Using Elixir pattern matching to check if a list has an event length of elements

even_length.ex

// Write a function even_length? that uses pattern matching only to return false 
// if the list you pass it has an odd number of elements, true otherwise.

def even_length?([_, _ | t]) do
  even_length?(t)
end

def even_length?([_ | []]) do
  false
end

def even_length?([]) do
  true
end

Even better:

  def even_length?([]) do
    true
  end

  def even_length?([_head | tail]) do
    !even_length?(tail)
  end