about_anonymous_function.exs

#!/usr/bin/env elixir

ExUnit.start

defmodule About_Anonymous_Functions do
    use ExUnit.Case
    use Koans

    think "Declaring an anonymous function referenced by a_variable" do
        a_variable = fn -> "Here the body anonymous function!" end
        # and now execute it!
        assert_? a_variable.() == "Here the body anonymous function!"
    end

    think "Anonymous function and parameter" do
        a_variable = fn(name) -> "Hello #{name}!" end

        assert a_variable.("John") == __?
    end

    think "Anonymous functions in a concise way" do
        a_variable = &("Hello #{&1}!")

       assert a_variable.("John") == __?
    end

    think "Anonymous function with multiple implementation body! Amazing matching power!" do
        a_variable = fn
                       "first body" -> "Running body 1"
                       "second body" -> "Running body 2"
                     end

        assert a_variable.("first body")  == __?
        assert a_variable.("second body") == __?
    end

    think "Another anonymous function with multiple implementation body" do
        a_variable = fn
                       "I want an integer" -> 42
                       "I want a float" -> 1.9
                     end

        assert a_variable.("I want an integer") == __?
        assert a_variable.("I want a float") == __?
    end


    think "It's possible to pass a function in argument of function!" do
      add_five_function = fn(value) -> 5 + value end
      add_ten_after_call_add_five_function = fn(function, value) -> function.(value) + 10 end

      assert add_ten_after_call_add_five_function.(add_five_function, 5) == __?

    end

end