liftOperator

Author: anthonyjoeseph

docs/modules/ObservableEither.ts.md

@@ -31,6 +31,7 @@ Added in v0.6.8
   - [apSecond](#apsecond)
   - [chainFirst](#chainfirst)
   - [flatten](#flatten)
+  - [liftOperator](#liftoperator)
   - [orElse](#orelse)
   - [swap](#swap)
 - [constructors](#constructors)
@@ -255,6 +256,21 @@ export declare const flatten: <E, A>(mma: ObservableEither<E, ObservableEither<E
 
 Added in v0.6.0
 
+## liftOperator
+
+Lifts an OperatorFunction into an ObservableEither context
+Allows e.g. filter to be used on on ObservableEither
+
+**Signature**
+
+```ts
+export declare function liftOperator<E, A, B>(
+  f: OperatorFunction<A, B>
+): (obs: ObservableEither<E, A>) => ObservableEither<E, B>
+```
+
+Added in v0.6.12
+
 ## orElse
 
 **Signature**

docs/modules/ObservableThese.ts.md

@@ -20,6 +20,7 @@ Added in v0.6.12
 - [Functor](#functor)
   - [map](#map)
 - [combinators](#combinators)
+  - [liftOperator](#liftoperator)
   - [swap](#swap)
 - [constructors](#constructors)
   - [both](#both)
@@ -103,6 +104,21 @@ Added in v0.6.12
 
 # combinators
 
+## liftOperator
+
+Lifts an OperatorFunction into an ObservableThese context
+Allows e.g. filter to be used on on ObservableThese
+
+**Signature**
+
+```ts
+export declare function liftOperator<E, A, B>(
+  f: OperatorFunction<A, B>
+): (obs: ObservableThese<E, A>) => ObservableThese<E, B>
+```
+
+Added in v0.6.12
+
 ## swap
 
 **Signature**

docs/modules/ReaderObservableEither.ts.md

@@ -31,6 +31,7 @@ Added in v0.6.10
   - [apSecond](#apsecond)
   - [chainFirst](#chainfirst)
   - [flatten](#flatten)
+  - [liftOperator](#liftoperator)
   - [local](#local)
 - [constructors](#constructors)
   - [ask](#ask)
@@ -246,6 +247,21 @@ export declare const flatten: <R, E, A>(
 
 Added in v0.6.10
 
+## liftOperator
+
+Lifts an OperatorFunction into a ReaderObservableEither context
+Allows e.g. filter to be used on on ReaderObservableEither
+
+**Signature**
+
+```ts
+export declare function liftOperator<R, E, A, B>(
+  f: OperatorFunction<A, B>
+): (obs: ReaderObservableEither<R, E, A>) => ReaderObservableEither<R, E, B>
+```
+
+Added in v0.6.12
+
 ## local
 
 **Signature**

docs/modules/StateReaderObservableEither.ts.md

@@ -29,6 +29,7 @@ Added in v0.6.10
   - [apSecond](#apsecond)
   - [chainFirst](#chainfirst)
   - [flatten](#flatten)
+  - [liftOperator](#liftoperator)
 - [constructors](#constructors)
   - [fromIO](#fromio)
   - [fromObservable](#fromobservable)
@@ -233,6 +234,21 @@ export declare const flatten: <S, R, E, A>(
 
 Added in v0.6.10
 
+## liftOperator
+
+Lifts an OperatorFunction into a StateReaderObservableEither context
+Allows e.g. filter to be used on on StateReaderObservableEither
+
+**Signature**
+
+```ts
+export declare function liftOperator<S, R, E, A, B>(
+  f: OperatorFunction<[A, S], [B, S]>
+): (obs: StateReaderObservableEither<S, R, E, A>) => StateReaderObservableEither<S, R, E, B>
+```
+
+Added in v0.6.12
+
 # constructors
 
 ## fromIO

src/ObservableEither.ts

@@ -17,8 +17,8 @@ import { MonadThrow2 } from 'fp-ts/lib/MonadThrow'
 import { Option } from 'fp-ts/lib/Option'
 import { pipe } from 'fp-ts/lib/pipeable'
 import * as TE from 'fp-ts/lib/TaskEither'
-import { Observable } from 'rxjs'
-import { catchError } from 'rxjs/operators'
+import { defer, merge, Observable, OperatorFunction, Subject } from 'rxjs'
+import { finalize, catchError } from 'rxjs/operators'
 import { MonadObservable2 } from './MonadObservable'
 import * as R from './Observable'
 
@@ -166,6 +166,27 @@ export const swap: <E, A>(ma: ObservableEither<E, A>) => ObservableEither<A, E>
   /*#__PURE__*/
   R.map(E.swap)
 
