About ambiguity introduced in function default arguments

Questions & Help Questions
5

You need to do it like this:

defmodule A do
  def f(a, b \\ [])

  def f(a, []), do: "f(#{inspect(a)})"
  def f(a, b) when is_list(b), do: "f(#{inspect(a)}, #{inspect(b)})"
end

IO.puts A.f(5)
# Output --> f(5)

IO.puts A.f(5, [:one, :two])
# Output --> f(5, [:one, :two])