Allow Reader's local to infer the environment type

docs/modules/Reader.ts.md

@@ -315,7 +315,7 @@ Changes the value of the local context during the execution of the action `ma` (
 **Signature**
 
 ```ts
-export declare const local: <R2, R1>(f: (r2: R2) => R1) => <A>(ma: Reader<R1, A>) => Reader<R2, A>
+export declare const local: <R1, R2 = R1>(f: (r2: R2) => R1) => <A>(ma: Reader<R1, A>) => Reader<R2, A>
 ```
 
 Added in v3.0.0

docs/modules/ReaderEither.ts.md

@@ -531,7 +531,9 @@ Changes the value of the local context during the execution of the action `ma` (
 **Signature**
 
 ```ts
-export declare const local: <R2, R1>(f: (r2: R2) => R1) => <E, A>(ma: ReaderEither<R1, E, A>) => ReaderEither<R2, E, A>
+export declare const local: <R1, R2 = R1>(
+  f: (r2: R2) => R1
+) => <E, A>(ma: ReaderEither<R1, E, A>) => ReaderEither<R2, E, A>
 ```
 
 Added in v3.0.0

docs/modules/ReaderIO.ts.md

@@ -387,7 +387,7 @@ Changes the value of the local context during the execution of the action `ma` (
 **Signature**
 
 ```ts
-export declare const local: <R2, R1>(f: (r2: R2) => R1) => <A>(ma: ReaderIO<R1, A>) => ReaderIO<R2, A>
+export declare const local: <R1, R2 = R1>(f: (r2: R2) => R1) => <A>(ma: ReaderIO<R1, A>) => ReaderIO<R2, A>
 ```
 
 Added in v3.0.0

docs/modules/ReaderTask.ts.md

@@ -338,7 +338,7 @@ Changes the value of the local context during the execution of the action `ma` (
 **Signature**
 
 ```ts
-export declare const local: <R2, R1>(f: (r2: R2) => R1) => <A>(ma: ReaderTask<R1, A>) => ReaderTask<R2, A>
+export declare const local: <R1, R2 = R1>(f: (r2: R2) => R1) => <A>(ma: ReaderTask<R1, A>) => ReaderTask<R2, A>
 ```
 
 Added in v3.0.0

docs/modules/ReaderTaskEither.ts.md

@@ -880,7 +880,7 @@ Changes the value of the local context during the execution of the action `ma` (
 **Signature**
 
 ```ts
-export declare const local: <R2, R1>(
+export declare const local: <R1, R2 = R1>(
   f: (r2: R2) => R1
 ) => <E, A>(ma: ReaderTaskEither<R1, E, A>) => ReaderTaskEither<R2, E, A>
 ```

docs/modules/StateReaderTaskEither.ts.md

@@ -770,7 +770,7 @@ Changes the value of the local context during the execution of the action `ma` (
 **Signature**
 
 ```ts
-export declare const local: <R2, R1>(
+export declare const local: <R1, R2 = R1>(
   f: (r2: R2) => R1
 ) => <S, E, A>(ma: StateReaderTaskEither<S, R1, E, A>) => StateReaderTaskEither<S, R2, E, A>
 ```

dtslint/ts4.1/Reader.ts

@@ -1,6 +1,40 @@
 import * as _ from '../../src/Reader'
 import { pipe } from '../../src/function'
 
+declare function modifyA<R extends { a: string }>(r: R): R
+
+//
+// local
+//
+
+// $ExpectType Reader<{ a: string; }, string>
+pipe(
+  _.of<string, { a: string }>('a'),
+  _.local((env) => ({
+    a: env.a
+  }))
+)
+
+// $ExpectType Reader<{ b: string; }, string>
+pipe(
+  _.of<string, { a: string }>('a'),
+  _.local((env: { b: string }) => ({
+    a: env.b
+  }))
+)
+
+// $ExpectType Reader<{ b: string; }, string>
+pipe(
+  _.of<string, { a: string; b: string }>('a'),
+  _.local((env: { b: string }) => ({
+    ...env,
+    a: env.b
+  }))
+)
+
+// $ExpectType Reader<{ a: string; b: string; }, string>
+pipe(_.of<string, { a: string; b: string }>('a'), _.local(modifyA))
+
 //
 // chainW
 //

dtslint/ts4.1/ReaderEither.ts

@@ -3,6 +3,40 @@ import * as R from '../../src/Reader'
 import * as E from '../../src/Either'
 import { pipe } from '../../src/function'
 