+/**
+ * Lifts an OperatorFunction into an ObservableEither context
+ * Allows e.g. filter to be used on on ObservableEither
+ *
+ * @category combinators
+ * @since 0.6.12
+ */
+export function liftOperator<E, A, B>(
+  f: OperatorFunction<A, B>
+): (obs: ObservableEither<E, A>) => ObservableEither<E, B> {
+  return obs => {
+    const subj = new Subject<E.Either<E, A>>()
+    return merge(
+      pipe(subj, R.separate, ({ left, right }) => merge(pipe(left, R.map(E.left)), pipe(right, f, R.map(E.right)))),
+      defer(() => {
+        obs.pipe(finalize(() => subj.complete())).subscribe(subj)
+      })
+    )
+  }
+}
+
 // -------------------------------------------------------------------------------------
 // type class members
 // -------------------------------------------------------------------------------------

src/ObservableThese.ts

@@ -15,7 +15,8 @@ import { pipe } from 'fp-ts/lib/pipeable'
 import { Semigroup } from 'fp-ts/lib/Semigroup'
 import * as TT from 'fp-ts/lib/TaskThese'
 import * as TH from 'fp-ts/lib/These'
-import { Observable } from 'rxjs'
+import { defer, merge, Observable, OperatorFunction, Subject } from 'rxjs'
+import { finalize, withLatestFrom } from 'rxjs/operators'
 import * as R from './Observable'
 
 // -------------------------------------------------------------------------------------
@@ -142,6 +143,55 @@ export const swap: <E, A>(ma: ObservableThese<E, A>) => ObservableThese<A, E> =
   /*#__PURE__*/
   R.map(TH.swap)
 
+/**
+ * Lifts an OperatorFunction into an ObservableThese context
+ * Allows e.g. filter to be used on on ObservableThese
+ *
+ * @category combinators
+ * @since 0.6.12
+ */
+export function liftOperator<E, A, B>(
+  f: OperatorFunction<A, B>
+): (obs: ObservableThese<E, A>) => ObservableThese<E, B> {
+  return obs => {
+    const subj = new Subject<TH.These<E, A>>()
+    return merge(
+      pipe(
+        merge(
+          pipe(subj, R.filter(TH.isLeft)),
+          pipe(
+            subj,
+            R.filter(TH.isRight),
+            R.map(({ right }) => right),
+            f,
+            R.map(TH.right)
+          ),
+          pipe(
+            subj,
+            R.filter(TH.isBoth),
+            a =>
+              pipe(
+                a,
+                R.map(({ right }) => right),
+                f,
+                withLatestFrom(
+                  pipe(
+                    a,
+                    R.map(({ left }) => left)
+                  )
+                )
+              ),
+            R.map(([b, e]) => TH.both(e, b))
+          )
+        )
+      ),
+      defer(() => {
+        obs.pipe(finalize(() => subj.complete())).subscribe(subj)
+      })
+    )
+  }
+}
+
 // -------------------------------------------------------------------------------------
 // type class members
 // -------------------------------------------------------------------------------------

src/ReaderObservableEither.ts

@@ -14,6 +14,7 @@ import { MonadThrow3 } from 'fp-ts/lib/MonadThrow'
 import { Option } from 'fp-ts/lib/Option'
 import { pipe } from 'fp-ts/lib/pipeable'
 import * as R from 'fp-ts/lib/Reader'
+import { OperatorFunction } from 'rxjs'
 import { MonadObservable3 } from './MonadObservable'
 import * as OE from './ObservableEither'
 
@@ -103,6 +104,19 @@ export const local: <R2, R1>(
   f: (d: R2) => R1
 ) => <E, A>(ma: ReaderObservableEither<R1, E, A>) => ReaderObservableEither<R2, E, A> = R.local
 
+/**
+ * Lifts an OperatorFunction into a ReaderObservableEither context
+ * Allows e.g. filter to be used on on ReaderObservableEither
+ *
+ * @category combinators
+ * @since 0.6.12
+ */
+export function liftOperator<R, E, A, B>(
+  f: OperatorFunction<A, B>
+): (obs: ReaderObservableEither<R, E, A>) => ReaderObservableEither<R, E, B> {
+  return obs => r => OE.liftOperator<E, A, B>(f)(obs(r))
+}
+
 // -------------------------------------------------------------------------------------
 // type class members
 // -------------------------------------------------------------------------------------

src/StateReaderObservableEither.ts

@@ -13,8 +13,10 @@ import { MonadTask4 } from 'fp-ts/lib/MonadTask'
 import { MonadThrow4 } from 'fp-ts/lib/MonadThrow'
 import { Option } from 'fp-ts/lib/Option'
 import { pipe } from 'fp-ts/lib/pipeable'
+import { OperatorFunction } from 'rxjs'
 import { MonadObservable4 } from './MonadObservable'
 import * as OB from './Observable'
+import * as OE from './ObservableEither'
 import * as ROE from './ReaderObservableEither'
 
