Simple Functional Example in JavaScript Using: `curry` and `compose`

Functional JavaScript - Example 1

//-- Example 1 --------------------------------------------------------
//-- Note - We do not need to reference the data `email` when
//-- using a 'Point free style' of programming

//-- Note - `curry` is from Prelude. `compose` is from Oliver Steele --
//-- http://preludels.com/
//-- http://osteele.com/sources/javascript/functional/

//-- Imparative -------------------------------------------------------
var getUserName = function(email) {
  return email.split('@')[0];
};

//-- Vanilla functionel -----------------------------------------------
//+ split :: Char → String → [String]
var split = function(char) {
  return function(string) {
    return string.split(char);
  };
};

//-- Curry ------------------------------------------------------------
//+ split :: Char → String → [String]
var split = curry(function(char, string) {
  return string.split(char)
});

//+ first :: [a] → a
var first = function(array) {
  return array[0];
};

//-- Point Free -------------------------------------------------------
var getUserName = compose(first, split('@'));
// getUserName('[email protected]') //=> 'takle'

//-- Prelude Lib, Standard Haskell Lib port ---------------------------
var getUserName = compose(Prelude.first, Prelude.split('@'));