+declare function modifyA<R extends { a: string }>(r: R): R
+
+//
+// local
+//
+
+// $ExpectType ReaderEither<{ a: string; }, number, string>
+pipe(
+  _.of<string, { a: string }, number>('a'),
+  _.local((env) => ({
+    a: env.a
+  }))
+)
+
+// $ExpectType ReaderEither<{ b: string; }, number, string>
+pipe(
+  _.of<string, { a: string }, number>('a'),
+  _.local((env: { b: string }) => ({
+    a: env.b
+  }))
+)
+
+// $ExpectType ReaderEither<{ b: string; }, number, string>
+pipe(
+  _.of<string, { a: string; b: string }, number>('a'),
+  _.local((env: { b: string }) => ({
+    ...env,
+    a: env.b
+  }))
+)
+
+// $ExpectType ReaderEither<{ a: string; b: string; }, number, string>
+pipe(_.of<string, { a: string; b: string }, number>('a'), _.local(modifyA))
+
 //
 // getOrElseW
 //

dtslint/ts4.1/ReaderIO.ts

@@ -0,0 +1,36 @@
+import * as _ from '../../src/ReaderIO'
+import { pipe } from '../../src/function'
+
+declare function modifyA<R extends { a: string }>(r: R): R
+
+//
+// local
+//
+
+// $ExpectType ReaderIO<{ a: string; }, string>
+pipe(
+  _.of<string, { a: string }>('a'),
+  _.local((env) => ({
+    a: env.a
+  }))
+)
+
+// $ExpectType ReaderIO<{ b: string; }, string>
+pipe(
+  _.of<string, { a: string }>('a'),
+  _.local((env: { b: string }) => ({
+    a: env.b
+  }))
+)
+
+// $ExpectType ReaderIO<{ b: string; }, string>
+pipe(
+  _.of<string, { a: string; b: string }>('a'),
+  _.local((env: { b: string }) => ({
+    ...env,
+    a: env.b
+  }))
+)
+
+// $ExpectType ReaderIO<{ a: string; b: string; }, string>
+pipe(_.of<string, { a: string; b: string }>('a'), _.local(modifyA))

dtslint/ts4.1/ReaderTask.ts

@@ -1,6 +1,40 @@
 import * as _ from '../../src/ReaderTask'
 import { pipe } from '../../src/function'
 
+declare function modifyA<R extends { a: string }>(r: R): R
+
+//
+// local
+//
+
+// $ExpectType ReaderTask<{ a: string; }, string>
+pipe(
+  _.of<string, { a: string }>('a'),
+  _.local((env) => ({
+    a: env.a
+  }))
+)
+
+// $ExpectType ReaderTask<{ b: string; }, string>
+pipe(
+  _.of<string, { a: string }>('a'),
+  _.local((env: { b: string }) => ({
+    a: env.b
+  }))
+)
+
+// $ExpectType ReaderTask<{ b: string; }, string>
+pipe(
+  _.of<string, { a: string; b: string }>('a'),
+  _.local((env: { b: string }) => ({
+    ...env,
+    a: env.b
+  }))
+)
+
+// $ExpectType ReaderTask<{ a: string; b: string; }, string>
+pipe(_.of<string, { a: string; b: string }>('a'), _.local(modifyA))
+
 //
 // Do
 //

dtslint/ts4.1/ReaderTaskEither.ts

@@ -5,6 +5,40 @@ import * as TE from '../../src/TaskEither'
 import * as IOE from '../../src/IOEither'
 import { pipe } from '../../src/function'
 
+declare function modifyA<R extends { a: string }>(r: R): R
+
+//
+// local
+//
+
+// $ExpectType ReaderTaskEither<{ a: string; }, number, string>
+pipe(
+  _.of<string, { a: string }, number>('a'),
+  _.local((env) => ({
+    a: env.a
+  }))
+)
+
+// $ExpectType ReaderTaskEither<{ b: string; }, number, string>
+pipe(
+  _.of<string, { a: string }, number>('a'),
+  _.local((env: { b: string }) => ({
+    a: env.b
+  }))
+)
+
+// $ExpectType ReaderTaskEither<{ b: string; }, number, string>
+pipe(
+  _.of<string, { a: string; b: string }, number>('a'),
+  _.local((env: { b: string }) => ({
+    ...env,
+    a: env.b
+  }))
+)
+
+// $ExpectType ReaderTaskEither<{ a: string; b: string; }, number, string>
+pipe(_.of<string, { a: string; b: string }, number>('a'), _.local(modifyA))
+
 //
 // getOrElseW
 //

dtslint/ts4.1/StateReaderTaskEither.ts

@@ -5,6 +5,40 @@ import * as RTE from '../../src/ReaderTaskEither'
 import * as IOE from '../../src/IOEither'
 import { pipe } from '../../src/function'
 
