fp-ts-stream's Introduction

Streams for `fp-ts`

This library provides Stream and AsyncStream type classes which uses Generator and AsyncGenerator internally, therefore enabling the developers to have transducers, that are executed as much as they are used. See the following example:

import { range, filter, map, take, toArray } from 'fp-ts-stream/Stream'
import { pipe } from 'fp-ts/lib/function'

// The following will only run/execute the `range` iterator only 4 times.
//
// No array will be allocated, until `toArray` and the rest of the iteration
// will be skipped/not completed.
pipe(
  range(0, 10000),            // iterates 4 times
  filter(it => it % 2 == 1),  // iterates 2 times
  map(it => it * 3),          // ...
  take(2),                    // ...
  toArray,                    // executed once
  console.log
)

The Stream is implementing all the functions that an array would normally have, therefore the instances of it admit implementations such as Traversable, Chain and etc.

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fp-ts-stream's Issues

.sequence stack overflow on large streams

Example:

https://codepen.io/Firfi/pen/ExdwxeK

code for reference:

pipe(Array.from({
  length: 33000
}), STR.fromIterable, STR.map(() => (st: 'state') => [1, st] as [1, 'state']), STR.sequence(ST.Applicative))('state')

I think it happens because it lazily nests functions 2n times https://github.com/incetarik/fp-ts-stream/blob/main/src/Stream/traversable.ts#L90

Tests and docs

Thank you for this library!
Could you please add tests and docs for it?)

Example code in readme doesn't work.

The example code in the readme doesn't work - fp-ts doesn't have a pipe function toArray is probably missing from the import. Also has type errors. I tried ramda's pipe function, but the code didn't work.

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