monad TaskRemoteData

TaskRemoteData.ts

import { Monad2 } from 'fp-ts/lib/Monad'
import * as RD from "@devexperts/remote-data-ts"
import * as T from "fp-ts/lib/Task"
import * as TE from "fp-ts/lib/TaskEither"
import * as E from "fp-ts/lib/Either"
import { pipe, pipeable } from "fp-ts/lib/pipeable"
import { sequenceT } from 'fp-ts/lib/Apply'

declare module 'fp-ts/lib/HKT' {
  interface URItoKind2<E, A> {
    TaskRemoteData: TaskRemoteData<E, A>
  }
}

export interface TaskRemoteData<E, A> extends T.Task<RD.RemoteData<E, A>> { }

export const of = <E, A>(a: A): TaskRemoteData<E, A> => T.task.of(RD.remoteData.of<E, A>(a))

export const failure = <E>(e: E): TaskRemoteData<E, never> => T.task.of(RD.failure<E>(e))

export const fromTask = <E, A>(t: T.Task<A>): TaskRemoteData<E, A> =>
  pipe(
    t,
    T.chain(a => of(a))
  )

export const fromTaskEither = <E, A>(te: TE.TaskEither<E, A>): TaskRemoteData<E, A> =>
  pipe(
    te,
    TE.fold(
      (e) => failure(e),
      (v) => of(v)
    )
  )

export const fromEither = <E, A>(e: E.Either<E, A>): TaskRemoteData<E, A> =>
  pipe(
    e,
    E.fold(
      e => failure(e),
      v => of(v)
    )
  )

export const monadTaskRemoteData: Monad2<'TaskRemoteData'> = {
  URI: 'TaskRemoteData',
  of,
  map: (fa, f) => pipe(
    fa,
    T.map(a =>
      pipe(
        a,
        RD.fold(
          () => RD.initial,
          () => RD.pending,
          (e) => RD.failure(e),
          (v) => RD.remoteData.of(f(v))
        )
      )
    )
  ),
  chain: (fa, f) => pipe(
    fa,
    T.chain(a =>
      pipe(
        a,
        RD.fold(
          () => T.task.of(RD.initial),
          () => T.task.of(RD.pending),
          (e) => T.task.of(RD.failure(e)),
          (v) => f(v)
        )
      )
    )
  ),
  ap: (fab, fa) => pipe(
    sequenceT(T.task)(
      fab,
      fa
    ),
    T.map(([fabR, faR]) =>
      pipe(
        sequenceT(RD.remoteData)(
          fabR,
          faR
        ),
        RD.map(([toB, a]) => toB(a)),
      )
    )
  )
}

export const TRD = pipeable(
  monadTaskRemoteData
)