addValueDeclaration +everyU ImmutableArray.res:102:6 path:+ImmutableArray
-  addValueDeclaration +every ImmutableArray.res:103:6 path:+ImmutableArray
-  addValueDeclaration +every2U ImmutableArray.res:105:6 path:+ImmutableArray
-  addValueDeclaration +every2 ImmutableArray.res:106:6 path:+ImmutableArray
-  addValueDeclaration +some2U ImmutableArray.res:108:6 path:+ImmutableArray
-  addValueDeclaration +some2 ImmutableArray.res:109:6 path:+ImmutableArray
-  addValueDeclaration +cmpU ImmutableArray.res:111:6 path:+ImmutableArray
-  addValueDeclaration +cmp ImmutableArray.res:112:6 path:+ImmutableArray
-  addValueDeclaration +eqU ImmutableArray.res:114:6 path:+ImmutableArray
-  addValueDeclaration +eq ImmutableArray.res:115:6 path:+ImmutableArray
+  addValueDeclaration +shuffle ImmutableArray.res:30:6 path:+ImmutableArray
+  addValueDeclaration +reverse ImmutableArray.res:32:6 path:+ImmutableArray
+  addValueDeclaration +makeUninitialized ImmutableArray.res:34:6 path:+ImmutableArray
+  addValueDeclaration +makeUninitializedUnsafe ImmutableArray.res:36:6 path:+ImmutableArray
+  addValueDeclaration +make ImmutableArray.res:38:6 path:+ImmutableArray
+  addValueDeclaration +range ImmutableArray.res:40:6 path:+ImmutableArray
+  addValueDeclaration +rangeBy ImmutableArray.res:42:6 path:+ImmutableArray
+  addValueDeclaration +makeByU ImmutableArray.res:44:6 path:+ImmutableArray
+  addValueDeclaration +makeBy ImmutableArray.res:45:6 path:+ImmutableArray
+  addValueDeclaration +makeByAndShuffleU ImmutableArray.res:47:6 path:+ImmutableArray
+  addValueDeclaration +makeByAndShuffle ImmutableArray.res:48:6 path:+ImmutableArray
+  addValueDeclaration +zip ImmutableArray.res:50:6 path:+ImmutableArray
+  addValueDeclaration +zipByU ImmutableArray.res:52:6 path:+ImmutableArray
+  addValueDeclaration +zipBy ImmutableArray.res:53:6 path:+ImmutableArray
+  addValueDeclaration +unzip ImmutableArray.res:55:6 path:+ImmutableArray
+  addValueDeclaration +concat ImmutableArray.res:57:6 path:+ImmutableArray
+  addValueDeclaration +concatMany ImmutableArray.res:59:6 path:+ImmutableArray
+  addValueDeclaration +slice ImmutableArray.res:61:6 path:+ImmutableArray
+  addValueDeclaration +sliceToEnd ImmutableArray.res:63:6 path:+ImmutableArray
+  addValueDeclaration +copy ImmutableArray.res:65:6 path:+ImmutableArray
+  addValueDeclaration +forEachU ImmutableArray.res:67:6 path:+ImmutableArray
+  addValueDeclaration +forEach ImmutableArray.res:68:6 path:+ImmutableArray
+  addValueDeclaration +mapU ImmutableArray.res:70:6 path:+ImmutableArray
+  addValueDeclaration +map ImmutableArray.res:71:6 path:+ImmutableArray
+  addValueDeclaration +keepWithIndexU ImmutableArray.res:73:6 path:+ImmutableArray
+  addValueDeclaration +keepWithIndex ImmutableArray.res:74:6 path:+ImmutableArray
+  addValueDeclaration +keepMapU ImmutableArray.res:76:6 path:+ImmutableArray
+  addValueDeclaration +keepMap ImmutableArray.res:77:6 path:+ImmutableArray
+  addValueDeclaration +forEachWithIndexU ImmutableArray.res:79:6 path:+ImmutableArray
+  addValueDeclaration +forEachWithIndex ImmutableArray.res:80:6 path:+ImmutableArray
+  addValueDeclaration +mapWithIndexU ImmutableArray.res:82:6 path:+ImmutableArray
+  addValueDeclaration +mapWithIndex ImmutableArray.res:83:6 path:+ImmutableArray
+  addValueDeclaration +partitionU ImmutableArray.res:85:6 path:+ImmutableArray
+  addValueDeclaration +partition ImmutableArray.res:86:6 path:+ImmutableArray
+  addValueDeclaration +reduceU ImmutableArray.res:88:6 path:+ImmutableArray
+  addValueDeclaration +reduce ImmutableArray.res:89:6 path:+ImmutableArray
+  addValueDeclaration +reduceReverseU ImmutableArray.res:91:6 path:+ImmutableArray
+  addValueDeclaration +reduceReverse ImmutableArray.res:92:6 path:+ImmutableArray
+  addValueDeclaration +reduceReverse2U ImmutableArray.res:94:6 path:+ImmutableArray
+  addValueDeclaration +reduceReverse2 ImmutableArray.res:95:6 path:+ImmutableArray
+  addValueDeclaration +someU ImmutableArray.res:97:6 path:+ImmutableArray
+  addValueDeclaration +some ImmutableArray.res:98:6 path:+ImmutableArray
+  addValueDeclaration +everyU ImmutableArray.res:100:6 path:+ImmutableArray
+  addValueDeclaration +every ImmutableArray.res:101:6 path:+ImmutableArray
+  addValueDeclaration +every2U ImmutableArray.res:103:6 path:+ImmutableArray
+  addValueDeclaration +every2 ImmutableArray.res:104:6 path:+ImmutableArray
+  addValueDeclaration +some2U ImmutableArray.res:106:6 path:+ImmutableArray
+  addValueDeclaration +some2 ImmutableArray.res:107:6 path:+ImmutableArray
+  addValueDeclaration +cmpU ImmutableArray.res:109:6 path:+ImmutableArray
+  addValueDeclaration +cmp ImmutableArray.res:110:6 path:+ImmutableArray
+  addValueDeclaration +eqU ImmutableArray.res:112:6 path:+ImmutableArray
+  addValueDeclaration +eq ImmutableArray.res:113:6 path:+ImmutableArray
   addValueReference ImmutableArray.res:14:6 --> ImmutableArray.res:14:18
   addValueReference ImmutableArray.res:14:6 --> ImmutableArray.res:8:2
   addValueReference ImmutableArray.res:16:6 --> ImmutableArray.res:16:16
@@ -572,213 +570,210 @@
   addValueReference ImmutableArray.res:28:6 --> ImmutableArray.res:28:19
   addValueReference ImmutableArray.res:28:6 --> ImmutableArray.res:5:2
   addValueReference ImmutableArray.res:28:6 --> ImmutableArray.res:28:22
-  addValueReference ImmutableArray.res:30:6 --> ImmutableArray.res:30:22
+  addValueReference ImmutableArray.res:30:6 --> ImmutableArray.res:30:16
   addValueReference ImmutableArray.res:30:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:30:6 --> ImmutableArray.res:30:25
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   addValueReference ImmutableArray.res:32:6 --> ImmutableArray.res:32:16
   addValueReference ImmutableArray.res:32:6 --> ImmutableArray.res:5:2
   addValueReference ImmutableArray.res:32:6 --> ImmutableArray.res:8:2
-  addValueReference ImmutableArray.res:34:6 --> ImmutableArray.res:34:16
-  addValueReference ImmutableArray.res:34:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:34:6 --> ImmutableArray.res:8:2
-  addValueReference ImmutableArray.res:36:6 --> ImmutableArray.res:36:26
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   addValueReference ImmutableArray.res:36:6 --> ImmutableArray.res:8:2
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   addValueReference ImmutableArray.res:38:6 --> ImmutableArray.res:8:2
-  addValueReference ImmutableArray.res:40:6 --> ImmutableArray.res:40:14
-  addValueReference ImmutableArray.res:40:6 --> ImmutableArray.res:40:17
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   addValueReference ImmutableArray.res:40:6 --> ImmutableArray.res:8:2
-  addValueReference ImmutableArray.res:42:6 --> ImmutableArray.res:42:15
-  addValueReference ImmutableArray.res:42:6 --> ImmutableArray.res:42:18
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   addValueReference ImmutableArray.res:42:6 --> ImmutableArray.res:8:2
   addValueReference ImmutableArray.res:44:6 --> ImmutableArray.res:44:17
   addValueReference ImmutableArray.res:44:6 --> ImmutableArray.res:44:20
-  addValueReference ImmutableArray.res:44:6 --> ImmutableArray.res:44:23
   addValueReference ImmutableArray.res:44:6 --> ImmutableArray.res:8:2
-  addValueReference ImmutableArray.res:46:6 --> ImmutableArray.res:46:17
-  addValueReference ImmutableArray.res:46:6 --> ImmutableArray.res:46:20
-  addValueReference ImmutableArray.res:46:6 --> ImmutableArray.res:8:2
-  addValueReference ImmutableArray.res:47:6 --> ImmutableArray.res:47:16
-  addValueReference ImmutableArray.res:47:6 --> ImmutableArray.res:47:19
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   addValueReference ImmutableArray.res:47:6 --> ImmutableArray.res:8:2
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-  addValueReference ImmutableArray.res:49:6 --> ImmutableArray.res:49:30
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-  addValueReference ImmutableArray.res:50:6 --> ImmutableArray.res:50:29
-  addValueReference ImmutableArray.res:50:6 --> ImmutableArray.res:8:2
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   addValueReference ImmutableArray.res:52:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:52:6 --> ImmutableArray.res:52:17
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   addValueReference ImmutableArray.res:52:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:52:6 --> ImmutableArray.res:9:2
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-  addValueReference ImmutableArray.res:54:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:54:6 --> ImmutableArray.res:54:20
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-  addValueReference ImmutableArray.res:54:6 --> ImmutableArray.res:54:24
-  addValueReference ImmutableArray.res:54:6 --> ImmutableArray.res:8:2
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-  addValueReference ImmutableArray.res:55:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:55:6 --> ImmutableArray.res:55:19
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-  addValueReference ImmutableArray.res:55:6 --> ImmutableArray.res:55:23
-  addValueReference ImmutableArray.res:55:6 --> ImmutableArray.res:8:2
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-  addValueReference ImmutableArray.res:57:6 --> ImmutableArray.res:6:2
-  addValueReference ImmutableArray.res:57:6 --> ImmutableArray.res:10:2
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-  addValueReference ImmutableArray.res:59:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:59:6 --> ImmutableArray.res:59:20
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   addValueReference ImmutableArray.res:59:6 --> ImmutableArray.res:8:2
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   addValueReference ImmutableArray.res:61:6 --> ImmutableArray.res:8:2
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   addValueReference ImmutableArray.res:63:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:63:6 --> ImmutableArray.res:63:18
-  addValueReference ImmutableArray.res:63:6 --> ImmutableArray.res:63:27
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   addValueReference ImmutableArray.res:63:6 --> ImmutableArray.res:8:2
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   addValueReference ImmutableArray.res:65:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:65:6 --> ImmutableArray.res:65:23
   addValueReference ImmutableArray.res:65:6 --> ImmutableArray.res:8:2
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   addValueReference ImmutableArray.res:67:6 --> ImmutableArray.res:5:2
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-  addValueReference ImmutableArray.res:69:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:69:6 --> ImmutableArray.res:69:21
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   addValueReference ImmutableArray.res:70:6 --> ImmutableArray.res:5:2
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-  addValueReference ImmutableArray.res:72:6 --> ImmutableArray.res:72:17
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   addValueReference ImmutableArray.res:73:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:73:6 --> ImmutableArray.res:8:2
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   addValueReference ImmutableArray.res:76:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:76:6 --> ImmutableArray.res:8:2
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   addValueReference ImmutableArray.res:79:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:82:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:85:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:88:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:91:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:94:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:94:6 --> ImmutableArray.res:94:29
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   addValueReference ImmutableArray.res:97:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:100:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:103:6 --> ImmutableArray.res:5:2
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   addValueReference ImmutableArray.res:106:6 --> ImmutableArray.res:106:16
   addValueReference ImmutableArray.res:106:6 --> ImmutableArray.res:5:2
   addValueReference ImmutableArray.res:106:6 --> ImmutableArray.res:106:20
   addValueReference ImmutableArray.res:106:6 --> ImmutableArray.res:5:2
   addValueReference ImmutableArray.res:106:6 --> ImmutableArray.res:106:24
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-  addValueReference ImmutableArray.res:108:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:108:6 --> ImmutableArray.res:108:24
-  addValueReference ImmutableArray.res:109:6 --> ImmutableArray.res:109:15
+  addValueReference ImmutableArray.res:107:6 --> ImmutableArray.res:107:15
+  addValueReference ImmutableArray.res:107:6 --> ImmutableArray.res:5:2
+  addValueReference ImmutableArray.res:107:6 --> ImmutableArray.res:107:19
+  addValueReference ImmutableArray.res:107:6 --> ImmutableArray.res:5:2
+  addValueReference ImmutableArray.res:107:6 --> ImmutableArray.res:107:23
+  addValueReference ImmutableArray.res:109:6 --> ImmutableArray.res:109:14
   addValueReference ImmutableArray.res:109:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:109:6 --> ImmutableArray.res:109:19
+  addValueReference ImmutableArray.res:109:6 --> ImmutableArray.res:109:18
   addValueReference ImmutableArray.res:109:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:109:6 --> ImmutableArray.res:109:23
-  addValueReference ImmutableArray.res:111:6 --> ImmutableArray.res:111:14
-  addValueReference ImmutableArray.res:111:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:111:6 --> ImmutableArray.res:111:18
-  addValueReference ImmutableArray.res:111:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:111:6 --> ImmutableArray.res:111:22
+  addValueReference ImmutableArray.res:109:6 --> ImmutableArray.res:109:22
+  addValueReference ImmutableArray.res:110:6 --> ImmutableArray.res:110:13
+  addValueReference ImmutableArray.res:110:6 --> ImmutableArray.res:5:2
+  addValueReference ImmutableArray.res:110:6 --> ImmutableArray.res:110:17
+  addValueReference ImmutableArray.res:110:6 --> ImmutableArray.res:5:2
+  addValueReference ImmutableArray.res:110:6 --> ImmutableArray.res:110:21
   addValueReference ImmutableArray.res:112:6 --> ImmutableArray.res:112:13
   addValueReference ImmutableArray.res:112:6 --> ImmutableArray.res:5:2
   addValueReference ImmutableArray.res:112:6 --> ImmutableArray.res:112:17
   addValueReference ImmutableArray.res:112:6 --> ImmutableArray.res:5:2
   addValueReference ImmutableArray.res:112:6 --> ImmutableArray.res:112:21
-  addValueReference ImmutableArray.res:114:6 --> ImmutableArray.res:114:13
-  addValueReference ImmutableArray.res:114:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:114:6 --> ImmutableArray.res:114:17
