Lists and Recursion

my_list.exs

defmodule MyList do
  def map([], _func), do: []
  def map([ head | tail ], func), do: [ func.(head) | map(tail, func) ]
end

MyList.map [1,2,3,4], fn (n) -> n*n end
MyList.map [1,2,3,4], &(&1 * &1)

reduce.exs

defmodule MyList do
  def reduce([], value, _) do
    value
  end
  def reduce([head | tail], value, func) do
    reduce(tail, func.(head, value), func)
  end
end