Change the order of a function's parameters
Arbitrarily change the order of a function's parameters.
npm install swizzle
var swizzle = require'swizzle';
For the browser, add the following to your pages:
And the global function
swizzle will be available.
...Or using AMD in the browser:
return a - b;//-- Creating a swizzled function is pretty straight//-- forward:var subtractBA = swizzlesubtractAB 1 0;//-- Now, we have a subtract that will flip the order of//-- arguments which is quite useful for partial applicationvar subtract3 = subtractBAbindnull 3;10 99 18mapsubtract3; //=> [7, 96, 15]//-- The thing to remember is that the array serves as a//-- remapping of parameters in a "from" sense.//-- In other words, the array specifies where the parameter//-- in that position in the original function's parameter list//-- obtains its value from the new function's argument list.//-- Some examples to help illustrate the *from* quality:return a b c;// Destination Param: A B Cvar BAC = swizzleABC 1 0 2;BAC1 2 3 //=> [2, 1, 3]var CBA = swizzleABC 2 1 0;CBA1 2 3 //=> [3, 2, 1]var CAC = swizzleABC 2 0 2;CAC1 2 3 //=> [3, 1, 3]
//-- Swizzle can also be added to Function.prototype if that//-- is how you roll:swizzle;varreturn a * b / c;//-- Reorder to place the divisor first and then partially//-- apply divisor:var multDivBy2 = multDivswizzle1 2 0bindnull 2;3 4 5 10reducemultDiv2 //=> 75 ie. product(numbers) / (2 ^ length - 1)//-- Swizzle can even rearrange the arguments of constructor functions//-- for easier partial application of those silly little things:thisw = w;thish = h;return thisw * thish;var Rect30H = swizzleRectangle 1 0bindnull 30;var r20x30 = 20;r20x30area //=> 600
swizzle( yourFunction , paramPositions )
function The function to which you wish to add some secret sauce. For the purposes of currying,
swizzle returns a function with the arity that is implied by the reordering array.
array The positions in the arguments of the new function that the original function's arguments will each be drawn from.
There are no limitations imposed on the
paramPositions array. It tries it's best to do what you ask of it.
For example, if you have a function that takes three arguments.
swizzle(fn, [2, 3, 0]) says "get the first argument(0) from arguments, the second from arguments, and the third from arguments."
That's right! We just turned a 3 parameter function into one that takes 4 parameters but ignores the second argument passed into it. Pretty cool.
v1.1.0 The arity of the returned now grows and shrinks if the parameter reordering implies a function with a different arity
v1.0.0 Initial functionality
Copyright (C) 2013 Jon-Carlos Rivera
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.