-  addValueReference ImmutableArray.res:114:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:114:6 --> ImmutableArray.res:114:21
-  addValueReference ImmutableArray.res:115:6 --> ImmutableArray.res:115:12
-  addValueReference ImmutableArray.res:115:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:115:6 --> ImmutableArray.res:115:16
-  addValueReference ImmutableArray.res:115:6 --> ImmutableArray.res:5:2
-  addValueReference ImmutableArray.res:115:6 --> ImmutableArray.res:115:20
+  addValueReference ImmutableArray.res:113:6 --> ImmutableArray.res:113:12
+  addValueReference ImmutableArray.res:113:6 --> ImmutableArray.res:5:2
+  addValueReference ImmutableArray.res:113:6 --> ImmutableArray.res:113:16
+  addValueReference ImmutableArray.res:113:6 --> ImmutableArray.res:5:2
+  addValueReference ImmutableArray.res:113:6 --> ImmutableArray.res:113:20
   addValueReference ImmutableArray.resi:6:2 --> ImmutableArray.res:24:6
   addValueReference ImmutableArray.resi:9:0 --> ImmutableArray.res:14:6
   addValueReference ImmutableArray.resi:12:0 --> ImmutableArray.res:16:6
@@ -795,12 +790,12 @@
   addValueReference ImmutableArray.resi:35:0 --> ImmutableArray.res:40:6
   addValueReference ImmutableArray.resi:37:0 --> ImmutableArray.res:42:6
   addValueReference ImmutableArray.resi:39:0 --> ImmutableArray.res:44:6
-  addValueReference ImmutableArray.resi:41:0 --> ImmutableArray.res:46:6
+  addValueReference ImmutableArray.resi:40:0 --> ImmutableArray.res:45:6
   addValueReference ImmutableArray.resi:42:0 --> ImmutableArray.res:47:6
-  addValueReference ImmutableArray.resi:44:0 --> ImmutableArray.res:49:6
+  addValueReference ImmutableArray.resi:43:0 --> ImmutableArray.res:48:6
   addValueReference ImmutableArray.resi:45:0 --> ImmutableArray.res:50:6
   addValueReference ImmutableArray.resi:47:0 --> ImmutableArray.res:52:6
-  addValueReference ImmutableArray.resi:49:0 --> ImmutableArray.res:54:6
+  addValueReference ImmutableArray.resi:48:0 --> ImmutableArray.res:53:6
   addValueReference ImmutableArray.resi:50:0 --> ImmutableArray.res:55:6
   addValueReference ImmutableArray.resi:52:0 --> ImmutableArray.res:57:6
   addValueReference ImmutableArray.resi:54:0 --> ImmutableArray.res:59:6
@@ -808,38 +803,37 @@
   addValueReference ImmutableArray.resi:58:0 --> ImmutableArray.res:63:6
   addValueReference ImmutableArray.resi:60:0 --> ImmutableArray.res:65:6
   addValueReference ImmutableArray.resi:62:0 --> ImmutableArray.res:67:6
-  addValueReference ImmutableArray.resi:64:0 --> ImmutableArray.res:69:6
+  addValueReference ImmutableArray.resi:63:0 --> ImmutableArray.res:68:6
   addValueReference ImmutableArray.resi:65:0 --> ImmutableArray.res:70:6
-  addValueReference ImmutableArray.resi:67:0 --> ImmutableArray.res:72:6
+  addValueReference ImmutableArray.resi:66:0 --> ImmutableArray.res:71:6
   addValueReference ImmutableArray.resi:68:0 --> ImmutableArray.res:73:6
-  addValueReference ImmutableArray.resi:70:0 --> ImmutableArray.res:75:6
+  addValueReference ImmutableArray.resi:69:0 --> ImmutableArray.res:74:6
   addValueReference ImmutableArray.resi:71:0 --> ImmutableArray.res:76:6
-  addValueReference ImmutableArray.resi:73:0 --> ImmutableArray.res:78:6
+  addValueReference ImmutableArray.resi:72:0 --> ImmutableArray.res:77:6
   addValueReference ImmutableArray.resi:74:0 --> ImmutableArray.res:79:6
-  addValueReference ImmutableArray.resi:76:0 --> ImmutableArray.res:81:6
+  addValueReference ImmutableArray.resi:75:0 --> ImmutableArray.res:80:6
   addValueReference ImmutableArray.resi:77:0 --> ImmutableArray.res:82:6
-  addValueReference ImmutableArray.resi:79:0 --> ImmutableArray.res:84:6
+  addValueReference ImmutableArray.resi:78:0 --> ImmutableArray.res:83:6
   addValueReference ImmutableArray.resi:80:0 --> ImmutableArray.res:85:6
-  addValueReference ImmutableArray.resi:82:0 --> ImmutableArray.res:87:6
+  addValueReference ImmutableArray.resi:81:0 --> ImmutableArray.res:86:6
   addValueReference ImmutableArray.resi:83:0 --> ImmutableArray.res:88:6
-  addValueReference ImmutableArray.resi:85:0 --> ImmutableArray.res:90:6
+  addValueReference ImmutableArray.resi:84:0 --> ImmutableArray.res:89:6
   addValueReference ImmutableArray.resi:86:0 --> ImmutableArray.res:91:6
-  addValueReference ImmutableArray.resi:88:0 --> ImmutableArray.res:93:6
+  addValueReference ImmutableArray.resi:87:0 --> ImmutableArray.res:92:6
   addValueReference ImmutableArray.resi:89:0 --> ImmutableArray.res:94:6
-  addValueReference ImmutableArray.resi:91:0 --> ImmutableArray.res:96:6
+  addValueReference ImmutableArray.resi:90:0 --> ImmutableArray.res:95:6
   addValueReference ImmutableArray.resi:92:0 --> ImmutableArray.res:97:6
-  addValueReference ImmutableArray.resi:94:0 --> ImmutableArray.res:99:6
+  addValueReference ImmutableArray.resi:93:0 --> ImmutableArray.res:98:6
   addValueReference ImmutableArray.resi:95:0 --> ImmutableArray.res:100:6
-  addValueReference ImmutableArray.resi:97:0 --> ImmutableArray.res:102:6
+  addValueReference ImmutableArray.resi:96:0 --> ImmutableArray.res:101:6
   addValueReference ImmutableArray.resi:98:0 --> ImmutableArray.res:103:6
-  addValueReference ImmutableArray.resi:100:0 --> ImmutableArray.res:105:6
+  addValueReference ImmutableArray.resi:99:0 --> ImmutableArray.res:104:6
   addValueReference ImmutableArray.resi:101:0 --> ImmutableArray.res:106:6
-  addValueReference ImmutableArray.resi:103:0 --> ImmutableArray.res:108:6
+  addValueReference ImmutableArray.resi:102:0 --> ImmutableArray.res:107:6
   addValueReference ImmutableArray.resi:104:0 --> ImmutableArray.res:109:6
-  addValueReference ImmutableArray.resi:106:0 --> ImmutableArray.res:111:6
+  addValueReference ImmutableArray.resi:105:0 --> ImmutableArray.res:110:6
   addValueReference ImmutableArray.resi:107:0 --> ImmutableArray.res:112:6
-  addValueReference ImmutableArray.resi:109:0 --> ImmutableArray.res:114:6
-  addValueReference ImmutableArray.resi:110:0 --> ImmutableArray.res:115:6
+  addValueReference ImmutableArray.resi:108:0 --> ImmutableArray.res:113:6
   Scanning ImmutableArray.cmti Source:ImmutableArray.resi
   addValueDeclaration +get ImmutableArray.resi:6:2 path:ImmutableArray.Array
   addValueDeclaration +fromArray ImmutableArray.resi:9:0 path:ImmutableArray
@@ -849,59 +843,58 @@
   addValueDeclaration +get ImmutableArray.resi:19:0 path:ImmutableArray
   addValueDeclaration +getExn ImmutableArray.resi:21:0 path:ImmutableArray
   addValueDeclaration +getUnsafe ImmutableArray.resi:23:0 path:ImmutableArray
-  addValueDeclaration +getUndefined ImmutableArray.resi:25:0 path:ImmutableArray
-  addValueDeclaration +shuffle ImmutableArray.resi:27:0 path:ImmutableArray
-  addValueDeclaration +reverse ImmutableArray.resi:29:0 path:ImmutableArray
-  addValueDeclaration +makeUninitialized ImmutableArray.resi:31:0 path:ImmutableArray
-  addValueDeclaration +makeUninitializedUnsafe ImmutableArray.resi:33:0 path:ImmutableArray
-  addValueDeclaration +make ImmutableArray.resi:35:0 path:ImmutableArray
-  addValueDeclaration +range ImmutableArray.resi:37:0 path:ImmutableArray
-  addValueDeclaration +rangeBy ImmutableArray.resi:39:0 path:ImmutableArray
-  addValueDeclaration +makeByU ImmutableArray.resi:41:0 path:ImmutableArray
-  addValueDeclaration +makeBy ImmutableArray.resi:42:0 path:ImmutableArray
-  addValueDeclaration +makeByAndShuffleU ImmutableArray.resi:44:0 path:ImmutableArray
-  addValueDeclaration +makeByAndShuffle ImmutableArray.resi:45:0 path:ImmutableArray
-  addValueDeclaration +zip ImmutableArray.resi:47:0 path:ImmutableArray
-  addValueDeclaration +zipByU ImmutableArray.resi:49:0 path:ImmutableArray
-  addValueDeclaration +zipBy ImmutableArray.resi:50:0 path:ImmutableArray
-  addValueDeclaration +unzip ImmutableArray.resi:52:0 path:ImmutableArray
-  addValueDeclaration +concat ImmutableArray.resi:54:0 path:ImmutableArray
-  addValueDeclaration +concatMany ImmutableArray.resi:56:0 path:ImmutableArray
-  addValueDeclaration +slice ImmutableArray.resi:58:0 path:ImmutableArray
-  addValueDeclaration +sliceToEnd ImmutableArray.resi:60:0 path:ImmutableArray
-  addValueDeclaration +copy ImmutableArray.resi:62:0 path:ImmutableArray
-  addValueDeclaration +forEachU ImmutableArray.resi:64:0 path:ImmutableArray
-  addValueDeclaration +forEach ImmutableArray.resi:65:0 path:ImmutableArray
-  addValueDeclaration +mapU ImmutableArray.resi:67:0 path:ImmutableArray
-  addValueDeclaration +map ImmutableArray.resi:68:0 path:ImmutableArray
-  addValueDeclaration +keepWithIndexU ImmutableArray.resi:70:0 path:ImmutableArray
-  addValueDeclaration +keepWithIndex ImmutableArray.resi:71:0 path:ImmutableArray
-  addValueDeclaration +keepMapU ImmutableArray.resi:73:0 path:ImmutableArray
-  addValueDeclaration +keepMap ImmutableArray.resi:74:0 path:ImmutableArray
-  addValueDeclaration +forEachWithIndexU ImmutableArray.resi:76:0 path:ImmutableArray
-  addValueDeclaration +forEachWithIndex ImmutableArray.resi:77:0 path:ImmutableArray
-  addValueDeclaration +mapWithIndexU ImmutableArray.resi:79:0 path:ImmutableArray
-  addValueDeclaration +mapWithIndex ImmutableArray.resi:80:0 path:ImmutableArray
-  addValueDeclaration +partitionU ImmutableArray.resi:82:0 path:ImmutableArray
-  addValueDeclaration +partition ImmutableArray.resi:83:0 path:ImmutableArray
-  addValueDeclaration +reduceU ImmutableArray.resi:85:0 path:ImmutableArray
-  addValueDeclaration +reduce ImmutableArray.resi:86:0 path:ImmutableArray
-  addValueDeclaration +reduceReverseU ImmutableArray.resi:88:0 path:ImmutableArray
-  addValueDeclaration +reduceReverse ImmutableArray.resi:89:0 path:ImmutableArray
-  addValueDeclaration +reduceReverse2U ImmutableArray.resi:91:0 path:ImmutableArray
-  addValueDeclaration +reduceReverse2 ImmutableArray.resi:92:0 path:ImmutableArray
-  addValueDeclaration +someU ImmutableArray.resi:94:0 path:ImmutableArray
-  addValueDeclaration +some ImmutableArray.resi:95:0 path:ImmutableArray
-  addValueDeclaration +everyU ImmutableArray.resi:97:0 path:ImmutableArray
-  addValueDeclaration +every ImmutableArray.resi:98:0 path:ImmutableArray
-  addValueDeclaration +every2U ImmutableArray.resi:100:0 path:ImmutableArray
-  addValueDeclaration +every2 ImmutableArray.resi:101:0 path:ImmutableArray
-  addValueDeclaration +some2U ImmutableArray.resi:103:0 path:ImmutableArray
-  addValueDeclaration +some2 ImmutableArray.resi:104:0 path:ImmutableArray
-  addValueDeclaration +cmpU ImmutableArray.resi:106:0 path:ImmutableArray
-  addValueDeclaration +cmp ImmutableArray.resi:107:0 path:ImmutableArray
-  addValueDeclaration +eqU ImmutableArray.resi:109:0 path:ImmutableArray
-  addValueDeclaration +eq ImmutableArray.resi:110:0 path:ImmutableArray
+  addValueDeclaration +shuffle ImmutableArray.resi:25:0 path:ImmutableArray
+  addValueDeclaration +reverse ImmutableArray.resi:27:0 path:ImmutableArray
+  addValueDeclaration +makeUninitialized ImmutableArray.resi:29:0 path:ImmutableArray
+  addValueDeclaration +makeUninitializedUnsafe ImmutableArray.resi:31:0 path:ImmutableArray
+  addValueDeclaration +make ImmutableArray.resi:33:0 path:ImmutableArray
+  addValueDeclaration +range ImmutableArray.resi:35:0 path:ImmutableArray
+  addValueDeclaration +rangeBy ImmutableArray.resi:37:0 path:ImmutableArray
+  addValueDeclaration +makeByU ImmutableArray.resi:39:0 path:ImmutableArray
+  addValueDeclaration +makeBy ImmutableArray.resi:40:0 path:ImmutableArray
+  addValueDeclaration +makeByAndShuffleU ImmutableArray.resi:42:0 path:ImmutableArray
+  addValueDeclaration +makeByAndShuffle ImmutableArray.resi:43:0 path:ImmutableArray
+  addValueDeclaration +zip ImmutableArray.resi:45:0 path:ImmutableArray
+  addValueDeclaration +zipByU ImmutableArray.resi:47:0 path:ImmutableArray
+  addValueDeclaration +zipBy ImmutableArray.resi:48:0 path:ImmutableArray
+  addValueDeclaration +unzip ImmutableArray.resi:50:0 path:ImmutableArray
+  addValueDeclaration +concat ImmutableArray.resi:52:0 path:ImmutableArray
+  addValueDeclaration +concatMany ImmutableArray.resi:54:0 path:ImmutableArray
+  addValueDeclaration +slice ImmutableArray.resi:56:0 path:ImmutableArray
+  addValueDeclaration +sliceToEnd ImmutableArray.resi:58:0 path:ImmutableArray
+  addValueDeclaration +copy ImmutableArray.resi:60:0 path:ImmutableArray
+  addValueDeclaration +forEachU ImmutableArray.resi:62:0 path:ImmutableArray
+  addValueDeclaration +forEach ImmutableArray.resi:63:0 path:ImmutableArray
+  addValueDeclaration +mapU ImmutableArray.resi:65:0 path:ImmutableArray
+  addValueDeclaration +map ImmutableArray.resi:66:0 path:ImmutableArray
+  addValueDeclaration +keepWithIndexU ImmutableArray.resi:68:0 path:ImmutableArray
+  addValueDeclaration +keepWithIndex ImmutableArray.resi:69:0 path:ImmutableArray
+  addValueDeclaration +keepMapU ImmutableArray.resi:71:0 path:ImmutableArray
+  addValueDeclaration +keepMap ImmutableArray.resi:72:0 path:ImmutableArray
+  addValueDeclaration +forEachWithIndexU ImmutableArray.resi:74:0 path:ImmutableArray
+  addValueDeclaration +forEachWithIndex ImmutableArray.resi:75:0 path:ImmutableArray
+  addValueDeclaration +mapWithIndexU ImmutableArray.resi:77:0 path:ImmutableArray
+  addValueDeclaration +mapWithIndex ImmutableArray.resi:78:0 path:ImmutableArray
+  addValueDeclaration +partitionU ImmutableArray.resi:80:0 path:ImmutableArray
+  addValueDeclaration +partition ImmutableArray.resi:81:0 path:ImmutableArray
+  addValueDeclaration +reduceU ImmutableArray.resi:83:0 path:ImmutableArray
+  addValueDeclaration +reduce ImmutableArray.resi:84:0 path:ImmutableArray
+  addValueDeclaration +reduceReverseU ImmutableArray.resi:86:0 path:ImmutableArray
+  addValueDeclaration +reduceReverse ImmutableArray.resi:87:0 path:ImmutableArray
+  addValueDeclaration +reduceReverse2U ImmutableArray.resi:89:0 path:ImmutableArray
+  addValueDeclaration +reduceReverse2 ImmutableArray.resi:90:0 path:ImmutableArray
+  addValueDeclaration +someU ImmutableArray.resi:92:0 path:ImmutableArray
+  addValueDeclaration +some ImmutableArray.resi:93:0 path:ImmutableArray
+  addValueDeclaration +everyU ImmutableArray.resi:95:0 path:ImmutableArray
+  addValueDeclaration +every ImmutableArray.resi:96:0 path:ImmutableArray
+  addValueDeclaration +every2U ImmutableArray.resi:98:0 path:ImmutableArray
+  addValueDeclaration +every2 ImmutableArray.resi:99:0 path:ImmutableArray
+  addValueDeclaration +some2U ImmutableArray.resi:101:0 path:ImmutableArray
+  addValueDeclaration +some2 ImmutableArray.resi:102:0 path:ImmutableArray
+  addValueDeclaration +cmpU ImmutableArray.resi:104:0 path:ImmutableArray
+  addValueDeclaration +cmp ImmutableArray.resi:105:0 path:ImmutableArray
+  addValueDeclaration +eqU ImmutableArray.resi:107:0 path:ImmutableArray
+  addValueDeclaration +eq ImmutableArray.resi:108:0 path:ImmutableArray
   Scanning ImportHookDefault.cmt Source:ImportHookDefault.res
   addValueDeclaration +make ImportHookDefault.res:6:0 path:+ImportHookDefault
   addRecordLabelDeclaration name ImportHookDefault.res:2:2 path:+ImportHookDefault.person
@@ -1944,9 +1937,9 @@
   
