guard.exs

# my blog  : https://trangell.com/fa/
# public : http://iranonrails.ir

defmodule Guard do
  def what_is(x) when is_number(x) do
    IO.puts "#{x} is a number"
  end
  def what_is(x) when is_list(x) do
    IO.puts "#{inspect(x)} is a list"
  end
  def what_is(x) when is_atom(x) do
    IO.puts "#{x} is an atom"
  end
end

Guard.what_is(99)        # => 99 is a number
Guard.what_is(:cat)      # => cat is an atom
Guard.what_is([1,2,3])   # => [1,2,3] is a list

# defmodule Factorial do
#   def of(0), do: 1
#   def of(n) when n > 0 do
#     n * of(n-1)
#   end
# end