refactor(array): bind to native reduce instead of reimplementing it

Author: glennsl

src/Core__Array.mjs

@@ -46,15 +46,6 @@ function sort(arr, cmp) {
   return result;
 }
 
-function reduce(a, x, f) {
-  var f$1 = Curry.__2(f);
-  var r = x;
-  for(var i = 0 ,i_finish = a.length; i < i_finish; ++i){
-    r = f$1(r, a[i]);
-  }
-  return r;
-}
-
 function reduceWithIndex(a, x, f) {
   var f$1 = Curry.__3(f);
   var r = x;
@@ -155,7 +146,6 @@ export {
   sort ,
   indexOfOpt ,
   lastIndexOfOpt ,
-  reduce ,
   reduceReverse ,
   reduceWithIndex ,
   findIndexOpt ,

src/Core__Array.res

@@ -127,15 +127,7 @@ let sort = (arr, cmp) => {
 @send external map: (array<'a>, 'a => 'b) => array<'b> = "map"
 @send external mapWithIndex: (array<'a>, ('a, int) => 'b) => array<'b> = "map"
 
-let reduceU = (a, x, f) => {
-  let r = ref(x)
-  for i in 0 to length(a) - 1 {
-    r.contents = f(. r.contents, getUnsafe(a, i))
-  }
-  r.contents
-}
-
-let reduce = (a, x, f) => reduceU(a, x, (. a, b) => f(a, b))
+@send external reduce: (array<'b>, ('a, 'b) => 'a, 'a) => 'a = "reduce"
 
 let reduceWithIndexU = (a, x, f) => {
   let r = ref(x)

src/Core__Array.resi

@@ -59,17 +59,18 @@ let lastIndexOfOpt: (array<'a>, 'a) => option<int>
 @send external mapWithIndex: (array<'a>, ('a, int) => 'b) => array<'b> = "map"
 
 /**
-  `reduce(xs, init, f)`
+  `reduce(xs, f, init)`
 
   Applies `f` to each element of `xs` from beginning to end. Function `f` has two parameters: the item from the list and an “accumulator”; which starts with a value of `init`. `reduce` returns the final value of the accumulator.
 
   ```res example
-  Array.reduce([2, 3, 4], 1, (a, b) => a + b) == 10
+  Array.reduce([2, 3, 4], (a, b) => a + b, 1) == 10
 
-  Array.reduce(["a", "b", "c", "d"], "", (a, b) => a ++ b) == "abcd"
+  Array.reduce(["a", "b", "c", "d"], (a, b) => a ++ b, "") == "abcd"
   ```
 */
-let reduce: (array<'b>, 'a, ('a, 'b) => 'a) => 'a
+@send
+external reduce: (array<'b>, ('a, 'b) => 'a, 'a) => 'a = "reduce"
 
 /**
   `reduceReverse(xs, init, f)`

test/ArrayTests.mjs

@@ -52,11 +52,11 @@ Test.run([
         28
       ],
       "reduce"
-    ], Core__Array.reduce([
-          1,
-          2,
-          3
-        ], /* [] */0, Core__List.add), eq, {
+    ], [
+        1,
+        2,
+        3
+      ].reduce(Core__List.add, /* [] */0), eq, {
       hd: 3,
       tl: {
         hd: 2,
@@ -75,7 +75,7 @@ Test.run([
         36
       ],
       "reduce - empty"
-    ], Core__Array.reduce([], /* [] */0, Core__List.add), eq, /* [] */0);
+    ], [].reduce(Core__List.add, /* [] */0), eq, /* [] */0);
 
 Test.run([
       [

test/ArrayTests.res

@@ -11,8 +11,8 @@ Test.run(
   [3, 4, 5, 6, 7, 8, 9],
 )
 
-Test.run(__POS_OF__("reduce"), Array.reduce([1, 2, 3], list{}, List.add), eq, list{3, 2, 1})
-Test.run(__POS_OF__("reduce - empty"), Array.reduce([], list{}, List.add), eq, list{})
+Test.run(__POS_OF__("reduce"), Array.reduce([1, 2, 3], List.add, list{}), eq, list{3, 2, 1})
+Test.run(__POS_OF__("reduce - empty"), Array.reduce([], List.add, list{}), eq, list{})
 
 Test.run(
   __POS_OF__("reduceReverse"),

test/TempTests.mjs

@@ -4,7 +4,6 @@ import * as Core__Int from "../src/Core__Int.mjs";
 import * as Core__Dict from "../src/Core__Dict.mjs";
 import * as Core__JSON from "../src/Core__JSON.mjs";
 import * as Caml_option from "rescript/lib/es6/caml_option.js";
-import * as Core__Array from "../src/Core__Array.mjs";
 import * as Core__Float from "../src/Core__Float.mjs";
 import * as Core__BigInt from "../src/Core__BigInt.mjs";
 import * as Core__Option from "../src/Core__Option.mjs";
@@ -22,11 +21,11 @@ var array = [
   4
 ];
 
-console.info(Core__Array.reduce(array.map(function (x) {
-              return (x << 1);
-            }), 0, (function (a, b) {
+console.info(array.map(function (x) {
+            return (x << 1);
+          }).reduce((function (a, b) {
             return a + b | 0;
-          })));
+          }), 0));
 
 console.info(typeof array);
 

test/TempTests.res

@@ -4,7 +4,7 @@ Console.info("")
 Console.info("Array")
 Console.info("---")
 let array = [1, 2, 3, 4]
-Console.info(array->Array.map(x => x * 2)->Array.reduce(0, (a, b) => a + b))
+Console.info(array->Array.map(x => x * 2)->Array.reduce((a, b) => a + b, 0))
 Console.info(typeof(array))
 
 Console.info("")