ReScript Fluture bindings

Fluture.res

type t<'res, 'err> = Future('res, 'err)

type cancel = unit => unit

// Creation
@module("fluture")
external future: (('res => unit, 'err => unit) => cancel) => t<'res, 'err> = "Future"

let resolve = a =>
  future((res, _rej) => {
    res(a)
    () => ()
  })

let reject = a =>
  future((_res, rej) => {
    rej(a)
    () => ()
  })

let fromPromise = p =>
  future((res, rej) => {
    let _ = p()->Js.Promise.then_(val => {
        res(val)
        Js.Promise.resolve()
      }, _)->Js.Promise.catch(err => {
        rej(err)
        Js.Promise.resolve()
      }, _)
    () => ()
  })

// Consume
@module("fluture")
external _fork: ('res => unit, 'err => unit, t<'res, 'err>) => cancel = "fork"
let fork = (t, res, err) => _fork(res, err, t)

// Transform
@module("fluture")
external _map: ('a => 'b, t<'a, 'err>) => t<'b, 'err> = "map"
let map = (f, mapFn) => _map(mapFn, f)

@module("fluture")
external _chain: ('a => t<'b, 'err>, t<'a, 'err>) => t<'b, 'err> = "chain"
let chain = (f, mapFn) => _chain(mapFn, f)

@module("fluture")
external _mapRej: ('a => 'b, t<'res, 'a>) => t<'res, 'b> = "mapRej"
let mapRej = (f, mapFn) => _mapRej(mapFn, f)

@module("fluture")
external _chainRej: ('a => t<'res, 'b>, t<'res, 'a>) => t<'res, 'b> = "chainRej"
let chainRej = (f, mapFn) => _chainRej(mapFn, f)

let bimap = (f, mapResFn, mapRejFn) => f->map(mapResFn)->mapRej(mapRejFn)

let bichain = (f, mapResFn, mapRejFn) => f->chain(mapResFn)->chainRej(mapRejFn)

let swap = f => f->bichain(reject, resolve)