Partial Functions / Currying

currying.ex

# Another example for: http://onor.io/2014/03/31/partial-function-application-in-elixir/

defmodule PartFuncs do
  defp addfun(x, y), do: x + y

  # return a partially applied function
  def add(a), do: &addfun(a, &1)
  
  # could also easily be written as: addfun(a, b)
  def add(a, b), do: (&addfun/2).(a, b)
end

# USAGE

partfun = PartFuncs.add(22)
#=> #Function<0.115088320/1 in PartFuncs.add/1>

partfun.(20)
#=> 42

PartFuncs.add(22).(20)
#=> 42

currying.js

PartFuncs = {
  add: function (a, b) {
    // implementation of the logic
    var addfun = function (x, y) { return (x + y) }

    if (typeof b === "undefined") {
      // a function which holds the partially applied value
      return (function (value) {
        return addfun(this, value)
      }).bind(a)
    } else {
      return addfun(a, b)
    }
  }
}

// USAGE

var partfun = PartFuncs.add(22)
//=> function () { [native code] }

partfun(20)
//=> 42

PartFuncs.add(22)(20)
//=> 42