Reader: add apFirstW and apSecondW

gcanti · Aug 22, 2021 · 21e03f1 · 21e03f1
1 parent 32820bd
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diff --git a/docs/modules/Reader.ts.md b/docs/modules/Reader.ts.md
@@ -36,7 +36,9 @@ Added in v2.0.0
   - [second](#second)
 - [combinators](#combinators)
   - [apFirst](#apfirst)
+  - [apFirstW](#apfirstw)
   - [apSecond](#apsecond)
+  - [apSecondW](#apsecondw)
   - [asksReader](#asksreader)
   - [asksReaderW](#asksreaderw)
   - [chainFirst](#chainfirst)
@@ -257,6 +259,18 @@ export declare const apFirst: <E, B>(second: Reader<E, B>) => <A>(first: Reader<
 
 Added in v2.0.0
 
+## apFirstW
+
+Less strict version of [`apFirst`](#apfirst).
+
+**Signature**
+
+```ts
+export declare const apFirstW: <R2, A, B>(second: Reader<R2, B>) => <R1>(first: Reader<R1, A>) => Reader<R1 & R2, A>
+```
+
+Added in v2.12.0
+
 ## apSecond
 
 Combine two effectful actions, keeping only the result of the second.
@@ -271,6 +285,18 @@ export declare const apSecond: <E, B>(second: Reader<E, B>) => <A>(first: Reader
 
 Added in v2.0.0
 
+## apSecondW
+
+Less strict version of [`apSecond`](#apsecond).
+
+**Signature**
+
+```ts
+export declare const apSecondW: <R2, A, B>(second: Reader<R2, B>) => <R1>(first: Reader<R1, A>) => Reader<R1 & R2, B>
+```
+
+Added in v2.12.0
+
 ## asksReader
 
 Effectfully accesses the environment.

diff --git a/src/Reader.ts b/src/Reader.ts
@@ -283,6 +283,16 @@ export const apFirst =
   /*#__PURE__*/
   apFirst_(Apply)
 
+/**
+ * Less strict version of [`apFirst`](#apfirst).
+ *
+ * @category combinators
+ * @since 2.12.0
+ */
+export const apFirstW: <R2, A, B>(second: Reader<R2, B>) => <R1>(first: Reader<R1, A>) => Reader<R1 & R2, A> =
+  /*#__PURE__*/
+  apFirst as any
+
 /**
  * Combine two effectful actions, keeping only the result of the second.
  *
@@ -295,6 +305,16 @@ export const apSecond =
   /*#__PURE__*/
   apSecond_(Apply)
 
+/**
+ * Less strict version of [`apSecond`](#apsecond).
+ *
+ * @category combinators
+ * @since 2.12.0
+ */
+export const apSecondW: <R2, A, B>(second: Reader<R2, B>) => <R1>(first: Reader<R1, A>) => Reader<R1 & R2, B> =
+  /*#__PURE__*/
+  apSecond as any
+
 /**
  * @category instances
  * @since 2.7.0

diff --git a/test/Reader.ts b/test/Reader.ts
@@ -24,10 +24,20 @@ describe('Reader', () => {
       U.deepStrictEqual(pipe(_.of('a'), _.apFirst(_.of('b')))({}), 'a')
     })
 
+    it('apFirstW', () => {
+      const fb = _.of<{ readonly k: string }, boolean>(true)
+      U.deepStrictEqual(pipe(_.of<{ readonly x: number }, string>('foo'), _.apFirstW(fb))({ x: 1, k: 'v' }), 'foo')
+    })
+
     it('apSecond', () => {
       U.deepStrictEqual(pipe(_.of('a'), _.apSecond(_.of('b')))({}), 'b')
     })
 
+    it('apSecondW', () => {
+      const fb = _.of<{ readonly k: string }, boolean>(true)
+      U.deepStrictEqual(pipe(_.of<{ readonly x: number }, string>('foo'), _.apSecondW(fb))({ x: 1, k: 'v' }), true)
+    })
+
     it('chain', () => {
       const f = (s: string): _.Reader<object, number> => _.of(s.length)
       U.deepStrictEqual(pipe(_.of('foo'), _.chain(f))({}), 3)