Port Belt.Array's zip, zipBy, partition, unzip to Stdlib Array (#8244)

* Port Belt.Array's zip, zipBy, partition, unzip to Stdlib Array

* Update completion test

* Update CHANGELOG

* Missed the PR link
# Conflicts:
#	packages/@rescript/runtime/lib/es6/Stdlib_Array.js
#	packages/@rescript/runtime/lib/js/Stdlib_Array.js

Author: shulhi

CHANGELOG.md

@@ -14,6 +14,8 @@
 
 #### :boom: Breaking Change
 
+- Stdlib: Added Array.zip, Array.unzip, Array.zipBy, and Array.partition. https://github.com/rescript-lang/rescript/pull/8244
+
 #### :eyeglasses: Spec Compliance
 
 #### :rocket: New Feature

packages/@rescript/runtime/Stdlib_Array.res

@@ -346,6 +346,59 @@ let findMap = (arr, f) => {
   loop(0)
 }
 
+let zip = (xs, ys) => {
+  let (lenx, leny) = (length(xs), length(ys))
+  let len = min(lenx, leny)
+  let s = makeUninitializedUnsafe(len)
+  for i in 0 to len - 1 {
+    setUnsafe(s, i, (getUnsafe(xs, i), getUnsafe(ys, i)))
+  }
+  s
+}
+
+let zipBy = (xs, ys, f) => {
+  let (lenx, leny) = (length(xs), length(ys))
+  let len = min(lenx, leny)
+  let s = makeUninitializedUnsafe(len)
+  for i in 0 to len - 1 {
+    setUnsafe(s, i, f(getUnsafe(xs, i), getUnsafe(ys, i)))
+  }
+  s
+}
+
+let partition = (a, f) => {
+  let l = length(a)
+  let i = ref(0)
+  let j = ref(0)
+  let a1 = makeUninitializedUnsafe(l)
+  let a2 = makeUninitializedUnsafe(l)
+  for ii in 0 to l - 1 {
+    let v = getUnsafe(a, ii)
+    if f(v) {
+      setUnsafe(a1, i.contents, v)
+      i.contents = i.contents + 1
+    } else {
+      setUnsafe(a2, j.contents, v)
+      j.contents = j.contents + 1
+    }
+  }
+  truncateToLengthUnsafe(a1, i.contents)
+  truncateToLengthUnsafe(a2, j.contents)
+  (a1, a2)
+}
+
+let unzip = a => {
+  let l = length(a)
+  let a1 = makeUninitializedUnsafe(l)
+  let a2 = makeUninitializedUnsafe(l)
+  for i in 0 to l - 1 {
+    let (v1, v2) = getUnsafe(a, i)
+    setUnsafe(a1, i, v1)
+    setUnsafe(a2, i, v2)
+  }
+  (a1, a2)
+}
+
 @send external at: (array<'a>, int) => option<'a> = "at"
 
 let last = a => a->get(a->length - 1)

packages/@rescript/runtime/Stdlib_Array.resi

@@ -1555,6 +1555,61 @@ Array.findMap([], n => mod(n, 2) == 0 ? Some(n * n) : None) == None
 */
 let findMap: (array<'a>, 'a => option<'b>) => option<'b>
 
