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 )
functionThe function to which you wish to add some secret sauce. For the purposes of currying,
swizzlereturns a function with the arity that is implied by the reordering array.
arrayThe 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
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