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x/fun/async_either.ts>chainLeft

A collection of algebraic data types, lenses, and schemables based on a light weight higher kinded type implementation. Written for deno.
baetheus/fun
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function chainLeft
import { chainLeft } from "https://deno.land/x/fun@v2.0.0-alpha.6/async_either.ts";

Chain AsyncEither based failures, Left sides, useful for recovering from error conditions.

import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import * as TE from "./async_either.ts";
import * as E from "./either.ts";
import { pipe } from "./fn.ts";

const ta = pipe(
  TE.throwError(1),
  TE.chainLeft(n => TE.of(n*2)),
  TE.chain(n => TE.of(n**2))
)

assertEquals(await ta(), E.right(4))

Parameters

fbtj: (b: B) => AsyncEither<J, I>

Returns

<A>(ta: AsyncEither<B, A>) => AsyncEither<J, A | I>