 Forward Liveness Analysis
 
-    decls: 700
+    decls: 698
     roots(external targets): 134
-    decl-deps: decls_with_out=411 edges_to_decls=288
+    decl-deps: decls_with_out=409 edges_to_decls=287
 
     Root (annotated): Value +Hooks.+default
     Root (external ref): Value +FirstClassModules.M.InnerModule2.+k
@@ -2824,9 +2817,6 @@ Forward Liveness Analysis
   Dead Value +ImmutableArray.+getUnsafe
       deps: in=1 (live=0 dead=1) out=0
         <- ImmutableArray.+getUnsafe (dead)
-  Dead Value +ImmutableArray.+getUndefined
-      deps: in=1 (live=0 dead=1) out=0
-        <- ImmutableArray.+getUndefined (dead)
   Dead Value +ImmutableArray.+shuffle
       deps: in=1 (live=0 dead=1) out=0
         <- ImmutableArray.+shuffle (dead)
@@ -3008,9 +2998,6 @@ Forward Liveness Analysis
   Dead Value ImmutableArray.+getUnsafe
       deps: in=0 (live=0 dead=0) out=1
         -> +ImmutableArray.+getUnsafe
-  Dead Value ImmutableArray.+getUndefined
-      deps: in=0 (live=0 dead=0) out=1
-        -> +ImmutableArray.+getUndefined
   Dead Value ImmutableArray.+shuffle
       deps: in=0 (live=0 dead=0) out=1
         -> +ImmutableArray.+shuffle
@@ -4276,215 +4263,211 @@ Forward Liveness Analysis
   getUnsafe is never used
 
   Warning Dead Value
-  ImmutableArray.res:30:3-62
-  getUndefined is never used
-
-  Warning Dead Value
-  ImmutableArray.res:32:3-49
+  ImmutableArray.res:30:3-49
   shuffle is never used
 
   Warning Dead Value
-  ImmutableArray.res:34:3-49
+  ImmutableArray.res:32:3-49
   reverse is never used
 
   Warning Dead Value
-  ImmutableArray.res:36:3-62
+  ImmutableArray.res:34:3-62
   makeUninitialized is never used
 
   Warning Dead Value
-  ImmutableArray.res:38:3-74
+  ImmutableArray.res:36:3-74
   makeUninitializedUnsafe is never used
 
   Warning Dead Value
-  ImmutableArray.res:40:3-44
+  ImmutableArray.res:38:3-44
   make is never used
 
   Warning Dead Value
-  ImmutableArray.res:42:3-46
+  ImmutableArray.res:40:3-46
   range is never used
 
   Warning Dead Value
-  ImmutableArray.res:44:3-64
+  ImmutableArray.res:42:3-64
   rangeBy is never used
 
   Warning Dead Value
-  ImmutableArray.res:46:3-50
+  ImmutableArray.res:44:3-50
   makeByU is never used
 
   Warning Dead Value
-  ImmutableArray.res:47:3-48
+  ImmutableArray.res:45:3-48
   makeBy is never used
 
   Warning Dead Value
-  ImmutableArray.res:49:3-70
+  ImmutableArray.res:47:3-70
   makeByAndShuffleU is never used
 
   Warning Dead Value
-  ImmutableArray.res:50:3-68
+  ImmutableArray.res:48:3-68
   makeByAndShuffle is never used
 
   Warning Dead Value
-  ImmutableArray.res:52:3-61
+  ImmutableArray.res:50:3-61
   zip is never used
 
   Warning Dead Value
-  ImmutableArray.res:54:3-72
+  ImmutableArray.res:52:3-72
   zipByU is never used
 
   Warning Dead Value
-  ImmutableArray.res:55:3-70
+  ImmutableArray.res:53:3-70
   zipBy is never used
 
   Warning Dead Value
-  ImmutableArray.res:57:3-47
+  ImmutableArray.res:55:3-47
   unzip is never used
 
   Warning Dead Value
-  ImmutableArray.res:59:3-66
+  ImmutableArray.res:57:3-66
   concat is never used
 
   Warning Dead Value
-  ImmutableArray.res:61:3-67
+  ImmutableArray.res:59:3-67
   concatMany is never used
 
   Warning Dead Value
-  ImmutableArray.res:63:3-77
+  ImmutableArray.res:61:3-77
   slice is never used
 
   Warning Dead Value
-  ImmutableArray.res:65:3-63
+  ImmutableArray.res:63:3-63
   sliceToEnd is never used
 
   Warning Dead Value
-  ImmutableArray.res:67:3-43
+  ImmutableArray.res:65:3-43
   copy is never used
 
   Warning Dead Value
-  ImmutableArray.res:69:3-54
+  ImmutableArray.res:67:3-54
   forEachU is never used
 
   Warning Dead Value
-  ImmutableArray.res:70:3-52
+  ImmutableArray.res:68:3-52
   forEach is never used
 
   Warning Dead Value
-  ImmutableArray.res:72:3-51
+  ImmutableArray.res:70:3-51
   mapU is never used
 
   Warning Dead Value
-  ImmutableArray.res:73:3-49
+  ImmutableArray.res:71:3-49
   map is never used
 
   Warning Dead Value
-  ImmutableArray.res:75:3-71
+  ImmutableArray.res:73:3-71
   keepWithIndexU is never used
 
   Warning Dead Value
-  ImmutableArray.res:76:3-69
+  ImmutableArray.res:74:3-69
   keepWithIndex is never used
 
   Warning Dead Value
-  ImmutableArray.res:78:3-59
+  ImmutableArray.res:76:3-59
   keepMapU is never used
 
   Warning Dead Value
-  ImmutableArray.res:79:3-57
+  ImmutableArray.res:77:3-57
   keepMap is never used
 
   Warning Dead Value
-  ImmutableArray.res:81:3-72
+  ImmutableArray.res:79:3-72
   forEachWithIndexU is never used
 
   Warning Dead Value
-  ImmutableArray.res:82:3-70
+  ImmutableArray.res:80:3-70
   forEachWithIndex is never used
 
   Warning Dead Value
-  ImmutableArray.res:84:3-69
+  ImmutableArray.res:82:3-69
   mapWithIndexU is never used
 
   Warning Dead Value
-  ImmutableArray.res:85:3-67
+  ImmutableArray.res:83:3-67
   mapWithIndex is never used
 
   Warning Dead Value
-  ImmutableArray.res:87:3-64
+  ImmutableArray.res:85:3-64
   partitionU is never used
 
   Warning Dead Value
-  ImmutableArray.res:88:3-62
+  ImmutableArray.res:86:3-62
   partition is never used
 
   Warning Dead Value
-  ImmutableArray.res:90:3-58
+  ImmutableArray.res:88:3-58
   reduceU is never used
 
   Warning Dead Value
-  ImmutableArray.res:91:3-56
+  ImmutableArray.res:89:3-56
   reduce is never used
 
   Warning Dead Value
-  ImmutableArray.res:93:3-72
+  ImmutableArray.res:91:3-72
   reduceReverseU is never used
 
   Warning Dead Value
-  ImmutableArray.res:94:3-70
+  ImmutableArray.res:92:3-70
   reduceReverse is never used
 
   Warning Dead Value
-  ImmutableArray.res:96:3-91
+  ImmutableArray.res:94:3-91
   reduceReverse2U is never used
 
   Warning Dead Value
-  ImmutableArray.res:97:3-89
+  ImmutableArray.res:95:3-89
   reduceReverse2 is never used
 
   Warning Dead Value
-  ImmutableArray.res:99:3-48
+  ImmutableArray.res:97:3-48
   someU is never used
 
   Warning Dead Value
-  ImmutableArray.res:100:3-46
+  ImmutableArray.res:98:3-46
   some is never used
 
   Warning Dead Value
-  ImmutableArray.res:102:3-50
+  ImmutableArray.res:100:3-50
   everyU is never used
 
   Warning Dead Value
-  ImmutableArray.res:103:3-48
+  ImmutableArray.res:101:3-48
   every is never used
 
   Warning Dead Value
-  ImmutableArray.res:105:3-69
+  ImmutableArray.res:103:3-69
   every2U is never used
 
   Warning Dead Value
-  ImmutableArray.res:106:3-67
+  ImmutableArray.res:104:3-67
   every2 is never used
 
   Warning Dead Value
-  ImmutableArray.res:108:3-67
+  ImmutableArray.res:106:3-67
   some2U is never used
 
   Warning Dead Value
-  ImmutableArray.res:109:3-65
+  ImmutableArray.res:107:3-65
   some2 is never used
 
   Warning Dead Value
-  ImmutableArray.res:111:3-63
+  ImmutableArray.res:109:3-63
   cmpU is never used
 
   Warning Dead Value
-  ImmutableArray.res:112:3-61
+  ImmutableArray.res:110:3-61
   cmp is never used
 
   Warning Dead Value
-  ImmutableArray.res:114:3-61
+  ImmutableArray.res:112:3-61
   eqU is never used
 
   Warning Dead Value
-  ImmutableArray.res:115:3-59
+  ImmutableArray.res:113:3-59
   eq is never used
 
   Warning Dead Value
@@ -4512,215 +4495,211 @@ Forward Liveness Analysis
   getUnsafe is never used
 
   Warning Dead Value
-  ImmutableArray.resi:25:1-50
-  getUndefined is never used
-
-  Warning Dead Value
-  ImmutableArray.resi:27:1-27
+  ImmutableArray.resi:25:1-27
   shuffle is never used
 
   Warning Dead Value
-  ImmutableArray.resi:29:1-27
+  ImmutableArray.resi:27:1-27
   reverse is never used
 
   Warning Dead Value
-  ImmutableArray.resi:31:1-49
+  ImmutableArray.resi:29:1-49
   makeUninitialized is never used
 
   Warning Dead Value
-  ImmutableArray.resi:33:1-41
+  ImmutableArray.resi:31:1-41
   makeUninitializedUnsafe is never used
 
   Warning Dead Value
-  ImmutableArray.resi:35:1-28
+  ImmutableArray.resi:33:1-28
   make is never used
 
   Warning Dead Value
-  ImmutableArray.resi:37:1-31
+  ImmutableArray.resi:35:1-31
   range is never used
 
   Warning Dead Value
-  ImmutableArray.resi:39:1-45
+  ImmutableArray.resi:37:1-45
   rangeBy is never used
 
   Warning Dead Value
-  ImmutableArray.resi:41:1-40
+  ImmutableArray.resi:39:1-40
   makeByU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:42:1-37
+  ImmutableArray.resi:40:1-37
   makeBy is never used
 
   Warning Dead Value
-  ImmutableArray.resi:44:1-50
+  ImmutableArray.resi:42:1-50
   makeByAndShuffleU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:45:1-47
+  ImmutableArray.resi:43:1-47
   makeByAndShuffle is never used
 
   Warning Dead Value
-  ImmutableArray.resi:47:1-38
+  ImmutableArray.resi:45:1-38
   zip is never used
 
   Warning Dead Value
-  ImmutableArray.resi:49:1-51
+  ImmutableArray.resi:47:1-51
   zipByU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:50:1-50
+  ImmutableArray.resi:48:1-50
   zipBy is never used
 
   Warning Dead Value
-  ImmutableArray.resi:52:1-40
+  ImmutableArray.resi:50:1-40
   unzip is never used
 
   Warning Dead Value
-  ImmutableArray.resi:54:1-35
+  ImmutableArray.resi:52:1-35
   concat is never used
 
   Warning Dead Value
-  ImmutableArray.resi:56:1-33
+  ImmutableArray.resi:54:1-33
   concatMany is never used
 
   Warning Dead Value
-  ImmutableArray.resi:58:1-52
+  ImmutableArray.resi:56:1-52
   slice is never used
 
