curry

curry.js

Function.prototype.curry = function curry() {
  var fn = this,
    arity = fn.length,
    slice = Array.prototype.slice,
    args = slice.call( arguments );
 
  function accumulator() {
    var locArgs = args;
 
    if ( arguments.length > 0 ) {
      locArgs = locArgs.concat( slice.call( arguments ) );
    }
 
    if ( locArgs.length >= arity ) {
      return fn.apply( null, locArgs );
    } else {
      return curry.apply( fn, locArgs );
    }
  }
 
  return args.length >= arity ? accumulator() : accumulator;
};

demo.js

function add3nums( a, b, c ) {
  return a + b + c;
}

var curried = add3nums.curry();

curried( 3 )( 4 )( 5 );         // 12
curried( 3, 4 )( 5 );           // 12
curried( 3 )( 4, 5 );           // 12
curried()( 3 )()( 4 )()( 5 );   // 12
curried( 3, 4, 5 );             // 12