Elixir 練習問題 ListsAndRecursion-1

defmodule MyList do

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

  def reduce([], value, _func) do
    value
  end
  def reduce([head|tail], value, func) do
    reduce(tail, func.(head, value), func)
  end

  def mapsum(list, func) do
    map(list, func)
    |> reduce(0, &(&1 + &2))
  end

end

^o^ > iex practice_7_1.exs
Eshell V8.0  (abort with ^G)
Interactive Elixir (1.3.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> MyList.mapsum([1, 2, 3], &(&1 * &1))
14