   Warning Dead Value
-  ImmutableArray.resi:60:1-37
+  ImmutableArray.resi:58:1-37
   sliceToEnd is never used
 
   Warning Dead Value
-  ImmutableArray.resi:62:1-24
+  ImmutableArray.resi:60:1-24
   copy is never used
 
   Warning Dead Value
-  ImmutableArray.resi:64:1-43
+  ImmutableArray.resi:62:1-43
   forEachU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:65:1-40
+  ImmutableArray.resi:63:1-40
   forEach is never used
 
   Warning Dead Value
-  ImmutableArray.resi:67:1-38
+  ImmutableArray.resi:65:1-38
   mapU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:68:1-35
+  ImmutableArray.resi:66:1-35
   map is never used
 
   Warning Dead Value
-  ImmutableArray.resi:70:1-55
+  ImmutableArray.resi:68:1-55
   keepWithIndexU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:71:1-54
+  ImmutableArray.resi:69:1-54
   keepWithIndex is never used
 
   Warning Dead Value
-  ImmutableArray.resi:73:1-50
+  ImmutableArray.resi:71:1-50
   keepMapU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:74:1-47
+  ImmutableArray.resi:72:1-47
   keepMap is never used
 
   Warning Dead Value
-  ImmutableArray.resi:76:1-57
+  ImmutableArray.resi:74:1-57
   forEachWithIndexU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:77:1-56
+  ImmutableArray.resi:75:1-56
   forEachWithIndex is never used
 
   Warning Dead Value
-  ImmutableArray.resi:79:1-52
+  ImmutableArray.resi:77:1-52
   mapWithIndexU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:80:1-51
+  ImmutableArray.resi:78:1-51
   mapWithIndex is never used
 
   Warning Dead Value
-  ImmutableArray.resi:82:1-55
+  ImmutableArray.resi:80:1-55
   partitionU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:83:1-52
+  ImmutableArray.resi:81:1-52
   partition is never used
 
   Warning Dead Value
-  ImmutableArray.resi:85:1-46
+  ImmutableArray.resi:83:1-46
   reduceU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:86:1-45
+  ImmutableArray.resi:84:1-45
   reduce is never used
 
   Warning Dead Value
-  ImmutableArray.resi:88:1-53
+  ImmutableArray.resi:86:1-53
   reduceReverseU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:89:1-52
+  ImmutableArray.resi:87:1-52
   reduceReverse is never used
 
   Warning Dead Value
-  ImmutableArray.resi:91:1-65
+  ImmutableArray.resi:89:1-65
   reduceReverse2U is never used
 
   Warning Dead Value
-  ImmutableArray.resi:92:1-64
+  ImmutableArray.resi:90:1-64
   reduceReverse2 is never used
 
   Warning Dead Value
-  ImmutableArray.resi:94:1-40
+  ImmutableArray.resi:92:1-40
   someU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:95:1-37
+  ImmutableArray.resi:93:1-37
   some is never used
 
   Warning Dead Value
-  ImmutableArray.resi:97:1-41
+  ImmutableArray.resi:95:1-41
   everyU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:98:1-38
+  ImmutableArray.resi:96:1-38
   every is never used
 
   Warning Dead Value
-  ImmutableArray.resi:100:1-53
+  ImmutableArray.resi:98:1-53
   every2U is never used
 
   Warning Dead Value
-  ImmutableArray.resi:101:1-52
+  ImmutableArray.resi:99:1-52
   every2 is never used
 
   Warning Dead Value
-  ImmutableArray.resi:103:1-52
+  ImmutableArray.resi:101:1-52
   some2U is never used
 
   Warning Dead Value
-  ImmutableArray.resi:104:1-51
+  ImmutableArray.resi:102:1-51
   some2 is never used
 
   Warning Dead Value
-  ImmutableArray.resi:106:1-48
+  ImmutableArray.resi:104:1-48
   cmpU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:107:1-47
+  ImmutableArray.resi:105:1-47
   cmp is never used
 
   Warning Dead Value
-  ImmutableArray.resi:109:1-49
+  ImmutableArray.resi:107:1-49
   eqU is never used
 
   Warning Dead Value
-  ImmutableArray.resi:110:1-48
+  ImmutableArray.resi:108:1-48
   eq is never used
 
   Warning Dead Type
@@ -5255,4 +5234,4 @@ Forward Liveness Analysis
   OptArg.res:26:1-70
   optional argument c of function wrapfourArgs is always supplied (2 calls)
   
-  Analysis reported 320 issues (Incorrect Dead Annotation:1, Warning Dead Exception:2, Warning Dead Module:22, Warning Dead Type:93, Warning Dead Value:179, Warning Dead Value With Side Effects:5, Warning Redundant Optional Argument:6, Warning Unused Argument:12)
+  Analysis reported 318 issues (Incorrect Dead Annotation:1, Warning Dead Exception:2, Warning Dead Module:22, Warning Dead Type:93, Warning Dead Value:177, Warning Dead Value With Side Effects:5, Warning Redundant Optional Argument:6, Warning Unused Argument:12)
diff --git a/tests/analysis_tests/tests-reanalyze/deadcode/src/ImmutableArray.res b/tests/analysis_tests/tests-reanalyze/deadcode/src/ImmutableArray.res
index 8ed5e0809ee..fa3f7f418ce 100644
--- a/tests/analysis_tests/tests-reanalyze/deadcode/src/ImmutableArray.res
+++ b/tests/analysis_tests/tests-reanalyze/deadcode/src/ImmutableArray.res
@@ -27,8 +27,6 @@ module Array = {
 
   let getUnsafe = (a, x) => Array.getUnsafe(a->fromT, x)
 
-  let getUndefined = (a, x) => Array.getUndefined(a->fromT, x)
-
   let shuffle = x => Array.shuffle(x->fromT)->toT
 
   let reverse = x => Array.reverse(x->fromT)->toT
@@ -116,4 +114,3 @@ module Array = {
 }
 
 include Array
-
diff --git a/tests/analysis_tests/tests-reanalyze/deadcode/src/ImmutableArray.resi b/tests/analysis_tests/tests-reanalyze/deadcode/src/ImmutableArray.resi
index d1bdc068a0a..a0695a8aac6 100644
--- a/tests/analysis_tests/tests-reanalyze/deadcode/src/ImmutableArray.resi
+++ b/tests/analysis_tests/tests-reanalyze/deadcode/src/ImmutableArray.resi
@@ -22,8 +22,6 @@ let getExn: (t<'a>, int) => 'a
 
 let getUnsafe: (t<'a>, int) => 'a
 
-let getUndefined: (t<'a>, int) => Js.undefined<'a>
-
 let shuffle: t<'a> => t<'a>
 
 let reverse: t<'a> => t<'a>
@@ -108,4 +106,3 @@ let cmp: (t<'a>, t<'a>, ('a, 'a) => int) => int
 
 let eqU: (t<'a>, t<'a>, ('a, 'a) => bool) => bool
 let eq: (t<'a>, t<'a>, ('a, 'a) => bool) => bool
-
diff --git a/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res b/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res
index 458f61767b8..55d271d9609 100644
--- a/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res
+++ b/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res
@@ -27,8 +27,6 @@ module Array = {
 
   let getUnsafe = (a, x) => Array.getUnsafe(a->fromT, x)
 
-  let getUndefined = (a, x) => Array.getUndefined(a->fromT, x)
-
   let shuffle = x => Array.shuffle(x->fromT)->toT
 
   let reverse = x => Array.reverse(x->fromT)->toT
diff --git a/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res.js b/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res.js
index bb78304f0a1..624a05dd831 100644
--- a/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res.js
+++ b/tests/gentype_tests/typescript-react-example/src/ImmutableArray.res.js
@@ -26,10 +26,6 @@ function getUnsafe(a, x) {
   return a[x];
 }
 
-function getUndefined(a, x) {
-  return a[x];
-}
-
 let shuffle = Belt_Array.shuffle;
 
 let reverse = Belt_Array.reverse;
@@ -153,7 +149,6 @@ export {
   get,
   getExn,
   getUnsafe,
-  getUndefined,
   shuffle,
   reverse,
   makeUninitialized,
diff --git a/tests/gentype_tests/typescript-react-example/src/ImmutableArray.resi b/tests/gentype_tests/typescript-react-example/src/ImmutableArray.resi
index adef7af76a2..6616546510e 100644
--- a/tests/gentype_tests/typescript-react-example/src/ImmutableArray.resi
+++ b/tests/gentype_tests/typescript-react-example/src/ImmutableArray.resi
@@ -22,8 +22,6 @@ let getExn: (t<'a>, int) => 'a
 
 let getUnsafe: (t<'a>, int) => 'a
 
-let getUndefined: (t<'a>, int) => Js.undefined<'a>
-
 let shuffle: t<'a> => t<'a>
 
