cases.ex

defmodule T1 do

  def t(arg) do
    a = [
      %{
        fn: &f1/1, 
        res: :res1
      }, %{
        fn: &f2/1, 
        res: :res2
      },  %{
        res: :res3, 
        fn: &f3(&1, 2)
      }
    ]
    w_apply(a, arg)
  end

  defp w_apply([head|tail], arg) do
    case (head.fn).(arg) do
      true -> {:ok, head.res}
      _ -> w_apply(tail, arg)
    end
  end

  defp w_apply([], arg) do
    {:err, arg}
  end

  defp f1(x) do
    x == 1
  end  
  
  defp f2(x) do
    x == 2
  end  
  
  defp f3(x, _y) do
    x == 3
  end  
end