A Javascript function for automatically creating a currying version of a function. It takes the number of arguments of the function (must be fixed) and the function.

autocurry.js

function autoCurry(n, f) {
  return function() {
    var args1 = Array.prototype.slice.apply(arguments),
        len   = args1.length;
    if(len === n) {
      return f.apply(this, args1);
    } else if(len > n) {
      throw 'Too many arguments.';
    } else {
      return autoCurry(n - len, function() {
        var args2 = Array.prototype.slice.apply(arguments);
        return f.apply(this, args1.concat(args2));
      });
    }
  }
}

// example

function map(f, a) {
  var len = a.length,
      ret = new Array(len),
      i;
  for(i = 0; i < len; i++) {
    ret[i] = f(a[i]);
  }
  return ret;
}

var mapC = autoCurry(2, map);

var incrementor = mapC(function(i){ return i + 1; });

incrementor([1,2,3]); //=> [2,3,4]

function zipWith(f, a, b) {
  var l1 = a.length,
      l2 = b.length,
      l  = l1 < l2 ? l1 : l2,
      ret = new Array(l),
      i;
  for(i = 0; i < l; i++) {
    ret[i] = f(a[i], b[i]); 
  }
  return ret;
}

var zipWithC = autoCurry(3, zipWith);

var zipAdd = zipWithC(function(i, j) {return i + j;});

var zipAddFirst3 = zipAdd([1,2,3]);

zipAddFirst3([10, 100, 1000]); //=> [11, 102, 1003]