Credo

Credo

Credo v1.4.0 Credo.Check.Refactor.NegatedIsNil View Source

This check has a base priority of low and works with any version of Elixir.

Explanation

We should avoid negating the is_nil predicate function. Here are a couple of examples: The code here ...

def fun(%{external_id: external_id, id: id}) when not is_nil(external_id) do
   ...
end

... can be refactored to look like this:

def fun(%{external_id: nil, id: id}) do
  ...
end
def fun(%{external_id: external_id, id: id}) do
  ...
end

... or even better, can match on what you were expecting on the first place:

def fun(%{external_id: external_id, id: id}) when is_binary(external_id) do
  ...
end
def fun(%{external_id: nil, id: id}) do
  ...
end
def fun(%{external_id: external_id, id: id}) do
  ...
end

Similar to negating unless blocks, the reason for this check is not technical, but a human one. If we can use the positive, more direct and human friendly case, we should.

Configuration parameters

There are no parameters for this check.