+/**
+`zip(a, b)` create an array of pairs from corresponding elements of a and b.
+Stop with the shorter array.
+
+## Examples
+
+```rescript
+Array.zip([1, 2], [3, 4, 5]) == [(1, 3), (2, 4)]
+```
+*/
+let zip: (t<'a>, array<'b>) => array<('a, 'b)>
+
+/**
+`zipBy(xs, ys, f)` create an array by applying `f` to corresponding elements of
+`xs` and `ys`. Stops with shorter array.
+
+Equivalent to `map(zip(xs, ys), ((a, b)) => f(a, b))`
+
+## Examples
+
+```rescript
+Array.zipBy([1, 2, 3], [4, 5], (a, b) => 2 * a + b) == [6, 9]
+```
+*/
+let zipBy: (t<'a>, array<'b>, ('a, 'b) => 'c) => array<'c>
+
+/**
+`partition(f, a)` split array into tuple of two arrays based on predicate `f`;
+first of tuple where predicate cause true, second where predicate cause false
+
+## Examples
+
+```rescript
+Array.partition([1, 2, 3, 4, 5], x => mod(x, 2) == 0) == ([2, 4], [1, 3, 5])
+
+Array.partition([1, 2, 3, 4, 5], x => mod(x, 2) != 0) == ([1, 3, 5], [2, 4])
+```
+*/
+let partition: (t<'a>, 'a => bool) => (t<'a>, t<'a>)
+
+/**
+`unzip(a)` takes an array of pairs and creates a pair of arrays. The first array
+contains all the first items of the pairs; the second array contains all the
+second items.
+
+## Examples
+
+```rescript
+Array.unzip([(1, 2), (3, 4)]) == ([1, 3], [2, 4])
+
+Array.unzip([(1, 2), (3, 4), (5, 6), (7, 8)]) == ([1, 3, 5, 7], [2, 4, 6, 8])
+```
+*/
+let unzip: array<('a, 'b)> => (t<'a>, array<'b>)
+
 /**
 `at(array, index)`
 

packages/@rescript/runtime/lib/es6/Stdlib_Array.js

@@ -1,5 +1,6 @@
 
 
+import * as Primitive_int from "./Primitive_int.js";
 import * as Primitive_option from "./Primitive_option.js";
 
 function make(length, x) {
@@ -189,6 +190,70 @@ function findMap(arr, f) {
   };
 }
 
+function zip(xs, ys) {
+  let lenx = xs.length;
+  let leny = ys.length;
+  let len = Primitive_int.min(lenx, leny);
+  let s = new Array(len);
+  for (let i = 0; i < len; ++i) {
+    s[i] = [
+      xs[i],
+      ys[i]
+    ];
+  }
+  return s;
+}
+
+function zipBy(xs, ys, f) {
+  let lenx = xs.length;
+  let leny = ys.length;
+  let len = Primitive_int.min(lenx, leny);
+  let s = new Array(len);
+  for (let i = 0; i < len; ++i) {
+    s[i] = f(xs[i], ys[i]);
+  }
+  return s;
+}
+
+function partition(a, f) {
+  let l = a.length;
+  let i = 0;
+  let j = 0;
+  let a1 = new Array(l);
+  let a2 = new Array(l);
+  for (let ii = 0; ii < l; ++ii) {
+    let v = a[ii];
+    if (f(v)) {
+      a1[i] = v;
+      i = i + 1 | 0;
+    } else {
+      a2[j] = v;
+      j = j + 1 | 0;
+    }
+  }
+  a1.length = i;
+  a2.length = j;
+  return [
+    a1,
+    a2
+  ];
+}
+
+function unzip(a) {
+  let l = a.length;
+  let a1 = new Array(l);
+  let a2 = new Array(l);
+  for (let i = 0; i < l; ++i) {
+    let match = a[i];
+    a1[i] = match[0];
+    a2[i] = match[1];
+  }
+  return [
+    a1,
+    a2
+  ];
+}
+
 function last(a) {
   return a[a.length - 1 | 0];
 }
@@ -213,6 +278,10 @@ export {
   toShuffled,
   shuffle,
   findMap,
+  zip,
+  zipBy,
+  partition,
+  unzip,
   last,
 }
 /* No side effect */

packages/@rescript/runtime/lib/js/Stdlib_Array.js

@@ -1,5 +1,6 @@
 'use strict';
 
+let Primitive_int = require("./Primitive_int.js");
 let Primitive_option = require("./Primitive_option.js");
 
 function make(length, x) {
@@ -189,6 +190,70 @@ function findMap(arr, f) {
   };
 }
 