 // -------------------------------------------------------------------------------------
@@ -193,6 +195,19 @@ export const apSecond = <S, R, E, B>(
     ap(fb)
   )
 
+/**
+ * Lifts an OperatorFunction into a StateReaderObservableEither context
+ * Allows e.g. filter to be used on on StateReaderObservableEither
+ *
+ * @category combinators
+ * @since 0.6.12
+ */
+export function liftOperator<S, R, E, A, B>(
+  f: OperatorFunction<[A, S], [B, S]>
+): (obs: StateReaderObservableEither<S, R, E, A>) => StateReaderObservableEither<S, R, E, B> {
+  return obs => s => r => OE.liftOperator<E, [A, S], [B, S]>(f)(obs(s)(r))
+}
+
 /**
  * @category Bifunctor
  * @since 0.6.10

test/ObservableEither.ts

@@ -7,7 +7,8 @@ import { pipe } from 'fp-ts/lib/pipeable'
 import { bufferTime } from 'rxjs/operators'
 import * as O from 'fp-ts/lib/Option'
 import * as _ from '../src/ObservableEither'
-import { of as rxOf, Observable, throwError as rxThrowError } from 'rxjs'
+import { of as rxOf, Observable, from, throwError as rxThrowError } from 'rxjs'
+import { filter } from '../src/Observable'
 
 describe('ObservableEither', () => {
   it('rightIO', async () => {
@@ -125,6 +126,20 @@ describe('ObservableEither', () => {
     assert.deepStrictEqual(e, [E.left(1)])
   })
 
+  it('liftOperator (left)', async () => {
+    const e = await pipe(from(['error1', 'error2']), _.leftObservable, _.liftOperator(filter(x => x % 2 === 0)))
+      .pipe(bufferTime(10))
+      .toPromise()
+    assert.deepStrictEqual(e, [E.left('error1'), E.left('error2')])
+  })
+
+  it('liftOperator (right)', async () => {
+    const e = await pipe(from([1, 2, 3, 4]), _.rightObservable, _.liftOperator(filter(x => x % 2 === 0)))
+      .pipe(bufferTime(10))
+      .toPromise()
+    assert.deepStrictEqual(e, [E.right(2), E.right(4)])
+  })
+
   describe('Monad', () => {
     it('of', async () => {
       const fea = _.of(1)

test/ObservableThese.ts

@@ -7,7 +7,8 @@ import { pipe } from 'fp-ts/lib/pipeable'
 import { bufferTime } from 'rxjs/operators'
 import { monoidString } from 'fp-ts/lib/Monoid'
 import * as _ from '../src/ObservableThese'
-import { of as rxOf, Observable } from 'rxjs'
+import { of as rxOf, Observable, from } from 'rxjs'
+import { filter } from '../src/Observable'
 
 describe('ObservableThese', () => {
   it('rightIO', async () => {
@@ -93,6 +94,30 @@ describe('ObservableThese', () => {
     assert.deepStrictEqual(e, [TH.both(2, 1)])
   })
 
+  it('liftOperator (left)', async () => {
+    const e = await pipe(from(['error1', 'error2']), _.leftObservable, _.liftOperator(filter(x => x % 2 === 0)))
+      .pipe(bufferTime(10))
+      .toPromise()
+    assert.deepStrictEqual(e, [TH.left('error1'), TH.left('error2')])
+  })
+
+  it('liftOperator (right)', async () => {
+    const e = await pipe(from([1, 2, 3, 4]), _.rightObservable, _.liftOperator(filter(x => x % 2 === 0)))
+      .pipe(bufferTime(10))
+      .toPromise()
+    assert.deepStrictEqual(e, [TH.right(2), TH.right(4)])
+  })
+
+  it('liftOperator (both)', async () => {
+    const e = await pipe(
+      from([TH.both('error1', 1), TH.both('error2', 2), TH.both('error3', 3), TH.both('error4', 4)]),
+      _.liftOperator(filter(x => x % 2 === 0))
+    )
+      .pipe(bufferTime(10))
+      .toPromise()
+    assert.deepStrictEqual(e, [TH.both('error2', 2), TH.both('error4', 4)])
+  })
+
   it('map', async () => {
     const f = (n: number): number => n * 2
     assert.deepStrictEqual(await pipe(_.right(1), _.map(f)).toPromise(), TH.right(2))