defmodule Closu do
@moduledoc """
Several examples of closures in elixir
"""

  @doc """
  A small example of currying and closures
  the variable val is in the closure of the returned function
  """
  def curry_plus (val) do
    fn (ival) -> val+ival end
  end

  @doc """
  Because vars are immutable in Elixir, "changing" the
  value of val after defining the function stored in aa
  has no effect
  """
  def curry_plus_ch (val) do
    aa = fn (ival) -> val+ival end
    val = 100
    IO.puts val
    aa
  end

  @doc """
  Closures work on received functions just like on returned functions
  """
  def recv_func(fnn, val) do
    IO.puts fnn.(val)
  end

  def main do
    aa = Closu.curry_plus(7)
    bb = Closu.curry_plus(42)
    IO.puts aa.(6)
    IO.puts bb.(6)

    aaa = Closu.curry_plus_ch(7)
    bbb = Closu.curry_plus_ch(42)
    IO.puts "val ch #{aaa.(6)}"
    IO.puts "val ch #{bbb.(6)}"

    ff = fn (cc) -> aa.(cc)*cc end
    recv_func(ff, 5)
    recv_func(bb, 5)
  end

end

Closu.main