distinctBy를 추가하고 distinct를 변경합니다.

src/Garter_Array.res

@@ -89,9 +89,14 @@ let indexBy = (xs, indexFn, ~id) => {
 
 let frequencies = (ar, ~id) => groupBy(ar, Garter_Fn.identity, ~id)->Belt.Map.map(length)
 
-let distinct = (ar, ~id) =>
-  ar
-  ->reduceU((Belt.Set.make(~id), list{}), ((seen, res), v) =>
+let distinctBy = (type a, arr: array<a>, f) => {
+  module Comparable = Belt.Id.MakeComparableU({
+    type t = a
+    let cmp = (a: t, b: t) => Pervasives.compare(f(a), f(b))
+  })
+
+  arr
+  ->reduceU((Belt.Set.make(~id=module(Comparable)), list{}), ((seen, res), v) =>
     if seen->Belt.Set.has(v) {
       (seen, res)
     } else {
@@ -101,6 +106,11 @@ let distinct = (ar, ~id) =>
   ->snd
   ->Belt.List.reverse
   ->Belt.List.toArray
+}
+
+let distinct = arr => {
+  arr->distinctBy(x => x)
+}
 
 let scan = (xs, init, f) => {
   let state = makeUninitializedUnsafe(length(xs))
@@ -235,7 +245,9 @@ module NonEmpty = {
 
   let frequencies = (nxs, ~id) => nxs->frequencies(~id)
 
-  let distinct = (nxs, ~id) => nxs->distinct(~id)->fromArrayExn
+  let distinct = nxs => nxs->distinct->fromArrayExn
+
+  let distinctBy = (nxs, f) => nxs->distinctBy(f)->fromArrayExn
 
   let scan = (nxs, init, f) => nxs->scan(init, f)->fromArrayExn
 

src/Garter_Array.resi

@@ -77,10 +77,15 @@ let indexBy: (array<'a>, 'a => 'b, ~id: Belt.Map.id<'b, 'c>) => Belt.Map.t<'b, '
 */
 let frequencies: (array<'a>, ~id: Belt.Map.id<'a, 'b>) => Belt.Map.t<'a, int, 'b>
 
+/**
+먼저 등장하는 순서를 유지하면서 키에 따라 중복 원소를 제거합니다.
+*/
+let distinctBy: (array<'a>, 'a => 'b) => array<'a>
+
 /**
 먼저 등장하는 순서를 유지하면서 중복 원소를 제거합니다.
 */
-let distinct: (array<'a>, ~id: Belt.Set.id<'a, 'b>) => array<'a>
+let distinct: array<'a> => array<'a>
 
 /**
 `reduce`와 비슷하나 중간 결과를 모두 포함한 `array`를 반환합니다.
@@ -258,7 +263,9 @@ module NonEmpty: {
 
   let frequencies: (t<'a>, ~id: Belt.Map.id<'a, 'b>) => Belt.Map.t<'a, int, 'b>
 
-  let distinct: (t<'a>, ~id: Belt.Set.id<'a, 'b>) => t<'a>
+  let distinct: t<'a> => t<'a>
+
+  let distinctBy: (t<'a>, 'a => 'b) => t<'a>
 
   let scan: (t<'a>, 'b, ('b, 'a) => 'b) => t<'b>
 

test/__tests__/spec/Array_test.res

@@ -32,6 +32,48 @@ zoraBlock("dropWhile", t => {
 
 zoraBlock("keepSome", t => t->testEqual("1", keepSome([Some(1), None, Some(3)]), [1, 3]))
 
+zoraBlock("distinct", t => {
+  t->testEqual("순서를 유지하면서 중복을 제거한다.", distinct([2, 1, 2]), [2, 1])
+})
+
+type a = {
+  id: int,
+  name: string,
+}
+
+zoraBlock("distinctBy", t => {
+  t->testEqual(
+    "순서를 유지하면서 키에 따라 중복을 제거한다.",
+    distinctBy(
+      [
+        {
+          id: 1,
+          name: "foo",
+        },
+        {
+          id: 2,
+          name: "bar",
+        },
+        {
+          id: 3,
+          name: "foo",
+        },
+      ],
+      v => v.name,
+    ),
+    [
+      {
+        id: 1,
+        name: "foo",
+      },
+      {
+        id: 2,
+        name: "bar",
+      },
+    ],
+  )
+})
+
 zoraBlock("intersperse", t => {
   t->testEqual("1", intersperse([], 0), [])
   t->testEqual("2", intersperse([1], 0), [1])