decurry

decurry v2.0.1

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 ([e-mail])

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