 let reverse: t<'a> => t<'a>
diff --git a/tests/tests/src/bs_mutable_set_test.mjs b/tests/tests/src/bs_mutable_set_test.mjs
index 0cd817dd599..6b9f967a068 100644
--- a/tests/tests/src/bs_mutable_set_test.mjs
+++ b/tests/tests/src/bs_mutable_set_test.mjs
@@ -17,8 +17,8 @@ Mocha.describe("Bs_mutable_set_test", () => {
     Test_utils.ok("File \"bs_mutable_set_test.res\", line 19, characters 7-14", Belt_MutableSetInt.removeCheck(u, 20));
     Test_utils.eq("File \"bs_mutable_set_test.res\", line 20, characters 7-14", Belt_MutableSetInt.size(u), 28);
     let r = Array_data_util.randomRange(0, 30);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 22, characters 7-14", 29 === Belt_MutableSetInt.maxUndefined(u));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 23, characters 7-14", 1 === Belt_MutableSetInt.minUndefined(u));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 22, characters 7-14", Belt_MutableSetInt.maximum(u), 29);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 23, characters 7-14", Belt_MutableSetInt.minimum(u), 1);
     Belt_MutableSetInt.add(u, 3);
     for (let i = 0, i_finish = r.length; i < i_finish; ++i) {
       Belt_MutableSetInt.remove(u, r[i]);
@@ -76,48 +76,46 @@ Mocha.describe("Bs_mutable_set_test", () => {
     Test_utils.ok("File \"bs_mutable_set_test.res\", line 85, characters 7-14", Belt_MutableSetInt.isEmpty(Belt_MutableSetInt.make()));
     Test_utils.eq("File \"bs_mutable_set_test.res\", line 86, characters 7-14", Belt_MutableSetInt.minimum(v), 500);
     Test_utils.eq("File \"bs_mutable_set_test.res\", line 87, characters 7-14", Belt_MutableSetInt.maximum(v), 2000);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 88, characters 7-14", Belt_MutableSetInt.minUndefined(v), 500);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 89, characters 7-14", Belt_MutableSetInt.maxUndefined(v), 2000);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 90, characters 7-14", Belt_MutableSetInt.reduce(v, 0, (x, y) => x + y | 0), 1876250);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 91, characters 7-14", Belt_List.eq(Belt_MutableSetInt.toList(v), Belt_List.makeBy(1501, i => i + 500 | 0), (x, y) => x === y));
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 92, characters 7-14", Belt_MutableSetInt.toArray(v), Array_data_util.range(500, 2000));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 88, characters 7-14", Belt_MutableSetInt.reduce(v, 0, (x, y) => x + y | 0), 1876250);
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 89, characters 7-14", Belt_List.eq(Belt_MutableSetInt.toList(v), Belt_List.makeBy(1501, i => i + 500 | 0), (x, y) => x === y));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 90, characters 7-14", Belt_MutableSetInt.toArray(v), Array_data_util.range(500, 2000));
     Belt_MutableSetInt.checkInvariantInternal(v);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 94, characters 7-14", Belt_MutableSetInt.get(v, 3), undefined);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 95, characters 7-14", Belt_MutableSetInt.get(v, 1200), 1200);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 92, characters 7-14", Belt_MutableSetInt.get(v, 3), undefined);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 93, characters 7-14", Belt_MutableSetInt.get(v, 1200), 1200);
     let match = Belt_MutableSetInt.split(v, 1000);
     let match$1 = match[0];
     let bb = match$1[1];
     let aa = match$1[0];
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 97, characters 7-14", match[1]);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 98, characters 7-14", Belt_Array.eq(Belt_MutableSetInt.toArray(aa), Array_data_util.range(500, 999), (x, y) => x === y));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 99, characters 7-14", Belt_Array.eq(Belt_MutableSetInt.toArray(bb), Array_data_util.range(1001, 2000), (x, y) => x === y));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 100, characters 7-14", Belt_MutableSetInt.subset(aa, v));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 101, characters 7-14", Belt_MutableSetInt.subset(bb, v));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 102, characters 7-14", Belt_MutableSetInt.isEmpty(Belt_MutableSetInt.intersect(aa, bb)));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 95, characters 7-14", match[1]);
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 96, characters 7-14", Belt_Array.eq(Belt_MutableSetInt.toArray(aa), Array_data_util.range(500, 999), (x, y) => x === y));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 97, characters 7-14", Belt_Array.eq(Belt_MutableSetInt.toArray(bb), Array_data_util.range(1001, 2000), (x, y) => x === y));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 98, characters 7-14", Belt_MutableSetInt.subset(aa, v));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 99, characters 7-14", Belt_MutableSetInt.subset(bb, v));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 100, characters 7-14", Belt_MutableSetInt.isEmpty(Belt_MutableSetInt.intersect(aa, bb)));
     let c = Belt_MutableSetInt.removeCheck(v, 1000);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 104, characters 7-14", c);
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 102, characters 7-14", c);
     let match$2 = Belt_MutableSetInt.split(v, 1000);
     let match$3 = match$2[0];
     let bb$1 = match$3[1];
     let aa$1 = match$3[0];
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 106, characters 7-14", !match$2[1]);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 107, characters 7-14", Belt_Array.eq(Belt_MutableSetInt.toArray(aa$1), Array_data_util.range(500, 999), (x, y) => x === y));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 108, characters 7-14", Belt_Array.eq(Belt_MutableSetInt.toArray(bb$1), Array_data_util.range(1001, 2000), (x, y) => x === y));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 109, characters 7-14", Belt_MutableSetInt.subset(aa$1, v));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 110, characters 7-14", Belt_MutableSetInt.subset(bb$1, v));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 111, characters 7-14", Belt_MutableSetInt.isEmpty(Belt_MutableSetInt.intersect(aa$1, bb$1)));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 104, characters 7-14", !match$2[1]);
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 105, characters 7-14", Belt_Array.eq(Belt_MutableSetInt.toArray(aa$1), Array_data_util.range(500, 999), (x, y) => x === y));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 106, characters 7-14", Belt_Array.eq(Belt_MutableSetInt.toArray(bb$1), Array_data_util.range(1001, 2000), (x, y) => x === y));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 107, characters 7-14", Belt_MutableSetInt.subset(aa$1, v));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 108, characters 7-14", Belt_MutableSetInt.subset(bb$1, v));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 109, characters 7-14", Belt_MutableSetInt.isEmpty(Belt_MutableSetInt.intersect(aa$1, bb$1)));
   });
   Mocha.test("mutable set union operations", () => {
     let aa = Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 100));
     let bb = Belt_MutableSetInt.fromArray(Array_data_util.randomRange(40, 120));
     let cc = Belt_MutableSetInt.union(aa, bb);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 121, characters 7-14", Belt_MutableSetInt.eq(cc, Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 120))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 124, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.union(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 40))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 119, characters 7-14", Belt_MutableSetInt.eq(cc, Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 120))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 122, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.union(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 40))));
     let dd = Belt_MutableSetInt.intersect(aa, bb);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 128, characters 7-14", Belt_MutableSetInt.eq(dd, Belt_MutableSetInt.fromArray(Array_data_util.randomRange(40, 100))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 129, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.make()));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 130, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))), Belt_MutableSetInt.make()));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 131, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray([
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 126, characters 7-14", Belt_MutableSetInt.eq(dd, Belt_MutableSetInt.fromArray(Array_data_util.randomRange(40, 100))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 127, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.make()));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 128, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))), Belt_MutableSetInt.make()));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 129, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray([
       1,
       3,
       4,
@@ -135,11 +133,11 @@ Mocha.describe("Bs_mutable_set_test", () => {
       4,
       5
     ])));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 132, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(aa, bb), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 39))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 133, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(bb, aa), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(101, 120))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 135, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 139, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 144, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, -1))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 130, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(aa, bb), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 39))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 131, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(bb, aa), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(101, 120))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 133, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 137, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 142, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, -1))));
   });
   Mocha.test("mutable set keep/partition operations", () => {
     let a0 = Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 1000));
@@ -148,8 +146,8 @@ Mocha.describe("Bs_mutable_set_test", () => {
     let match = Belt_MutableSetInt.partition(a0, x => x % 2 === 0);
     let a4 = match[1];
     let a3 = match[0];
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 153, characters 7-14", Belt_MutableSetInt.eq(a1, a3));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 154, characters 7-14", Belt_MutableSetInt.eq(a2, a4));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 151, characters 7-14", Belt_MutableSetInt.eq(a1, a3));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 152, characters 7-14", Belt_MutableSetInt.eq(a2, a4));
     Belt_List.forEach({
       hd: a0,
       tl: {
@@ -173,45 +171,45 @@ Mocha.describe("Bs_mutable_set_test", () => {
       Belt_MutableSetInt.add(v, i);
     }
     Belt_MutableSetInt.checkInvariantInternal(v);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 164, characters 7-14", Belt_Range.every(0, 100000, i => Belt_MutableSetInt.has(v, i)));
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 165, characters 7-14", Belt_MutableSetInt.size(v), 100001);
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 162, characters 7-14", Belt_Range.every(0, 100000, i => Belt_MutableSetInt.has(v, i)));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 163, characters 7-14", Belt_MutableSetInt.size(v), 100001);
   });
   Mocha.test("mutable set merge operations", () => {
     let u = Belt_Array.concat(Array_data_util.randomRange(30, 100), Array_data_util.randomRange(40, 120));
     let v = Belt_MutableSetInt.make();
     Belt_MutableSetInt.mergeMany(v, u);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 172, characters 7-14", Belt_MutableSetInt.size(v), 91);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 173, characters 7-14", Belt_MutableSetInt.toArray(v), Array_data_util.range(30, 120));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 170, characters 7-14", Belt_MutableSetInt.size(v), 91);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 171, characters 7-14", Belt_MutableSetInt.toArray(v), Array_data_util.range(30, 120));
   });
   Mocha.test("mutable set remove many operations", () => {
     let u = Belt_Array.concat(Array_data_util.randomRange(0, 100000), Array_data_util.randomRange(0, 100));
     let v = Belt_MutableSetInt.fromArray(u);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 179, characters 7-14", Belt_MutableSetInt.size(v), 100001);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 177, characters 7-14", Belt_MutableSetInt.size(v), 100001);
     let u$1 = Array_data_util.randomRange(50000, 80000);
     for (let i = 0, i_finish = u$1.length; i < i_finish; ++i) {
       Belt_MutableSetInt.remove(v, i);
     }
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 186, characters 7-14", Belt_MutableSetInt.size(v), 70000);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 184, characters 7-14", Belt_MutableSetInt.size(v), 70000);
     let vv = Array_data_util.randomRange(0, 100000);
     for (let i$1 = 0, i_finish$1 = vv.length; i$1 < i_finish$1; ++i$1) {
       Belt_MutableSetInt.remove(v, vv[i$1]);
     }
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 192, characters 7-14", Belt_MutableSetInt.size(v), 0);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 193, characters 7-14", Belt_MutableSetInt.isEmpty(v));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 190, characters 7-14", Belt_MutableSetInt.size(v), 0);
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 191, characters 7-14", Belt_MutableSetInt.isEmpty(v));
   });
   Mocha.test("mutable set min/max operations", () => {
     let v = Belt_MutableSetInt.fromArray(Belt_Array.makeBy(30, i => i));
     Belt_MutableSetInt.remove(v, 30);
     Belt_MutableSetInt.remove(v, 29);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 200, characters 7-14", 28 === Belt_MutableSetInt.maxUndefined(v));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 198, characters 7-14", Belt_MutableSetInt.maximum(v), 28);
     Belt_MutableSetInt.remove(v, 0);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 202, characters 7-14", 1 === Belt_MutableSetInt.minUndefined(v));
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 203, characters 7-14", Belt_MutableSetInt.size(v), 28);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 200, characters 7-14", Belt_MutableSetInt.minimum(v), 1);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 201, characters 7-14", Belt_MutableSetInt.size(v), 28);
     let vv = Array_data_util.randomRange(1, 28);
     for (let i = 0, i_finish = vv.length; i < i_finish; ++i) {
       Belt_MutableSetInt.remove(v, vv[i]);
     }
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 208, characters 7-14", Belt_MutableSetInt.size(v), 0);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 206, characters 7-14", Belt_MutableSetInt.size(v), 0);
   });
   Mocha.test("mutable set fromSortedArrayUnsafe", () => {
     let id = (loc, x) => {
@@ -219,31 +217,31 @@ Mocha.describe("Bs_mutable_set_test", () => {
       Belt_MutableSetInt.checkInvariantInternal(u);
       Test_utils.ok(loc, Belt_Array.every2(Belt_MutableSetInt.toArray(u), x, (x, y) => x === y));
     };
-    id("File \"bs_mutable_set_test.res\", line 218, characters 7-14", []);
-    id("File \"bs_mutable_set_test.res\", line 219, characters 7-14", [0]);
-    id("File \"bs_mutable_set_test.res\", line 220, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 216, characters 7-14", []);
+    id("File \"bs_mutable_set_test.res\", line 217, characters 7-14", [0]);
+    id("File \"bs_mutable_set_test.res\", line 218, characters 7-14", [
       0,
       1
     ]);
-    id("File \"bs_mutable_set_test.res\", line 221, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 219, characters 7-14", [
       0,
       1,
       2
     ]);
-    id("File \"bs_mutable_set_test.res\", line 222, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 220, characters 7-14", [
       0,
       1,
       2,
       3
     ]);
-    id("File \"bs_mutable_set_test.res\", line 223, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 221, characters 7-14", [
       0,
       1,
       2,
       3,
       4
     ]);
-    id("File \"bs_mutable_set_test.res\", line 224, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 222, characters 7-14", [
       0,
       1,
       2,
@@ -251,7 +249,7 @@ Mocha.describe("Bs_mutable_set_test", () => {
       4,
       5
     ]);
-    id("File \"bs_mutable_set_test.res\", line 225, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 223, characters 7-14", [
       0,
       1,
       2,
@@ -259,7 +257,7 @@ Mocha.describe("Bs_mutable_set_test", () => {
       4,
       6
     ]);
-    id("File \"bs_mutable_set_test.res\", line 226, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 224, characters 7-14", [
       0,
       1,
       2,
@@ -268,7 +266,7 @@ Mocha.describe("Bs_mutable_set_test", () => {
       6,
       7
     ]);
-    id("File \"bs_mutable_set_test.res\", line 227, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 225, characters 7-14", [
       0,
       1,
       2,
@@ -278,7 +276,7 @@ Mocha.describe("Bs_mutable_set_test", () => {
       7,
       8
     ]);
-    id("File \"bs_mutable_set_test.res\", line 228, characters 7-14", [
+    id("File \"bs_mutable_set_test.res\", line 226, characters 7-14", [
       0,
       1,
       2,
@@ -289,7 +287,7 @@ Mocha.describe("Bs_mutable_set_test", () => {
       8,
       9
     ]);
-    id("File \"bs_mutable_set_test.res\", line 229, characters 7-14", Array_data_util.range(0, 1000));
+    id("File \"bs_mutable_set_test.res\", line 227, characters 7-14", Array_data_util.range(0, 1000));
   });
   Mocha.test("mutable set keep/partition with mod 8", () => {
     let v = Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 1000));
@@ -299,35 +297,35 @@ Mocha.describe("Bs_mutable_set_test", () => {
     for (let i = 0; i <= 200; ++i) {
       Belt_MutableSetInt.remove(v, i);
     }
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 240, characters 7-14", Belt_MutableSetInt.size(copyV), 126);
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 241, characters 7-14", Belt_MutableSetInt.toArray(copyV), Belt_Array.makeBy(126, i => (i << 3)));
-    Test_utils.eq("File \"bs_mutable_set_test.res\", line 242, characters 7-14", Belt_MutableSetInt.size(v), 800);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 243, characters 7-14", Belt_MutableSetInt.eq(copyV, match[0]));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 244, characters 7-14", Belt_MutableSetInt.eq(cc, match[1]));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 238, characters 7-14", Belt_MutableSetInt.size(copyV), 126);
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 239, characters 7-14", Belt_MutableSetInt.toArray(copyV), Belt_Array.makeBy(126, i => (i << 3)));
+    Test_utils.eq("File \"bs_mutable_set_test.res\", line 240, characters 7-14", Belt_MutableSetInt.size(v), 800);
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 241, characters 7-14", Belt_MutableSetInt.eq(copyV, match[0]));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 242, characters 7-14", Belt_MutableSetInt.eq(cc, match[1]));
   });
   Mocha.test("mutable set split operations", () => {
     let v = Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 1000));
     let match = Belt_MutableSetInt.split(v, 400);
     let match$1 = match[0];
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 250, characters 7-14", Belt_MutableSetInt.eq(match$1[0], Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 399))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 251, characters 7-14", Belt_MutableSetInt.eq(match$1[1], Belt_MutableSetInt.fromArray(Array_data_util.randomRange(401, 1000))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 248, characters 7-14", Belt_MutableSetInt.eq(match$1[0], Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 399))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 249, characters 7-14", Belt_MutableSetInt.eq(match$1[1], Belt_MutableSetInt.fromArray(Array_data_util.randomRange(401, 1000))));
     let d = Belt_MutableSetInt.fromArray(Belt_Array.map(Array_data_util.randomRange(0, 1000), x => (x << 1)));
     let match$2 = Belt_MutableSetInt.split(d, 1001);
     let match$3 = match$2[0];
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 254, characters 7-14", Belt_MutableSetInt.eq(match$3[0], Belt_MutableSetInt.fromArray(Belt_Array.makeBy(501, x => (x << 1)))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 255, characters 7-14", Belt_MutableSetInt.eq(match$3[1], Belt_MutableSetInt.fromArray(Belt_Array.makeBy(500, x => 1002 + (x << 1) | 0))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 252, characters 7-14", Belt_MutableSetInt.eq(match$3[0], Belt_MutableSetInt.fromArray(Belt_Array.makeBy(501, x => (x << 1)))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 253, characters 7-14", Belt_MutableSetInt.eq(match$3[1], Belt_MutableSetInt.fromArray(Belt_Array.makeBy(500, x => 1002 + (x << 1) | 0))));
   });
   Mocha.test("mutable set final union operations", () => {
     let aa = Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 100));
     let bb = Belt_MutableSetInt.fromArray(Array_data_util.randomRange(40, 120));
     let cc = Belt_MutableSetInt.union(aa, bb);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 265, characters 7-14", Belt_MutableSetInt.eq(cc, Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 120))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 268, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.union(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 40))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 263, characters 7-14", Belt_MutableSetInt.eq(cc, Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 120))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 266, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.union(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 40))));
     let dd = Belt_MutableSetInt.intersect(aa, bb);
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 272, characters 7-14", Belt_MutableSetInt.eq(dd, Belt_MutableSetInt.fromArray(Array_data_util.randomRange(40, 100))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 273, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.make()));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 274, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))), Belt_MutableSetInt.make()));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 275, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray([
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 270, characters 7-14", Belt_MutableSetInt.eq(dd, Belt_MutableSetInt.fromArray(Array_data_util.randomRange(40, 100))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 271, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.make()));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 272, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))), Belt_MutableSetInt.make()));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 273, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.intersect(Belt_MutableSetInt.fromArray([
       1,
       3,
       4,
@@ -345,11 +343,11 @@ Mocha.describe("Bs_mutable_set_test", () => {
       4,
       5
     ])));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 276, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(aa, bb), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 39))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 277, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(bb, aa), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(101, 120))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 279, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 283, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))));
-    Test_utils.ok("File \"bs_mutable_set_test.res\", line 288, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, -1))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 274, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(aa, bb), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 39))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 275, characters 7-14", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(bb, aa), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(101, 120))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 277, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 281, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(21, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20))));
+    Test_utils.ok("File \"bs_mutable_set_test.res\", line 286, characters 6-13", Belt_MutableSetInt.eq(Belt_MutableSetInt.diff(Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 20)), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, 40))), Belt_MutableSetInt.fromArray(Array_data_util.randomRange(0, -1))));
   });
 });
 