+declare function modifyA<R extends { a: string }>(r: R): R
+
+//
+// local
+//
+
+// $ExpectType StateReaderTaskEither<boolean, { a: string; }, number, string>
+pipe(
+  _.of<string, boolean, { a: string }, number>('a'),
+  _.local((env) => ({
+    a: env.a
+  }))
+)
+
+// $ExpectType StateReaderTaskEither<boolean, { b: string; }, number, string>
+pipe(
+  _.of<string, boolean, { a: string }, number>('a'),
+  _.local((env: { b: string }) => ({
+    a: env.b
+  }))
+)
+
+// $ExpectType StateReaderTaskEither<boolean, { b: string; }, number, string>
+pipe(
+  _.of<string, boolean, { a: string; b: string }, number>('a'),
+  _.local((env: { b: string }) => ({
+    ...env,
+    a: env.b
+  }))
+)
+
+// $ExpectType StateReaderTaskEither<boolean, { a: string; b: string; }, number, string>
+pipe(_.of<string, boolean, { a: string; b: string }, number>('a'), _.local(modifyA))
+
 //
 // chainW
 //

src/Reader.ts

@@ -76,7 +76,7 @@ export const asksReader: <R, A>(f: (r: R) => Reader<R, A>) => Reader<R, A> = ask
  * @category combinators
  * @since 3.0.0
  */
-export const local = <R2, R1>(f: (r2: R2) => R1) => <A>(ma: Reader<R1, A>): Reader<R2, A> => (r2) => ma(f(r2))
+export const local = <R1, R2 = R1>(f: (r2: R2) => R1) => <A>(ma: Reader<R1, A>): Reader<R2, A> => (r2) => ma(f(r2))
 
 /**
  * `map` can be used to turn functions `(a: A) => B` into functions `(fa: F<A>) => F<B>` whose argument and return types

src/ReaderEither.ts

@@ -230,7 +230,7 @@ export const toUnion: <R, E, A>(fa: ReaderEither<R, E, A>) => Reader<R, E | A> =
  * @category combinators
  * @since 3.0.0
  */
-export const local: <R2, R1>(f: (r2: R2) => R1) => <E, A>(ma: ReaderEither<R1, E, A>) => ReaderEither<R2, E, A> =
+export const local: <R1, R2 = R1>(f: (r2: R2) => R1) => <E, A>(ma: ReaderEither<R1, E, A>) => ReaderEither<R2, E, A> =
   R.local
 
 /**

src/ReaderIO.ts

@@ -59,7 +59,7 @@ export const fromIO: FromIO2<URI>['fromIO'] = /*#__PURE__*/ R.of
  * @category combinators
  * @since 3.0.0
  */
-export const local: <R2, R1>(f: (r2: R2) => R1) => <A>(ma: ReaderIO<R1, A>) => ReaderIO<R2, A> = R.local
+export const local: <R1, R2 = R1>(f: (r2: R2) => R1) => <A>(ma: ReaderIO<R1, A>) => ReaderIO<R2, A> = R.local
 
 /**
  * Less strict version of [`asksReaderIO`](#asksreaderio).

src/ReaderTask.ts

@@ -100,7 +100,7 @@ export const fromIO: FromIO2<URI>['fromIO'] =
  * @category combinators
  * @since 3.0.0
  */
-export const local: <R2, R1>(f: (r2: R2) => R1) => <A>(ma: ReaderTask<R1, A>) => ReaderTask<R2, A> = R.local
+export const local: <R1, R2 = R1>(f: (r2: R2) => R1) => <A>(ma: ReaderTask<R1, A>) => ReaderTask<R2, A> = R.local
 
 /**
  * `map` can be used to turn functions `(a: A) => B` into functions `(fa: F<A>) => F<B>` whose argument and return types

src/ReaderTaskEither.ts

@@ -369,7 +369,7 @@ export const chainNullableK: <E>(
  * @category combinators
  * @since 3.0.0
  */
-export const local: <R2, R1>(
+export const local: <R1, R2 = R1>(
   f: (r2: R2) => R1
 ) => <E, A>(ma: ReaderTaskEither<R1, E, A>) => ReaderTaskEither<R2, E, A> = R.local
 

src/StateReaderTaskEither.ts

@@ -248,7 +248,7 @@ export const fromReaderTaskEither: NaturalTransformation34<RTE.URI, URI> =
  * @category combinators
  * @since 3.0.0
  */
-export const local = <R2, R1>(f: (r2: R2) => R1) => <S, E, A>(
+export const local = <R1, R2 = R1>(f: (r2: R2) => R1) => <S, E, A>(
   ma: StateReaderTaskEither<S, R1, E, A>
 ): StateReaderTaskEither<S, R2, E, A> => flow(ma, R.local(f))