all-result.ts

// feel free to use as you please, btw.

type T<V, E> = 
    | { t: 'ok', v: V }
    | { t: 'err', e: E }

type UnwrapResultErrors<R> =
    R extends [T<any, infer E>, ...(infer Tail)]
        ? (E | UnwrapResultErrors<Tail>) :
    R extends [T<any, infer E>]
        ? E :
    never;

type UnwrapResultOks<R> =
    R extends [T<infer V, any>, ...(infer Tail)]
        ? [V, ...UnwrapResultOks<Tail>] :
    R extends [T<infer V, any>]
        ? [V] :
    [];

type AllifyResult2Impl<I, O> =
    O extends T<[...infer VO], infer EO> ?
      I extends [T<infer VI, infer EI>, ...(infer Rest)]
        ? AllifyResult2Impl<Rest, T<[...VO, VI], EO | EI>> :
      I extends [T<infer VI, infer EI>]
        ? T<[...VO, VI], EO | EI> :
      never :
    never;

type AllifyResult1<R> = T<UnwrapResultOks<R>, UnwrapResultErrors<R>>;
type AllifyResult2<R> = AllifyResult2Impl<R, T<[], never>>;

export function all1<R extends [...any[]]>(results: [...R]): AllifyResult1<R> {
  const output: any[] = []
  for (const it of results as any) {
    if (!it.ok) return it;
    output.push(it.value);
  }
  return { t: 'ok', v: output } as any;
}

export function all2<R extends [...any[]]>(results: [...R]): AllifyResult2<R> {
  const output: any[] = []
  for (const it of results as any) {
    if (!it.ok) return it;
    output.push(it.value);
  }
  return { t: 'ok', v: output } as any;
}


// this works... (using AllifyResult1)
const a: AllifyResult1<[T<number, undefined>, T<string, undefined>]> = { t: 'ok', v: [1, '' ] };
const b: AllifyResult1<[T<number, undefined>, T<string, undefined>]> = { t: 'err', e: undefined };

// this does not work... (using AllifyResult2)
const c: AllifyResult2<[T<number, undefined>, T<string, undefined>]> = { t: 'ok', v: [1, '' ] };
const d: AllifyResult2<[T<number, undefined>, T<string, undefined>]> = { t: 'err', e: undefined };

// this does not work... (using AllifyResult1)
const e: T<[number, string], undefined> = all1([{ t: 'ok', v: 1 }, { t: 'ok', v: '' }]);
const f: T<[number, string], undefined> = all1([{ t: 'ok', v: 1 }, { t: 'err', e: undefined }]);

// this works... (using AllifyResult2)
const g: T<[number, string], undefined> = all2([{ t: 'ok', v: 1 }, { t: 'ok', v: '' }]);
const h: T<[number, string], undefined> = all2([{ t: 'ok', v: 1 }, { t: 'err', e: undefined }]);

LICENSE

Copyright 2021 Angus Thomsen

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.