diff --git a/tests/tests/src/bs_mutable_set_test.res b/tests/tests/src/bs_mutable_set_test.res
index 11a8375bfaf..d1122933710 100644
--- a/tests/tests/src/bs_mutable_set_test.res
+++ b/tests/tests/src/bs_mutable_set_test.res
@@ -19,8 +19,8 @@ describe(__MODULE__, () => {
     ok(__LOC__, N.removeCheck(u, 20))
     eq(__LOC__, N.size(u), 28)
     let r = I.randomRange(0, 30)
-    ok(__LOC__, Js.eqUndefined(29, N.maxUndefined(u)))
-    ok(__LOC__, Js.eqUndefined(1, N.minUndefined(u)))
+    eq(__LOC__, N.maximum(u), Some(29))
+    eq(__LOC__, N.minimum(u), Some(1))
     N.add(u, 3)
     for i in 0 to A.length(r) - 1 {
       N.remove(u, A.getUnsafe(r, i))
@@ -85,8 +85,6 @@ describe(__MODULE__, () => {
     ok(__LOC__, N.isEmpty(empty()))
     eq(__LOC__, N.minimum(v), Some(500))
     eq(__LOC__, N.maximum(v), Some(2000))
-    eq(__LOC__, N.minUndefined(v), Js.Undefined.return(500))
-    eq(__LOC__, N.maxUndefined(v), Js.Undefined.return(2000))
     eq(__LOC__, N.reduce(v, 0, (x, y) => x + y), (500 + 2000) / 2 * 1501)
     ok(__LOC__, L.eq(N.toList(v), L.makeBy(1_501, i => i + 500), (x, y) => x == y))
     eq(__LOC__, N.toArray(v), I.range(500, 2000))
@@ -197,9 +195,9 @@ describe(__MODULE__, () => {
     let v = N.fromArray(A.makeBy(30, i => i))
     N.remove(v, 30)
     N.remove(v, 29)
-    ok(__LOC__, Js.eqUndefined(28, N.maxUndefined(v)))
+    eq(__LOC__, N.maximum(v), Some(28))
     N.remove(v, 0)
-    ok(__LOC__, Js.eqUndefined(1, N.minUndefined(v)))
+    eq(__LOC__, N.minimum(v), Some(1))
     eq(__LOC__, N.size(v), 28)
     let vv = I.randomRange(1, 28)
     for i in 0 to A.length(vv) - 1 {
diff --git a/tests/tests/src/bs_poly_map_test.mjs b/tests/tests/src/bs_poly_map_test.mjs
index 99003ea15c9..4a24f1e4c10 100644
--- a/tests/tests/src/bs_poly_map_test.mjs
+++ b/tests/tests/src/bs_poly_map_test.mjs
@@ -8,6 +8,7 @@ import * as Belt_Array from "@rescript/runtime/lib/es6/Belt_Array.mjs";
 import * as Test_utils from "./test_utils.mjs";
 import * as Primitive_int from "@rescript/runtime/lib/es6/Primitive_int.mjs";
 import * as Array_data_util from "./array_data_util.mjs";
+import * as Primitive_object from "@rescript/runtime/lib/es6/Primitive_object.mjs";
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.mjs";
 
 let Icmp = Belt_Id.comparable(Primitive_int.compare);
@@ -85,11 +86,11 @@ Mocha.describe("Bs_poly_map_test", () => {
     Test_utils.ok("File \"bs_poly_map_test.res\", line 88, characters 7-14", a5 === a6);
     Test_utils.ok("File \"bs_poly_map_test.res\", line 89, characters 7-14", Belt_Map.has(a0, 3));
     Test_utils.ok("File \"bs_poly_map_test.res\", line 90, characters 7-14", !Belt_Map.has(a5, 3));
-    Test_utils.ok("File \"bs_poly_map_test.res\", line 91, characters 7-14", 3 === Belt_Map.getUndefined(a0, 3));
-    Test_utils.ok("File \"bs_poly_map_test.res\", line 92, characters 7-14", 33 === Belt_Map.getUndefined(a1, 3));
-    Test_utils.ok("File \"bs_poly_map_test.res\", line 93, characters 7-14", Belt_Map.getUndefined(a2, 3) === undefined);
-    Test_utils.ok("File \"bs_poly_map_test.res\", line 95, characters 7-14", 11 === Belt_Map.getUndefined(a3, 3));
-    Test_utils.ok("File \"bs_poly_map_test.res\", line 96, characters 7-14", Belt_Map.getUndefined(a4, 3) === undefined);
+    Test_utils.ok("File \"bs_poly_map_test.res\", line 91, characters 7-14", Primitive_object.equal(Belt_Map.get(a0, 3), 3));
+    Test_utils.ok("File \"bs_poly_map_test.res\", line 92, characters 7-14", Primitive_object.equal(Belt_Map.get(a1, 3), 33));
+    Test_utils.ok("File \"bs_poly_map_test.res\", line 93, characters 7-14", Belt_Map.get(a2, 3) === undefined);
+    Test_utils.ok("File \"bs_poly_map_test.res\", line 95, characters 7-14", Primitive_object.equal(Belt_Map.get(a3, 3), 11));
+    Test_utils.ok("File \"bs_poly_map_test.res\", line 96, characters 7-14", Belt_Map.get(a4, 3) === undefined);
     let a7 = Belt_Map.removeMany(a0, [
       7,
       8,
diff --git a/tests/tests/src/bs_poly_map_test.res b/tests/tests/src/bs_poly_map_test.res
index 53f06932665..42c0ff5438f 100644
--- a/tests/tests/src/bs_poly_map_test.res
+++ b/tests/tests/src/bs_poly_map_test.res
@@ -88,12 +88,12 @@ describe(__MODULE__, () => {
     ok(__LOC__, a5 === a6)
     ok(__LOC__, M.has(a0, 3))
     ok(__LOC__, !M.has(a5, 3))
-    ok(__LOC__, Js.eqUndefined(3, M.getUndefined(a0, 3)))
-    ok(__LOC__, Js.eqUndefined(33, M.getUndefined(a1, 3)))
-    ok(__LOC__, M.getUndefined(a2, 3) == Js.undefined)
+    ok(__LOC__, M.get(a0, 3) == Some(3))
+    ok(__LOC__, M.get(a1, 3) == Some(33))
+    ok(__LOC__, M.get(a2, 3) == None)
 
-    ok(__LOC__, Js.eqUndefined(11, M.getUndefined(a3, 3)))
-    ok(__LOC__, M.getUndefined(a4, 3) == Js.undefined)
+    ok(__LOC__, M.get(a3, 3) == Some(11))
+    ok(__LOC__, M.get(a4, 3) == None)
 
