Add liftEither for ObservableEither
#39
Comments
|
Here's a simple example usage import {pipe} from 'fp-ts/pipeable'
import * as r from 'rxjs'
import * as E from 'fp-ts/Either'
import * as OB from 'fp-ts-rxjs/lib/Observable'
import * as OBE from 'fp-ts-rxjs/lib/ObservableEither'
const isOdd = (a: number): boolean => a % 2 !== 0
const fa: OBE.ObservableEither<never, number> = pipe(
r.from([1, 2, 3]),
OBE.rightObservable
)
const fb: OBE.ObservableEither<never, number> = pipe(
fa,
liftEither(OB.filter(isOdd))
)
// fb will emit E.right(1), E.right(3)(edit: a bit more terse) |
|
Just a note - this solution is not ideal, because the input observable is subscribed to twice due to the |
|
Here's a solution without redundant subscriptions: export const liftEither = <Err, A, B>(
f: (a: r.Observable<A>) => r.Observable<B>
) => (obs: OBE.ObservableEither<Err, A>): OBE.ObservableEither<Err, B> => {
const subjA = new r.Subject<A>()
const subjB = new r.Subject<Err>()
obs.subscribe(
E.fold<Err, A, void>(
(err) => subjB.next(err),
(val) => subjA.next(val)
)
)
return r.merge(pipe(subjA, f, OB.map(E.right)), pipe(subjB, OB.map(E.left)))
}(edit: a little more terse) |
Closed
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
I often end up needing a way to use OperatorFunction's on the right case of ObservableEither's
E.g. filter or takeUntil for ObservableEither. Most operators, really
I can make a P.R. if desired, but I'm not sure if this is the best way to do this.
The text was updated successfully, but these errors were encountered: