decurry

decurry is the 'reverse' of curry: given a composed function `fn(arg1)(arg2)(arg3)` it returns a function that can be called as `fn(arg1, arg2, arg3)` or `fn(arg1, arg2)(arg3) etc.`

Usage no npm install needed!

<script type="module">
  import decurry from 'https://cdn.skypack.dev/decurry';
</script>

README

decurry v2.0.1

Build Status

The decurry higher order function, is like the the reverse of curry.

Motivation

It works the same as Ramda's R.uncurryN BUT unlike it, it works ALWAYS - for both manual and R.compose curried functions. See the 2nd test in decurry-spec where R.uncurryN fails (as of December 2017, v0.25.0). Why, I dont know, TBO I haven't checked their code, but the documentation says "Returns a function of arity n from a (manually) curried function."!

Why do we need decurry?

When we compose a 'curried' function, due to composition (eg with R.compose or lodash's flowRight ), the curried function has to be called strictly as fn(arg1)(arg2)(arg3) etc, to yield its final result. Each argument has to be passed one by one, which seems tedious and unnatural.

With decurry we get back a decurried function that can be called as one-by-one, but also in any combination of arguments arrangements, for example:

fn(arg1)(arg2)(arg3)

fn(arg1, arg2, arg3)

fn(arg1)(arg2, arg3)

fn(arg1, arg2)(arg3)

fn(arg1)(arg2)(arg3)

etc, are all equivalent.

Usage:

var _f = require('lodash/fp');

var tasks = [
  {
    username: 'Michael', title: 'Curry stray functions',
    complete: true, effort: 'low', priority: 'high'
  },
  {
    username: 'Scott', title: 'Add `fork` function',
    complete: true, effort: 'low', priority: 'low'
  },
];

project = _f.flowRight([_f.map, _f.pick]);

project(['title', 'priority'])(tasks);
// works fine, as its called with (arg1)(arg2) and it returns
// [ { title: 'Curry stray functions', priority: 'high' },
//   { title: 'Add `fork` function', priority: 'low' }    ]

project(['title', 'priority'], tasks);
// doesn't work, `tasks` is completely ignored and it returns a function that is waiting for `tasks` to yield results

decurriedProject = decurry(2, project);

decurriedProject(['title', 'priority'], tasks); // works fine
decurriedProject(['title', 'priority'])(tasks); // works fine also

The same goes for functions with larger arity.

Copyright(c) 2016-2017 Angelos Pikoulas (agelos.pikoulas@gmail.com)

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.