Thanks for the feedback. The ~ is a substitute for :, which is used in other languages for optional type annotations. You're right about removing ~ altogether, Go style. ~Function(Int -> Int -> Int) is a function which takes two integers, and returns one. I've mixed in some Haskell syntax there. And yes, return type is inferred.

There are two reasons for there not being explanations in the README:

1. I foolishly thought it would be obvious.

2. I wanted to focus on the implementation, not the language itself.

In any case, I've added them now, thanks.