In JavaScript, it is possible to partially apply functions (or curry a function).
http://stackoverflow.com/questions/113780/javascript-curry-what-are-the-practical-applications
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Curry functions in JavaScript for 140byt.es
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| function ( | |
| a, // the function to curry or partially apply | |
| b // placeholder variable for splicing arguments | |
| ) { | |
| b = [].slice.call(arguments,1); // convert arguments to an array | |
| return function () { // return a new function which: | |
| return a.apply(this, b.concat(b.slice.call(arguments))) // apply the original function with old arguments combined with new arguments | |
| } | |
| } |
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| function(a,b){b=[].slice.call(arguments,1);return function(){return a.apply(this,b.concat(b.slice.call(arguments)))}} |
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| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| Version 2, December 2004 | |
| Copyright (C) 2011 Eli Perelman <http://eliperelman.com> | |
| Everyone is permitted to copy and distribute verbatim or modified | |
| copies of this license document, and changing it is allowed as long | |
| as the name is changed. | |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION | |
| 0. You just DO WHAT THE FUCK YOU WANT TO. |
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| { | |
| "name": "JavaScriptCurryFunctions140bytes", | |
| "description": "Small function to allow the partial application of JS functions.", | |
| "keywords": [ | |
| "curry", | |
| "partial", | |
| "application", | |
| "javascript", | |
| "curried" | |
| ] | |
| } |
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| <!DOCTYPE html> | |
| <title>JavaScript Partial Function Application (Currying)</title> | |
| <script> | |
| var curry = function(a,b){b=[].slice.call(arguments,1);return function(){return a.apply(this,b.concat(b.slice.call(arguments)))}}; | |
| // this function takes whatever arguments are passed and adds them together | |
| var adder = function() { | |
| var n = 0, args = [].slice.call(arguments); | |
| for (var i = 0, len = args.length; i < len; i++) { | |
| n += args[i]; | |
| } | |
| return n; | |
| }; | |
| // logs: 4 | |
| console.log(adder(2,2)); | |
| // curry adder for later application | |
| var addTwelve = curry(adder, 12); | |
| // logs: 15 | |
| console.log(addTwelve(3)); | |
| // logs: 25 | |
| console.log(addTwelve(3,6,4)); | |
| </script> |
Author
@jed I have tried for a couple hours to no avail. Function.prototype.bind is a toughie. This is what I have so far:
Function.prototype.bind=Date.bind||function(a,b,c,d){b=[].slice.call(arguments,1),c=this,d=function(e){e=b.concat(b.slice.call(arguments));if(!(this instanceof d))return c.apply(a,b);c.apply(this,b)},d.prototype = c.prototype;return d}
as a baseline, i think andrea giammarchi's approach is good:
function(a,b,c){b=[c=this].slice.call(arguments,1);return function(){return a.apply(c,b.concat.apply(b,arguments))}}the hard part is assigning it for bind.
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you should try your hand at shimming
Function.prototype.bind. i tried and couldn't pull it off.