     let a7 = M.removeMany(a0, [7, 8, 0, 1, 3, 2, 4, 922, 4, 5, 6])
     eq(__LOC__, M.keysToArray(a7), [9, 10])
diff --git a/tests/tests/src/bs_poly_mutable_set_test.mjs b/tests/tests/src/bs_poly_mutable_set_test.mjs
index 058a61c5535..40c03e50675 100644
--- a/tests/tests/src/bs_poly_mutable_set_test.mjs
+++ b/tests/tests/src/bs_poly_mutable_set_test.mjs
@@ -28,8 +28,8 @@ Mocha.describe("Bs_poly_mutable_set_test", () => {
     Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 18, characters 7-14", Belt_MutableSet.removeCheck(u, 20));
     Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 19, characters 7-14", Belt_MutableSet.size(u), 28);
     let r = Array_data_util.randomRange(0, 30);
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 21, characters 7-14", 29 === Belt_MutableSet.maxUndefined(u));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 22, characters 7-14", 1 === Belt_MutableSet.minUndefined(u));
+    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 21, characters 7-14", Belt_MutableSet.maximum(u), 29);
+    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 22, characters 7-14", Belt_MutableSet.minimum(u), 1);
     Belt_MutableSet.add(u, 3);
     for (let i = 0, i_finish = r.length; i < i_finish; ++i) {
       Belt_MutableSet.remove(u, r[i]);
@@ -87,48 +87,46 @@ Mocha.describe("Bs_poly_mutable_set_test", () => {
     Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 84, characters 7-14", Belt_MutableSet.isEmpty(Belt_MutableSet.make(IntCmp)));
     Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 85, characters 7-14", Belt_MutableSet.minimum(v), 500);
     Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 86, characters 7-14", Belt_MutableSet.maximum(v), 2000);
-    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 87, characters 7-14", Belt_MutableSet.minUndefined(v), 500);
-    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 88, characters 7-14", Belt_MutableSet.maxUndefined(v), 2000);
-    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 89, characters 7-14", Belt_MutableSet.reduce(v, 0, (x, y) => x + y | 0), 1876250);
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 90, characters 7-14", Belt_List.eq(Belt_MutableSet.toList(v), Belt_List.makeBy(1501, i => i + 500 | 0), (x, y) => x === y));
-    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 91, characters 7-14", Belt_MutableSet.toArray(v), Array_data_util.range(500, 2000));
+    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 87, characters 7-14", Belt_MutableSet.reduce(v, 0, (x, y) => x + y | 0), 1876250);
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 88, characters 7-14", Belt_List.eq(Belt_MutableSet.toList(v), Belt_List.makeBy(1501, i => i + 500 | 0), (x, y) => x === y));
+    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 89, characters 7-14", Belt_MutableSet.toArray(v), Array_data_util.range(500, 2000));
     Belt_MutableSet.checkInvariantInternal(v);
-    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 93, characters 7-14", Belt_MutableSet.get(v, 3), undefined);
-    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 94, characters 7-14", Belt_MutableSet.get(v, 1200), 1200);
+    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 91, characters 7-14", Belt_MutableSet.get(v, 3), undefined);
+    Test_utils.eq("File \"bs_poly_mutable_set_test.res\", line 92, characters 7-14", Belt_MutableSet.get(v, 1200), 1200);
     let match = Belt_MutableSet.split(v, 1000);
     let match$1 = match[0];
     let bb = match$1[1];
     let aa = match$1[0];
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 96, characters 7-14", match[1]);
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 97, characters 7-14", Belt_Array.eq(Belt_MutableSet.toArray(aa), Array_data_util.range(500, 999), (x, y) => x === y));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 98, characters 7-14", Belt_Array.eq(Belt_MutableSet.toArray(bb), Array_data_util.range(1001, 2000), (x, y) => x === y));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 99, characters 7-14", Belt_MutableSet.subset(aa, v));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 100, characters 7-14", Belt_MutableSet.subset(bb, v));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 101, characters 7-14", Belt_MutableSet.isEmpty(Belt_MutableSet.intersect(aa, bb)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 94, characters 7-14", match[1]);
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 95, characters 7-14", Belt_Array.eq(Belt_MutableSet.toArray(aa), Array_data_util.range(500, 999), (x, y) => x === y));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 96, characters 7-14", Belt_Array.eq(Belt_MutableSet.toArray(bb), Array_data_util.range(1001, 2000), (x, y) => x === y));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 97, characters 7-14", Belt_MutableSet.subset(aa, v));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 98, characters 7-14", Belt_MutableSet.subset(bb, v));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 99, characters 7-14", Belt_MutableSet.isEmpty(Belt_MutableSet.intersect(aa, bb)));
     let c = Belt_MutableSet.removeCheck(v, 1000);
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 103, characters 7-14", c);
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 101, characters 7-14", c);
     let match$2 = Belt_MutableSet.split(v, 1000);
     let match$3 = match$2[0];
     let bb$1 = match$3[1];
     let aa$1 = match$3[0];
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 105, characters 7-14", !match$2[1]);
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 106, characters 7-14", Belt_Array.eq(Belt_MutableSet.toArray(aa$1), Array_data_util.range(500, 999), (x, y) => x === y));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 107, characters 7-14", Belt_Array.eq(Belt_MutableSet.toArray(bb$1), Array_data_util.range(1001, 2000), (x, y) => x === y));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 108, characters 7-14", Belt_MutableSet.subset(aa$1, v));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 109, characters 7-14", Belt_MutableSet.subset(bb$1, v));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 110, characters 7-14", Belt_MutableSet.isEmpty(Belt_MutableSet.intersect(aa$1, bb$1)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 103, characters 7-14", !match$2[1]);
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 104, characters 7-14", Belt_Array.eq(Belt_MutableSet.toArray(aa$1), Array_data_util.range(500, 999), (x, y) => x === y));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 105, characters 7-14", Belt_Array.eq(Belt_MutableSet.toArray(bb$1), Array_data_util.range(1001, 2000), (x, y) => x === y));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 106, characters 7-14", Belt_MutableSet.subset(aa$1, v));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 107, characters 7-14", Belt_MutableSet.subset(bb$1, v));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 108, characters 7-14", Belt_MutableSet.isEmpty(Belt_MutableSet.intersect(aa$1, bb$1)));
   });
   Mocha.test("mutable set union and intersection operations", () => {
     let aa = Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 100), IntCmp);
     let bb = Belt_MutableSet.fromArray(Array_data_util.randomRange(40, 120), IntCmp);
     let cc = Belt_MutableSet.union(aa, bb);
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 120, characters 7-14", Belt_MutableSet.eq(cc, Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 120), IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 123, characters 6-13", Belt_MutableSet.eq(Belt_MutableSet.union(Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp)), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 40), IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 118, characters 7-14", Belt_MutableSet.eq(cc, Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 120), IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 121, characters 6-13", Belt_MutableSet.eq(Belt_MutableSet.union(Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp)), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 40), IntCmp)));
     let dd = Belt_MutableSet.intersect(aa, bb);
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 127, characters 7-14", Belt_MutableSet.eq(dd, Belt_MutableSet.fromArray(Array_data_util.randomRange(40, 100), IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 128, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.intersect(Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp)), Belt_MutableSet.make(IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 129, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.intersect(Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp)), Belt_MutableSet.make(IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 130, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.intersect(Belt_MutableSet.fromArray([
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 125, characters 7-14", Belt_MutableSet.eq(dd, Belt_MutableSet.fromArray(Array_data_util.randomRange(40, 100), IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 126, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.intersect(Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp)), Belt_MutableSet.make(IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 127, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.intersect(Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp)), Belt_MutableSet.make(IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 128, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.intersect(Belt_MutableSet.fromArray([
       1,
       3,
       4,
@@ -146,11 +144,11 @@ Mocha.describe("Bs_poly_mutable_set_test", () => {
       4,
       5
     ], IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 131, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.diff(aa, bb), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 39), IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 132, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.diff(bb, aa), Belt_MutableSet.fromArray(Array_data_util.randomRange(101, 120), IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 134, characters 6-13", Belt_MutableSet.eq(Belt_MutableSet.diff(Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp)), Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 138, characters 6-13", Belt_MutableSet.eq(Belt_MutableSet.diff(Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp)), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp)));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 143, characters 6-13", Belt_MutableSet.eq(Belt_MutableSet.diff(Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 40), IntCmp)), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, -1), IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 129, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.diff(aa, bb), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 39), IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 130, characters 7-14", Belt_MutableSet.eq(Belt_MutableSet.diff(bb, aa), Belt_MutableSet.fromArray(Array_data_util.randomRange(101, 120), IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 132, characters 6-13", Belt_MutableSet.eq(Belt_MutableSet.diff(Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp)), Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 136, characters 6-13", Belt_MutableSet.eq(Belt_MutableSet.diff(Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(21, 40), IntCmp)), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp)));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 141, characters 6-13", Belt_MutableSet.eq(Belt_MutableSet.diff(Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 20), IntCmp), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 40), IntCmp)), Belt_MutableSet.fromArray(Array_data_util.randomRange(0, -1), IntCmp)));
   });
   Mocha.test("mutable set keep and partition operations", () => {
     let a0 = Belt_MutableSet.fromArray(Array_data_util.randomRange(0, 1000), IntCmp);
@@ -159,8 +157,8 @@ Mocha.describe("Bs_poly_mutable_set_test", () => {
     let match = Belt_MutableSet.partition(a0, x => x % 2 === 0);
     let a4 = match[1];
     let a3 = match[0];
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 152, characters 7-14", Belt_MutableSet.eq(a1, a3));
-    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 153, characters 7-14", Belt_MutableSet.eq(a2, a4));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 150, characters 7-14", Belt_MutableSet.eq(a1, a3));
+    Test_utils.ok("File \"bs_poly_mutable_set_test.res\", line 151, characters 7-14", Belt_MutableSet.eq(a2, a4));
     Belt_List.forEach({
       hd: a0,
       tl: {
diff --git a/tests/tests/src/bs_poly_mutable_set_test.res b/tests/tests/src/bs_poly_mutable_set_test.res
index d843e0f25c6..dc929290c39 100644
--- a/tests/tests/src/bs_poly_mutable_set_test.res
+++ b/tests/tests/src/bs_poly_mutable_set_test.res
@@ -18,8 +18,8 @@ describe(__MODULE__, () => {
     ok(__LOC__, N.removeCheck(u, 20))
     eq(__LOC__, N.size(u), 28)
     let r = I.randomRange(0, 30)
-    ok(__LOC__, Js.eqUndefined(29, N.maxUndefined(u)))
-    ok(__LOC__, Js.eqUndefined(1, N.minUndefined(u)))
+    eq(__LOC__, N.maximum(u), Some(29))
+    eq(__LOC__, N.minimum(u), Some(1))
     N.add(u, 3)
     for i in 0 to A.length(r) - 1 {
       N.remove(u, A.getUnsafe(r, i))
@@ -84,8 +84,6 @@ describe(__MODULE__, () => {
     ok(__LOC__, N.isEmpty(empty()))
     eq(__LOC__, N.minimum(v), Some(500))
     eq(__LOC__, N.maximum(v), Some(2000))
-    eq(__LOC__, N.minUndefined(v), Js.Undefined.return(500))
-    eq(__LOC__, N.maxUndefined(v), Js.Undefined.return(2000))
     eq(__LOC__, N.reduce(v, 0, (x, y) => x + y), (500 + 2000) / 2 * 1501)
     ok(__LOC__, L.eq(N.toList(v), L.makeBy(1_501, i => i + 500), (x, y) => x == y))
     eq(__LOC__, N.toArray(v), I.range(500, 2000))
diff --git a/tests/tests/src/bs_poly_set_test.mjs b/tests/tests/src/bs_poly_set_test.mjs
index 1a64ff282b0..764f7b0fe0c 100644
--- a/tests/tests/src/bs_poly_set_test.mjs
+++ b/tests/tests/src/bs_poly_set_test.mjs
@@ -73,8 +73,8 @@ Mocha.describe("Bs_poly_set_test", () => {
     Test_utils.ok("File \"bs_poly_set_test.res\", line 45, characters 7-14", u0 !== u1);
     Test_utils.ok("File \"bs_poly_set_test.res\", line 46, characters 7-14", u2 === u1);
     Test_utils.eq("File \"bs_poly_set_test.res\", line 47, characters 7-14", Belt_Set.size(u4), 28);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 48, characters 7-14", 29 === Belt_Set.maxUndefined(u4));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 49, characters 7-14", 1 === Belt_Set.minUndefined(u4));
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 48, characters 7-14", Belt_Set.maximum(u4), 29);
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 49, characters 7-14", Belt_Set.minimum(u4), 1);
     Test_utils.ok("File \"bs_poly_set_test.res\", line 50, characters 7-14", u4 === u5);
     Test_utils.ok("File \"bs_poly_set_test.res\", line 51, characters 7-14", Belt_Set.isEmpty(u6));
     Test_utils.eq("File \"bs_poly_set_test.res\", line 52, characters 7-14", Belt_Set.size(u7), 3);
@@ -118,35 +118,31 @@ Mocha.describe("Bs_poly_set_test", () => {
     Test_utils.ok("File \"bs_poly_set_test.res\", line 90, characters 7-14", !Belt_Set.subset(u18, u23));
     Test_utils.ok("File \"bs_poly_set_test.res\", line 91, characters 7-14", Belt_Set.subset(u22, u17));
     Test_utils.ok("File \"bs_poly_set_test.res\", line 92, characters 7-14", Belt_Set.subset(u21, u17) && Belt_Set.subset(u21, u18));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 93, characters 7-14", 47 === Belt_Set.getUndefined(u22, 47));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 94, characters 7-14", Primitive_object.equal(47, Belt_Set.get(u22, 47)));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 95, characters 7-14", Belt_Set.getUndefined(u22, 59) === undefined);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 96, characters 7-14", undefined === Belt_Set.get(u22, 59));
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 98, characters 7-14", Belt_Set.size(u25), 60);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 99, characters 7-14", Belt_Set.minimum(Belt_Set.make(IntCmp)) === undefined);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 100, characters 7-14", Belt_Set.maximum(Belt_Set.make(IntCmp)) === undefined);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 101, characters 7-14", Belt_Set.minUndefined(Belt_Set.make(IntCmp)) === undefined);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 102, characters 7-14", Belt_Set.maxUndefined(Belt_Set.make(IntCmp)) === undefined);
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 93, characters 7-14", Primitive_object.equal(47, Belt_Set.get(u22, 47)));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 94, characters 7-14", undefined === Belt_Set.get(u22, 59));
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 96, characters 7-14", Belt_Set.size(u25), 60);
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 97, characters 7-14", Belt_Set.minimum(Belt_Set.make(IntCmp)) === undefined);
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 98, characters 7-14", Belt_Set.maximum(Belt_Set.make(IntCmp)) === undefined);
   });
   Mocha.test("set iteration and comparison operations", () => {
     let u0 = Belt_Set.fromArray(Array_data_util.randomRange(0, 20), IntCmp);
     let u1 = Belt_Set.remove(u0, 17);
     let u2 = Belt_Set.add(u1, 33);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 109, characters 7-14", Belt_List.every2(testIterToList(u0), Belt_List.makeBy(21, i => i), (x, y) => x === y));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 110, characters 7-14", Belt_List.every2(testIterToList2(u0), Belt_List.makeBy(21, i => i), (x, y) => x === y));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 111, characters 7-14", Belt_List.every2(testIterToList(u0), Belt_Set.toList(u0), (x, y) => x === y));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 112, characters 7-14", Belt_Set.some(u0, x => x === 17));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 113, characters 7-14", !Belt_Set.some(u1, x => x === 17));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 114, characters 7-14", Belt_Set.every(u0, x => x < 24));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 115, characters 7-14", Belt_SetDict.every(Belt_Set.getData(u0), x => x < 24));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 116, characters 7-14", !Belt_Set.every(u2, x => x < 24));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 117, characters 7-14", !Belt_Set.every(Belt_Set.fromArray([
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 105, characters 7-14", Belt_List.every2(testIterToList(u0), Belt_List.makeBy(21, i => i), (x, y) => x === y));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 106, characters 7-14", Belt_List.every2(testIterToList2(u0), Belt_List.makeBy(21, i => i), (x, y) => x === y));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 107, characters 7-14", Belt_List.every2(testIterToList(u0), Belt_Set.toList(u0), (x, y) => x === y));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 108, characters 7-14", Belt_Set.some(u0, x => x === 17));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 109, characters 7-14", !Belt_Set.some(u1, x => x === 17));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 110, characters 7-14", Belt_Set.every(u0, x => x < 24));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 111, characters 7-14", Belt_SetDict.every(Belt_Set.getData(u0), x => x < 24));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 112, characters 7-14", !Belt_Set.every(u2, x => x < 24));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 113, characters 7-14", !Belt_Set.every(Belt_Set.fromArray([
       1,
       2,
       3
     ], IntCmp), x => x === 2));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 118, characters 7-14", Belt_Set.cmp(u1, u0) < 0);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 119, characters 7-14", Belt_Set.cmp(u0, u1) > 0);
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 114, characters 7-14", Belt_Set.cmp(u1, u0) < 0);
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 115, characters 7-14", Belt_Set.cmp(u0, u1) > 0);
   });
   Mocha.test("set keep and partition operations", () => {
     let a0 = Belt_Set.fromArray(Array_data_util.randomRange(0, 1000), IntCmp);
@@ -155,33 +151,33 @@ Mocha.describe("Bs_poly_set_test", () => {
     let match = Belt_Set.partition(a0, x => x % 2 === 0);
     let a4 = match[1];
     let a3 = match[0];
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 126, characters 7-14", Belt_Set.eq(a1, a3));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 127, characters 7-14", Belt_Set.eq(a2, a4));
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 128, characters 7-14", Belt_Set.getExn(a0, 3), 3);
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 129, characters 7-14", Belt_Set.getExn(a0, 4), 4);
-    Test_utils.throws("File \"bs_poly_set_test.res\", line 130, characters 11-18", () => {
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 122, characters 7-14", Belt_Set.eq(a1, a3));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 123, characters 7-14", Belt_Set.eq(a2, a4));
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 124, characters 7-14", Belt_Set.getExn(a0, 3), 3);
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 125, characters 7-14", Belt_Set.getExn(a0, 4), 4);
+    Test_utils.throws("File \"bs_poly_set_test.res\", line 126, characters 11-18", () => {
       Belt_Set.getExn(a0, 1002);
     });
-    Test_utils.throws("File \"bs_poly_set_test.res\", line 131, characters 11-18", () => {
+    Test_utils.throws("File \"bs_poly_set_test.res\", line 127, characters 11-18", () => {
       Belt_Set.getExn(a0, -1);
     });
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 132, characters 7-14", Belt_Set.size(a0), 1001);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 133, characters 7-14", !Belt_Set.isEmpty(a0));
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 128, characters 7-14", Belt_Set.size(a0), 1001);
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 129, characters 7-14", !Belt_Set.isEmpty(a0));
     let match$1 = Belt_Set.split(a0, 200);
     let match$2 = match$1[0];
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 135, characters 7-14", match$1[1]);
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 136, characters 7-14", Belt_Set.toArray(match$2[0]), Belt_Array.makeBy(200, i => i));
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 137, characters 7-14", Belt_Set.toList(match$2[1]), Belt_List.makeBy(800, i => i + 201 | 0));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 131, characters 7-14", match$1[1]);
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 132, characters 7-14", Belt_Set.toArray(match$2[0]), Belt_Array.makeBy(200, i => i));
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 133, characters 7-14", Belt_Set.toList(match$2[1]), Belt_List.makeBy(800, i => i + 201 | 0));
     let a7 = Belt_Set.remove(a0, 200);
     let match$3 = Belt_Set.split(a7, 200);
     let match$4 = match$3[0];
     let a9 = match$4[1];
     let a8 = match$4[0];
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 140, characters 7-14", !match$3[1]);
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 141, characters 7-14", Belt_Set.toArray(a8), Belt_Array.makeBy(200, i => i));
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 142, characters 7-14", Belt_Set.toList(a9), Belt_List.makeBy(800, i => i + 201 | 0));
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 143, characters 7-14", Belt_Set.minimum(a8), 0);
-    Test_utils.eq("File \"bs_poly_set_test.res\", line 144, characters 7-14", Belt_Set.minimum(a9), 201);
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 136, characters 7-14", !match$3[1]);
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 137, characters 7-14", Belt_Set.toArray(a8), Belt_Array.makeBy(200, i => i));
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 138, characters 7-14", Belt_Set.toList(a9), Belt_List.makeBy(800, i => i + 201 | 0));
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 139, characters 7-14", Belt_Set.minimum(a8), 0);
+    Test_utils.eq("File \"bs_poly_set_test.res\", line 140, characters 7-14", Belt_Set.minimum(a9), 201);
     Belt_List.forEach({
       hd: a0,
       tl: {
@@ -201,14 +197,14 @@ Mocha.describe("Bs_poly_set_test", () => {
   });
   Mocha.test("empty set operations", () => {
     let a = Belt_Set.fromArray([], IntCmp);
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 150, characters 7-14", Belt_Set.isEmpty(Belt_Set.keep(a, x => x % 2 === 0)));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 146, characters 7-14", Belt_Set.isEmpty(Belt_Set.keep(a, x => x % 2 === 0)));
   });
   Mocha.test("split empty set operations", () => {
     let match = Belt_Set.split(Belt_Set.make(IntCmp), 0);
     let match$1 = match[0];
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 155, characters 7-14", Belt_Set.isEmpty(match$1[0]));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 156, characters 7-14", Belt_Set.isEmpty(match$1[1]));
-    Test_utils.ok("File \"bs_poly_set_test.res\", line 157, characters 7-14", !match[1]);
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 151, characters 7-14", Belt_Set.isEmpty(match$1[0]));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 152, characters 7-14", Belt_Set.isEmpty(match$1[1]));
+    Test_utils.ok("File \"bs_poly_set_test.res\", line 153, characters 7-14", !match[1]);
   });
 });
 
diff --git a/tests/tests/src/bs_poly_set_test.res b/tests/tests/src/bs_poly_set_test.res
index 91b33735360..af6c7022c63 100644
--- a/tests/tests/src/bs_poly_set_test.res
+++ b/tests/tests/src/bs_poly_set_test.res
@@ -45,8 +45,8 @@ describe(__MODULE__, () => {
     ok(__LOC__, u0 !== u1)
     ok(__LOC__, u2 === u1)
     eq(__LOC__, N.size(u4), 28)
-    ok(__LOC__, Js.eqUndefined(29, N.maxUndefined(u4)))
-    ok(__LOC__, Js.eqUndefined(1, N.minUndefined(u4)))
+    eq(__LOC__, N.maximum(u4), Some(29))
+    eq(__LOC__, N.minimum(u4), Some(1))
     ok(__LOC__, u4 === u5)
     ok(__LOC__, N.isEmpty(u6))
     eq(__LOC__, N.size(u7), 3)
@@ -90,16 +90,12 @@ describe(__MODULE__, () => {
     ok(__LOC__, !N.subset(u18, u23))
     ok(__LOC__, N.subset(u22, u17))
     ok(__LOC__, N.subset(u21, u17) && N.subset(u21, u18))
-    ok(__LOC__, Js.eqUndefined(47, N.getUndefined(u22, 47)))
     ok(__LOC__, Some(47) == N.get(u22, 47))
-    ok(__LOC__, N.getUndefined(u22, 59) == Js.undefined)
     ok(__LOC__, None == N.get(u22, 59))
 
     eq(__LOC__, N.size(u25), 60)
     ok(__LOC__, N.minimum(N.make(~id=module(IntCmp))) == None)
     ok(__LOC__, N.maximum(N.make(~id=module(IntCmp))) == None)
-    ok(__LOC__, N.minUndefined(N.make(~id=module(IntCmp))) == Js.undefined)
-    ok(__LOC__, N.maxUndefined(N.make(~id=module(IntCmp))) == Js.undefined)
   })
 
