curry-d

curry-d

An implementation of curry that uses a dispatcher to achieve arbitrary curry length. This micro library trades the ability to check arity with length (it's len instead) for ~2.2x perf on high arity functions and 1.2x on <= 10 and increased flexibility (decide if there should be only one arg and allow extra args).

Usage

Node

Install as usual:

npm install curry-d

Functions are props of exports

var bint = require('curry-d').curryRight(parseInt)(2);
bint('101010'); // 42

RequireJS

Add the path to curry-d, then require as usual:

define(function () {
    var bint = require('curry-d').curryRight(parseInt)(2);
    bint('101010'); // 42
});

Globally in the browser

var bint = curryRight(parseInt)(2);
bint('101010'); // 42

Functions

This module exports three functions: curry, curryRight, and uncurry.

curry

curry fills a functions signature from left to right until all args are defined:

var add = function (a, b) {
    return a + b;
};

// add.length === 2, so it must be given two args.
var curried = curry(add)(40); // a function
curried(2); // 42

In case you need to curry a varargs function you can specify the number of arguments desired at curry time:

var sum = function () {
    return require('lodash').reduce(arguments, function (total, n) {return total + n;});
};

var curried = curry(sum)(40); // undefined
var curried = curry(sum, 2)(40); // a function
curried(2); // 42

You can optionally add multiple arguments in each call:

curry(sum, 2)(40, 2); // 42

Unless you want to force a single argument per call (handy w/ e.g., _.forEach):

curry(sum, 2, true)(40, 99)(2); // 42

However, you cannot overflow your arguments:

curry(sum, 2)(40, 2, 99); // 42

Unless you really want to:

curry(sum, null, null, false)(40, 2, 99); // 141

curryRight

curryRight works just like curry, but in the opposite direction:

var divide = function (a, b) {
    return a / b;
};

curry(divide)(1, 2); // .5

curryRight(divide)(1, 2); // 2

uncurry

uncurry takes a curried function and returns the original. Handy if you've curried something but need the original too. Or if you're unsure if something is curried, uncurry is a noop if the function is not curried:

uncurry(curry(divide)(1)) === divide; // true