1. Hask has Haskell types as objects, and functions between them as morphisms. "a" is a type, "b" is a type, and "a -> b" is an arrow between them. 2. Haskell

1. Hask has Haskell types as objects, and functions between them as morphisms. "a" is a type, "b" is a type, and "a -> b" is an arrow between them. 2. Haskell cannot model (the entirety of) category theory. Everything in Haskell is in Hask, and the only way to get to an entirely different category (say Set) is on paper. This great talk gives some insight into the issue: https://vimeo.com/67174266 https://vimeo.com/67174266