I thought this also. It was a bit confusing but I just black-boxed it as “this is how you do it”.
I will say, however, that my understanding of Erlang/Elixir patterns was much improved just from looking at this lib. I had thought of patterns as the entire function signature, and I didn’t realize that Erlang docs give each argument match as individual patterns…So I gotta say thanks just for that. Huge improvement on my misconception.
PS I have started to convert my command functions (command pattern) to use this lib. It’s great. 
