1

Author: selfrefactor

CHANGELOG.md

@@ -1,3 +1,9 @@
+11.1.0
+
+- Add `R.filterMap` - similar to Ruby `filter_map`
+
+- Add index to `R.filter`/`R.reject` predicate signiture
+
 11.0.1
 
 - Add missing JS change for `R.includes` and `R.excludes` methods in `11.0.0` release.

files/index.d.ts

@@ -486,7 +486,7 @@ export function filter<T>(
 	predicate: BooleanConstructor,
 ): (list: T[]) => ExcludeFalsy<T>[];
 export function filter<T>(
-	predicate: (value: T) => boolean,
+	predicate: (value: T, index: number) => boolean,
 ): (list: T[]) => T[];
 
 /*
@@ -519,7 +519,7 @@ export function reject<T>(
 	predicate: BooleanConstructor,
 ): (list: T[]) => (null | undefined)[];
 export function reject<T>(
-	predicate: (value: T) => boolean,
+	predicate: (value: T, index: number) => boolean,
 ): (list: T[]) => T[];
 
 /*
@@ -995,12 +995,10 @@ Explanation: It returns the result of looping through `iterable` with `fn`.
 Example:
 
 ```
-const fn = x => x * 2
-
-const iterable = [1, 2]
-const obj = {a: 1, b: 2}
-
-const result = R.map(fn)(iterable),
+const result = R.pipe(
+	[1, 2],
+	R.map(x => x * 2)
+)
 // => [2, 4]
 ```
 
@@ -1017,6 +1015,34 @@ export function map<T extends IterableContainer, U>(
 	fn: (value: T[number]) => U,
 ): (data: T) => Mapped<T, U>;
 
+/*
+Method: filterMap
+
+Explanation: Same as `R.map` but it filters out `null/undefined` if returned from functor functions.
+
+Example:
+
+```
+const result = R.pipe(
+	[1, 2, 3],
+	R.filterMap(x => x > 1 ? x : null)
+)
+// => [2, 3]
+```
+
+Categories: List
+
+Notes: This function doesn't work with objects (use R.mapObject instead)
+
+*/
+// @SINGLE_MARKER
+export function filterMap<T extends IterableContainer, U>(
+	fn: (value: T[number], index: number) => U,
+): (data: T) => Mapped<T, ExcludeFalsy<U>>;
+export function filterMap<T extends IterableContainer, U>(
+	fn: (value: T[number]) => U,
+): (data: T) => Mapped<T, ExcludeFalsy<U>>;
+
 /*
 Method: mapObject
 

source/filter-spec.ts

@@ -4,14 +4,26 @@ const list = [1, 2, 3]
 
 describe('R.filter with array', () => {
   it('within pipe', () => {
-    const _result = pipe(
+    const result = pipe(
       list,
       filter(x => {
         x // $ExpectType number
         return x > 1
       }),
     )
-    _result // $ExpectType number[]
+    result // $ExpectType number[]
+  })
+
+  it('with index', () => {
+    const result = pipe(
+      list,
+      filter((x: number, i: number) => {
+        x // $ExpectType number
+        i // $ExpectType number
+        return x > 1
+      }),
+    )
+    result // $ExpectType number[]
   })
 
   it('complex example', () => {
@@ -50,8 +62,8 @@ describe('R.filter with array', () => {
     const filterBar = (x: T): x is Bar => {
       return typeof (x as Bar).b === 'string'
     }
-    const _result = pipe(testList, filter(filterBar))
-    _result // $ExpectType Bar[]
+    const result = pipe(testList, filter(filterBar))
+    result // $ExpectType Bar[]
   })
 
   it('narrowing type - readonly', () => {
@@ -66,14 +78,14 @@ describe('R.filter with array', () => {
     const filterBar = (x: T): x is Bar => {
       return typeof (x as Bar).b === 'string'
     }
-    const _result = pipe(testList, filter(filterBar))
-    _result // $ExpectType Bar[]
+    const result = pipe(testList, filter(filterBar))
+    result // $ExpectType Bar[]
   })
 
   it('filtering NonNullable - list of objects', () => {
     const testList = [{ a: 1 }, { a: 2 }, false, { a: 3 }]
-    const _result = pipe(testList, filter(Boolean))
-    _result // $ExpectType { a: number; }[]
+    const result = pipe(testList, filter(Boolean))
+    result // $ExpectType { a: number; }[]
   })
 
   it('filtering NonNullable - readonly', () => {

source/filterMap-spec.ts

@@ -0,0 +1,19 @@
+import { filterMap, pipe } from 'rambda'
+
+const list = [1, 2, 3]
+
+it('R.filterMap - within pipe', () => {
+  const result = pipe(
+    list,
+    x => x,
+    filterMap(x => {
+      x // $ExpectType number
+      return Math.random() > 0.5 ? String(x) : null
+    }),
+    filterMap(x => {
+      x // $ExpectType string
+      return Math.random() > 0.5 ? Number(x) : ''
+    }),
+  )
+  result // $ExpectType number[]
+})

source/filterMap.js

@@ -0,0 +1,3 @@
+export function filterMap(fn) {
+  return list => mapFn(fn, list).filter(Boolean)
+}

source/filterMap.spec.js

@@ -0,0 +1,7 @@
+import { filterMap } from './filterMap.js'
+
+const double = x => x > 1 ? x * 2 : null
+
+it('happy', () => {
+  expect(filterMap(double)([1, 2, 3])).toEqual([4, 6])
+})

source/reject-spec.ts

@@ -12,6 +12,17 @@ describe('R.reject with array', () => {
       }),
     )
     result // $ExpectType number[]
+  })
+	it('with index', () => {
+    const result = pipe(
+      list,
+      reject((x: number, i: number) => {
+        x // $ExpectType number
+        i // $ExpectType number
+        return x > 1
+      }),
+    )
+    result // $ExpectType number[]
   })
   it('narrowing type', () => {
     interface Foo {