   test("set iteration and comparison operations", () => {
diff --git a/tests/tests/src/bs_set_int_test.mjs b/tests/tests/src/bs_set_int_test.mjs
index bb87436f781..2bf1b07cc64 100644
--- a/tests/tests/src/bs_set_int_test.mjs
+++ b/tests/tests/src/bs_set_int_test.mjs
@@ -99,60 +99,59 @@ Mocha.describe("Bs_set_int_test", () => {
       33,
       -1
     ]);
-    let minv = Belt_SetInt.minUndefined(v$1);
-    let maxv = Belt_SetInt.maxUndefined(v$1);
-    let approx = (loc, x, y) => Test_utils.ok(loc, x === y);
-    Test_utils.eq("File \"bs_set_int_test.res\", line 113, characters 7-14", Belt_SetInt.reduce(v$1, 0, (x, y) => x + y | 0), Belt_Array.reduce(ss, 0, (a, b) => a + b | 0));
-    approx("File \"bs_set_int_test.res\", line 114, characters 11-18", -1, minv);
-    approx("File \"bs_set_int_test.res\", line 115, characters 11-18", 222, maxv);
+    let minv = Belt_SetInt.minimum(v$1);
+    let maxv = Belt_SetInt.maximum(v$1);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 112, characters 7-14", Belt_SetInt.reduce(v$1, 0, (x, y) => x + y | 0), Belt_Array.reduce(ss, 0, (a, b) => a + b | 0));
+    Test_utils.eq("File \"bs_set_int_test.res\", line 113, characters 7-14", minv, -1);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 114, characters 7-14", maxv, 222);
     let v$2 = Belt_SetInt.remove(v$1, 3);
     let minv$1 = Belt_SetInt.minimum(v$2);
     let maxv$1 = Belt_SetInt.maximum(v$2);
-    Test_utils.eq("File \"bs_set_int_test.res\", line 118, characters 7-14", minv$1, -1);
-    Test_utils.eq("File \"bs_set_int_test.res\", line 119, characters 7-14", maxv$1, 222);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 117, characters 7-14", minv$1, -1);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 118, characters 7-14", maxv$1, 222);
     let v$3 = Belt_SetInt.remove(v$2, 222);
     let minv$2 = Belt_SetInt.minimum(v$3);
     let maxv$2 = Belt_SetInt.maximum(v$3);
-    Test_utils.eq("File \"bs_set_int_test.res\", line 122, characters 7-14", minv$2, -1);
-    Test_utils.eq("File \"bs_set_int_test.res\", line 123, characters 7-14", maxv$2, 33);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 121, characters 7-14", minv$2, -1);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 122, characters 7-14", maxv$2, 33);
     let v$4 = Belt_SetInt.remove(v$3, -1);
     let minv$3 = Belt_SetInt.minimum(v$4);
     let maxv$3 = Belt_SetInt.maximum(v$4);
-    Test_utils.eq("File \"bs_set_int_test.res\", line 126, characters 7-14", minv$3, 0);
-    Test_utils.eq("File \"bs_set_int_test.res\", line 127, characters 7-14", maxv$3, 33);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 125, characters 7-14", minv$3, 0);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 126, characters 7-14", maxv$3, 33);
     let v$5 = Belt_SetInt.remove(v$4, 0);
     let v$6 = Belt_SetInt.remove(v$5, 33);
     let v$7 = Belt_SetInt.remove(v$6, 2);
     let v$8 = Belt_SetInt.remove(v$7, 3);
     let v$9 = Belt_SetInt.remove(v$8, 4);
     let v$10 = Belt_SetInt.remove(v$9, 1);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 134, characters 7-14", Belt_SetInt.isEmpty(v$10));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 133, characters 7-14", Belt_SetInt.isEmpty(v$10));
     let v$11 = Belt_Array.makeByAndShuffle(1000000, i => i);
     let u$1 = Belt_SetInt.fromArray(v$11);
     Belt_SetInt.checkInvariantInternal(u$1);
     let firstHalf = Belt_Array.slice(v$11, 0, 2000);
     let xx = Belt_Array.reduce(firstHalf, u$1, Belt_SetInt.remove);
     Belt_SetInt.checkInvariantInternal(u$1);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 144, characters 6-13", Belt_SetInt.eq(Belt_SetInt.union(Belt_SetInt.fromArray(firstHalf), xx), u$1));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 143, characters 6-13", Belt_SetInt.eq(Belt_SetInt.union(Belt_SetInt.fromArray(firstHalf), xx), u$1));
     let aa = Belt_SetInt.fromArray(Array_data_util.randomRange(0, 100));
     let bb = Belt_SetInt.fromArray(Array_data_util.randomRange(0, 200));
     let cc = Belt_SetInt.fromArray(Array_data_util.randomRange(120, 200));
     let dd = Belt_SetInt.union(aa, cc);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 155, characters 7-14", Belt_SetInt.subset(aa, bb));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 156, characters 7-14", Belt_SetInt.subset(dd, bb));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 157, characters 7-14", Belt_SetInt.subset(Belt_SetInt.add(dd, 200), bb));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 158, characters 7-14", Belt_SetInt.add(dd, 200) === dd);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 159, characters 7-14", Belt_SetInt.add(dd, 0) === dd);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 160, characters 7-14", !Belt_SetInt.subset(Belt_SetInt.add(dd, 201), bb));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 154, characters 7-14", Belt_SetInt.subset(aa, bb));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 155, characters 7-14", Belt_SetInt.subset(dd, bb));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 156, characters 7-14", Belt_SetInt.subset(Belt_SetInt.add(dd, 200), bb));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 157, characters 7-14", Belt_SetInt.add(dd, 200) === dd);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 158, characters 7-14", Belt_SetInt.add(dd, 0) === dd);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 159, characters 7-14", !Belt_SetInt.subset(Belt_SetInt.add(dd, 201), bb));
     let aa$1 = Belt_SetInt.fromArray(Array_data_util.randomRange(0, 100));
     let bb$1 = Belt_SetInt.fromArray(Array_data_util.randomRange(0, 100));
     let cc$1 = Belt_SetInt.add(bb$1, 101);
     let dd$1 = Belt_SetInt.remove(bb$1, 99);
     let ee = Belt_SetInt.add(dd$1, 101);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 167, characters 7-14", Belt_SetInt.eq(aa$1, bb$1));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 168, characters 7-14", !Belt_SetInt.eq(aa$1, cc$1));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 169, characters 7-14", !Belt_SetInt.eq(dd$1, cc$1));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 170, characters 7-14", !Belt_SetInt.eq(bb$1, ee));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 166, characters 7-14", Belt_SetInt.eq(aa$1, bb$1));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 167, characters 7-14", !Belt_SetInt.eq(aa$1, cc$1));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 168, characters 7-14", !Belt_SetInt.eq(dd$1, cc$1));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 169, characters 7-14", !Belt_SetInt.eq(bb$1, ee));
     let a1 = Belt_SetInt.mergeMany(undefined, Array_data_util.randomRange(0, 100));
     let a2 = Belt_SetInt.removeMany(a1, Array_data_util.randomRange(40, 100));
     let a3 = Belt_SetInt.fromArray(Array_data_util.randomRange(0, 39));
@@ -160,28 +159,28 @@ Mocha.describe("Bs_set_int_test", () => {
     let match$2 = match$1[0];
     let a5 = match$2[1];
     let a4 = match$2[0];
-    Test_utils.ok("File \"bs_set_int_test.res\", line 177, characters 7-14", Belt_SetInt.eq(a1, Belt_SetInt.fromArray(Array_data_util.randomRange(0, 100))));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 178, characters 7-14", Belt_SetInt.eq(a2, a3));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 179, characters 7-14", match$1[1]);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 180, characters 7-14", Belt_SetInt.eq(a3, a4));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 176, characters 7-14", Belt_SetInt.eq(a1, Belt_SetInt.fromArray(Array_data_util.randomRange(0, 100))));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 177, characters 7-14", Belt_SetInt.eq(a2, a3));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 178, characters 7-14", match$1[1]);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 179, characters 7-14", Belt_SetInt.eq(a3, a4));
     let a6 = Belt_SetInt.remove(Belt_SetInt.removeMany(a1, Array_data_util.randomRange(0, 39)), 40);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 182, characters 7-14", Belt_SetInt.eq(a5, a6));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 181, characters 7-14", Belt_SetInt.eq(a5, a6));
     let a7 = Belt_SetInt.remove(a1, 40);
     let match$3 = Belt_SetInt.split(a7, 40);
     let match$4 = match$3[0];
     let a9 = match$4[1];
-    Test_utils.ok("File \"bs_set_int_test.res\", line 185, characters 7-14", !match$3[1]);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 186, characters 7-14", Belt_SetInt.eq(a4, match$4[0]));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 187, characters 7-14", Belt_SetInt.eq(a5, a9));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 184, characters 7-14", !match$3[1]);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 185, characters 7-14", Belt_SetInt.eq(a4, match$4[0]));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 186, characters 7-14", Belt_SetInt.eq(a5, a9));
     let a10 = Belt_SetInt.removeMany(a9, Array_data_util.randomRange(42, 2000));
-    Test_utils.eq("File \"bs_set_int_test.res\", line 189, characters 7-14", Belt_SetInt.size(a10), 1);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 188, characters 7-14", Belt_SetInt.size(a10), 1);
     let a11 = Belt_SetInt.removeMany(a9, Array_data_util.randomRange(0, 2000));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 191, characters 7-14", Belt_SetInt.isEmpty(a11));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 190, characters 7-14", Belt_SetInt.isEmpty(a11));
     let match$5 = Belt_SetInt.split(undefined, 0);
     let match$6 = match$5[0];
-    Test_utils.ok("File \"bs_set_int_test.res\", line 194, characters 7-14", Belt_SetInt.isEmpty(match$6[0]));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 195, characters 7-14", Belt_SetInt.isEmpty(match$6[1]));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 196, characters 7-14", !match$5[1]);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 193, characters 7-14", Belt_SetInt.isEmpty(match$6[0]));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 194, characters 7-14", Belt_SetInt.isEmpty(match$6[1]));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 195, characters 7-14", !match$5[1]);
     let v$12 = Belt_SetInt.fromArray(Array_data_util.randomRange(0, 2000));
     let v0 = Belt_SetInt.fromArray(Array_data_util.randomRange(0, 2000));
     let v1 = Belt_SetInt.fromArray(Array_data_util.randomRange(1, 2001));
@@ -198,15 +197,15 @@ Mocha.describe("Bs_set_int_test", () => {
         return acc;
       }
     });
-    Test_utils.eq("File \"bs_set_int_test.res\", line 214, characters 7-14", counted, 1001);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 215, characters 7-14", Belt_SetInt.eq(v$12, v0));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 216, characters 7-14", Belt_SetInt.cmp(v$12, v0) === 0);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 217, characters 7-14", Belt_SetInt.cmp(v$12, v1) < 0);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 218, characters 7-14", Belt_SetInt.cmp(v$12, v2) > 0);
-    Test_utils.ok("File \"bs_set_int_test.res\", line 219, characters 7-14", Belt_SetInt.subset(v3, v0));
-    Test_utils.ok("File \"bs_set_int_test.res\", line 220, characters 7-14", !Belt_SetInt.subset(v1, v0));
-    Test_utils.eq("File \"bs_set_int_test.res\", line 221, characters 7-14", Belt_SetInt.get(v$12, 30), 30);
-    Test_utils.eq("File \"bs_set_int_test.res\", line 222, characters 7-14", Belt_SetInt.get(v$12, 3000), undefined);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 213, characters 7-14", counted, 1001);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 214, characters 7-14", Belt_SetInt.eq(v$12, v0));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 215, characters 7-14", Belt_SetInt.cmp(v$12, v0) === 0);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 216, characters 7-14", Belt_SetInt.cmp(v$12, v1) < 0);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 217, characters 7-14", Belt_SetInt.cmp(v$12, v2) > 0);
+    Test_utils.ok("File \"bs_set_int_test.res\", line 218, characters 7-14", Belt_SetInt.subset(v3, v0));
+    Test_utils.ok("File \"bs_set_int_test.res\", line 219, characters 7-14", !Belt_SetInt.subset(v1, v0));
+    Test_utils.eq("File \"bs_set_int_test.res\", line 220, characters 7-14", Belt_SetInt.get(v$12, 30), 30);
+    Test_utils.eq("File \"bs_set_int_test.res\", line 221, characters 7-14", Belt_SetInt.get(v$12, 3000), undefined);
   });
 });
 
diff --git a/tests/tests/src/bs_set_int_test.res b/tests/tests/src/bs_set_int_test.res
index 4503e8752a0..9bfd9e12f33 100644
--- a/tests/tests/src/bs_set_int_test.res
+++ b/tests/tests/src/bs_set_int_test.res
@@ -108,11 +108,10 @@ describe(__MODULE__, () => {
 
     let ss = [1, 222, 3, 4, 2, 0, 33, -1]
     let v = ofA([1, 222, 3, 4, 2, 0, 33, -1])
-    let (minv, maxv) = (N.minUndefined(v), N.maxUndefined(v))
-    let approx = (loc, x: int, y) => ok(loc, Js.eqUndefined(x, y))
+    let (minv, maxv) = (N.minimum(v), N.maximum(v))
     eq(__LOC__, N.reduce(v, 0, (x, y) => x + y), A.reduce(ss, 0, (a, b) => a + b))
-    approx(__LOC__, -1, minv)
-    approx(__LOC__, 222, maxv)
+    eq(__LOC__, minv, Some(-1))
+    eq(__LOC__, maxv, Some(222))
     let v = N.remove(v, 3)
     let (minv, maxv) = (N.minimum(v), N.maximum(v))
     eq(__LOC__, minv, Some(-1))
diff --git a/tests/tests/src/bs_stack_test.mjs b/tests/tests/src/bs_stack_test.mjs
index e565d4b515b..cfcd9809de1 100644
--- a/tests/tests/src/bs_stack_test.mjs
+++ b/tests/tests/src/bs_stack_test.mjs
@@ -17,7 +17,7 @@ function inOrder(v) {
     current = v$1.left;
   };
   while (!Belt_MutableStack.isEmpty(s)) {
-    current = Belt_MutableStack.popUndefined(s);
+    current = Belt_MutableStack.popOrThrow(s);
     let v$2 = current;
     Belt_MutableQueue.add(q, v$2.value);
     current = v$2.right;
@@ -64,7 +64,7 @@ function inOrder2(v) {
     } else if (Belt_MutableStack.isEmpty(s)) {
       todo = false;
     } else {
-      cursor = Belt_MutableStack.popUndefined(s);
+      cursor = Belt_MutableStack.popOrThrow(s);
       let current = cursor;
       Belt_MutableQueue.add(q, current.value);
       cursor = current.right;
diff --git a/tests/tests/src/bs_stack_test.res b/tests/tests/src/bs_stack_test.res
index fd14dcae46d..2915ce64486 100644
--- a/tests/tests/src/bs_stack_test.res
+++ b/tests/tests/src/bs_stack_test.res
@@ -21,7 +21,7 @@ let inOrder = (v: t): array<int> => {
     current := leftGet(v)
   }
   while !S.isEmpty(s) {
-    current := S.popUndefined(s)
+    current := Js.Undefined.return(S.popOrThrow(s))
     let v = Js.Undefined.getUnsafe(current.contents)
     Q.add(q, valueGet(v))
     current := rightGet(v)
@@ -66,7 +66,7 @@ let inOrder2 = (v: t) => {
       S.push(s, v)
       cursor := leftGet(v)
     } else if !S.isEmpty(s) {
-      cursor := S.popUndefined(s)
+      cursor := Js.Undefined.return(S.popOrThrow(s))
       let current = Js.Undefined.getUnsafe(cursor.contents)
       Q.add(q, valueGet(current))
       cursor := rightGet(current)