> the type... > x -> a x y -> z y > ...tells me nothing. I am guessing that you wouldn’t see a type signature like this in a real codebase. The type signatur

> the type... > x -> a x y -> z y > ...tells me nothing. I am guessing that you wouldn’t see a type signature like this in a real codebase. The type signature of Data.HashMap.Strict.lookup is (Eq k, Hashable k) => k -> HashMap k v -> Maybe v which is quite a bit more readable. You can even search Hoogle for x -> HashMap x y -> y and find it, try it! https://hoogle.haskell.org/?hoogle=x%20-%3E%20HashMap%20x%20y%20-%3E%20y https://hoogle.haskell.org/?hoogle=x%20-%3E%20HashMap%20x%20...