You can also use the pipe after the case statement.
Here’s an example which includes concatenating the string before sending it to url_decode64 function:
defp urldec64(data) do data <> case rem(byte_size(data), 4) do 2 -> "==" 3 -> "=" _ -> "" end |> url_decode64! end
Now I think that’s really expressive and easy to read. Having said that, I don’t know how many people will agree with me 