+function zip(xs, ys) {
+  let lenx = xs.length;
+  let leny = ys.length;
+  let len = Primitive_int.min(lenx, leny);
+  let s = new Array(len);
+  for (let i = 0; i < len; ++i) {
+    s[i] = [
+      xs[i],
+      ys[i]
+    ];
+  }
+  return s;
+}
+
+function zipBy(xs, ys, f) {
+  let lenx = xs.length;
+  let leny = ys.length;
+  let len = Primitive_int.min(lenx, leny);
+  let s = new Array(len);
+  for (let i = 0; i < len; ++i) {
+    s[i] = f(xs[i], ys[i]);
+  }
+  return s;
+}
+
+function partition(a, f) {
+  let l = a.length;
+  let i = 0;
+  let j = 0;
+  let a1 = new Array(l);
+  let a2 = new Array(l);
+  for (let ii = 0; ii < l; ++ii) {
+    let v = a[ii];
+    if (f(v)) {
+      a1[i] = v;
+      i = i + 1 | 0;
+    } else {
+      a2[j] = v;
+      j = j + 1 | 0;
+    }
+  }
+  a1.length = i;
+  a2.length = j;
+  return [
+    a1,
+    a2
+  ];
+}
+
+function unzip(a) {
+  let l = a.length;
+  let a1 = new Array(l);
+  let a2 = new Array(l);
+  for (let i = 0; i < l; ++i) {
+    let match = a[i];
+    a1[i] = match[0];
+    a2[i] = match[1];
+  }
+  return [
+    a1,
+    a2
+  ];
+}
+
 function last(a) {
   return a[a.length - 1 | 0];
 }
@@ -212,5 +277,9 @@ exports.keepSome = keepSome;
 exports.toShuffled = toShuffled;
 exports.shuffle = shuffle;
 exports.findMap = findMap;
+exports.zip = zip;
+exports.zipBy = zipBy;
+exports.partition = partition;
+exports.unzip = unzip;
 exports.last = last;
 /* No side effect */

