@kartheek definitely yours is more performant.

Here’s another version I think even simpler, that builds on your idea.
defguard is_non_empty(term) when term not in [{}, [], %{}]

size is constant time O(1), where as length is linear time -O(N) - Naming conventions — Elixir v1.20.2

Isn’t non_empty for lists a bit more expensive operation - depending on size of list?

Enum.empty?/1 just compares to when it is list.

def empty?(enumerable) when is_list(enumerable) do
    enumerable == []
end

Maybe your non_empty can be changed to this ?

def non_empty(val, _msg) when map_size(val) > 0, do: {:ok, val}
def non_empty(val, _msg) when tuple_size(val) > 0, do: {:ok, val}
def non_empty([], msg), do: {:error, msg}
def non_empty(val, _msg) when is_list(val), do: {:ok, val}
def non_empty(_val, msg), do: {:error, msg}

or something like this only if you pass enumerable or tuple, else this will return {:ok, val} for strings, numbers, etc

  def non_empty([], msg), do: {:error, msg}
  def non_empty({}, msg), do: {:error, msg}
  def non_empty(%{} = val, msg) when map_size(val) == 0, do: {:error, msg}
  def non_empty(val, _msg), do: {:ok, val}

please don’t! It totally changes the logic of the function, unless you are fine with it.
As mentioned by @karthheek, it will return {:ok, } in case of an uncovered type.

non_empty(0, "it is empty") will return {:ok, 0}