They are useful for recursion: def factorial(0), do: 1 def factorial(n) when n > 0, do: n * factorial(n - 1) Otherwise it comes down to a matter of ta

They are useful for recursion: def factorial(0), do: 1 def factorial(n) when n > 0, do: n * factorial(n - 1) Otherwise it comes down to a matter of taste. Sometimes they read nicer than a `case`, sometimes a `case` is better. Like I would favour: def zero?(0), do: true def zero?(_), do: false over the case version, for example, but that's just me.