Quite the opposite :) My preference would be to rely on pattern matching (unification) in the function head: def transform_data([_|[]]) do: [] I just want

Quite the opposite :) My preference would be to rely on pattern matching (unification) in the function head: def transform_data([_|[]]) do: [] I just wanted an example of using guard clauses. It does depend on the actual code though, there's probably a more elixiry solution.