tests/analysis_tests/tests/src/expected/Completion.res.txt

@@ -178,6 +178,12 @@ Path Array.
     "tags": [],
     "detail": "(array<'a>, ~start: int=?, ~end: int=?) => array<'a>",
     "documentation": {"kind": "markdown", "value": "\n`slice(array, ~start, ~end)` creates a new array of items copied from `array` from `start` until (but not including) `end`.\n\nSee [`Array.slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice) on MDN.\n\n## Examples\n\n```rescript\n[1, 2, 3, 4]->Array.slice(~start=1, ~end=3) == [2, 3]\n[1, 2, 3, 4]->Array.slice(~start=1) == [2, 3, 4]\n[1, 2, 3, 4]->Array.slice == [1, 2, 3, 4]\n```\n"}
+  }, {
+    "label": "zip",
+    "kind": 12,
+    "tags": [],
+    "detail": "(t<'a>, array<'b>) => array<('a, 'b)>",
+    "documentation": {"kind": "markdown", "value": "\n`zip(a, b)` create an array of pairs from corresponding elements of a and b.\nStop with the shorter array.\n\n## Examples\n\n```rescript\nArray.zip([1, 2], [3, 4, 5]) == [(1, 3), (2, 4)]\n```\n"}
   }, {
     "label": "fillToEnd",
     "kind": 12,
@@ -268,6 +274,12 @@ Path Array.
     "tags": [],
     "detail": "(array<'a>, 'a => 'b) => array<'b>",
     "documentation": {"kind": "markdown", "value": "\n`map(array, fn)` returns a new array with all elements from `array`, each element transformed using the provided `fn`.\n\nSee [`Array.map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map) on MDN.\n\n## Examples\n\n```rescript\nlet array = [\"Hello\", \"Hi\", \"Good bye\"]\nlet mappedArray = array->Array.map(greeting => greeting ++ \" to you\")\n\nmappedArray == [\"Hello to you\", \"Hi to you\", \"Good bye to you\"]\n```\n"}
+  }, {
+    "label": "zipBy",
+    "kind": 12,
+    "tags": [],
+    "detail": "(t<'a>, array<'b>, ('a, 'b) => 'c) => array<'c>",
+    "documentation": {"kind": "markdown", "value": "\n`zipBy(xs, ys, f)` create an array by applying `f` to corresponding elements of\n`xs` and `ys`. Stops with shorter array.\n\nEquivalent to `map(zip(xs, ys), ((a, b)) => f(a, b))`\n\n## Examples\n\n```rescript\nArray.zipBy([1, 2, 3], [4, 5], (a, b) => 2 * a + b) == [6, 9]\n```\n"}
   }, {
     "label": "with",
     "kind": 12,
@@ -538,6 +550,12 @@ Path Array.
     "tags": [1],
     "detail": "(array<'a>, int) => 'a",
     "documentation": {"kind": "markdown", "value": "Deprecated: \n\n\n`unsafe_get(array, index)` returns the element at `index` of `array`.\n\nThis is _unsafe_, meaning it will return `undefined` value if `index` does not exist in `array`.\n\nUse `Array.unsafe_get` only when you are sure the `index` exists (i.e. when using for-loop).\n\n## Examples\n\n```rescript\nlet array = [1, 2, 3]\nfor index in 0 to array->Array.length - 1 {\n  let value = array->Array.unsafe_get(index)\n  Console.log(value)\n}\n```\n"}
+  }, {
+    "label": "partition",
+    "kind": 12,
+    "tags": [],
+    "detail": "(t<'a>, 'a => bool) => (t<'a>, t<'a>)",
+    "documentation": {"kind": "markdown", "value": "\n`partition(f, a)` split array into tuple of two arrays based on predicate `f`;\nfirst of tuple where predicate cause true, second where predicate cause false\n\n## Examples\n\n```rescript\nArray.partition([1, 2, 3, 4, 5], x => mod(x, 2) == 0) == ([2, 4], [1, 3, 5])\n\nArray.partition([1, 2, 3, 4, 5], x => mod(x, 2) != 0) == ([1, 3, 5], [2, 4])\n```\n"}
   }, {
     "label": "copyAllWithin",
     "kind": 12,
@@ -586,6 +604,12 @@ Path Array.
     "tags": [],
     "detail": "(array<'a>, array<'a>) => unit",
     "documentation": {"kind": "markdown", "value": "\n`pushMany(array, itemsArray)` appends many new items to the end of the array.\n\nBeware this will *mutate* the array.\n\nSee [`Array.push`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push) on MDN.\n\n## Examples\n\n```rescript\nlet someArray = [\"hi\", \"hello\"]\n\nsomeArray->Array.pushMany([\"yay\", \"wehoo\"])\nsomeArray == [\"hi\", \"hello\", \"yay\", \"wehoo\"]\n```\n"}
+  }, {
+    "label": "unzip",
+    "kind": 12,
+    "tags": [],
+    "detail": "array<('a, 'b)> => (t<'a>, array<'b>)",
+    "documentation": {"kind": "markdown", "value": "\n`unzip(a)` takes an array of pairs and creates a pair of arrays. The first array\ncontains all the first items of the pairs; the second array contains all the\nsecond items.\n\n## Examples\n\n```rescript\nArray.unzip([(1, 2), (3, 4)]) == ([1, 3], [2, 4])\n\nArray.unzip([(1, 2), (3, 4), (5, 6), (7, 8)]) == ([1, 3, 5, 7], [2, 4, 6, 8])\n```\n"}
   }, {
     "label": "fromIterator",
     "kind": 12,

tests/analysis_tests/tests/src/expected/DotPipeCompletionSpec.res.txt

@@ -270,6 +270,18 @@ Path u
       "range": {"start": {"line": 75, "character": 7}, "end": {"line": 75, "character": 8}},
       "newText": ""
       }]
+  }, {
+    "label": "->Array.unzip",
+    "kind": 12,
+    "tags": [],
+    "detail": "array<('a, 'b)> => (t<'a>, array<'b>)",
+    "documentation": {"kind": "markdown", "value": "\n`unzip(a)` takes an array of pairs and creates a pair of arrays. The first array\ncontains all the first items of the pairs; the second array contains all the\nsecond items.\n\n## Examples\n\n```rescript\nArray.unzip([(1, 2), (3, 4)]) == ([1, 3], [2, 4])\n\nArray.unzip([(1, 2), (3, 4), (5, 6), (7, 8)]) == ([1, 3, 5, 7], [2, 4, 6, 8])\n```\n"},
+    "sortText": "unzip",
+    "insertText": "->Array.unzip",
+    "additionalTextEdits": [{
+      "range": {"start": {"line": 75, "character": 7}, "end": {"line": 75, "character": 8}},
+      "newText": ""
+      }]
   }]
 
 Complete src/DotPipeCompletionSpec.res 80:7