https://github.com/janstuemmel/yep

Easy functional programming with Typescript
https://github.com/janstuemmel/yep

category-theory fp functional-programming futures javascript promises typescript

Last synced: 15 days ago
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Easy functional programming with Typescript

• Host: GitHub
• URL: https://github.com/janstuemmel/yep
• Owner: janstuemmel
• License: mit
• Created: 2024-03-15T18:21:20.000Z (10 months ago)
• Default Branch: main
• Last Pushed: 2024-07-01T12:06:47.000Z (6 months ago)
• Last Synced: 2024-11-07T01:13:46.042Z (2 months ago)
• Topics: category-theory, fp, functional-programming, futures, javascript, promises, typescript
• Language: TypeScript
• Homepage:
• Size: 91.8 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# yep

A functional programming library that treats every result as promise 

and therefor doesn't differentiate between async and sync code.

The code should showcase that fp is not hard in typecript.

Please look at examples and tests.

## Usage

```ts

import {type Box, all, flat, map, nah, or, pipe, tap, yep} from './lib.js';

class HttpError extends Error {}

class ParseError extends Error {}

const req = (url: string): Box =>

  fetch(url)

    .then(yep)

    .catch(() => nah(new HttpError('http error')));

const parse = (res: Response): Box =>

  res

    .json()

    .then((json) => yep(json as T))

    .catch(() => nah(new ParseError('json parse error')));

const checkStatus = (res: Response) =>

  res.status >= 400 ? nah(new HttpError('status error')) : yep(res);

const getPokemon = (name: string) =>

  pipe(

    yep(`https://pokeapi.co/api/v2/pokemon/${name}`),

    flat(req),

    tap((res) => console.log(`Requested ${name} with response status ${res.status}`)),

    flat(checkStatus),

    flat(parse<{weight: number; name: string}>),

  );

const program = pipe(

  yep(['ditto', 'onix']),

  flat((names) => all(names.map(getPokemon))),

  map(([v, w]) =>

    v.weight < w.weight

      ? `${w.name} heavier then ${v.name}`

      : `${v.name} heavier then ${w.name}`,

  ),

  or((e) => yep(`recovered err: ${e.message}`)),

);

program.then(console.log);

```