[hgsgm]

Olah's blog entry is about types and algebra. We've had types and algebra for a long time distinct Category Theory, which is a further abstraction over algebraic structures.

A lot of computer programmers who never studied Abstract Algebra or Type Theory before think that all of that is Category Theory because Haskell is their first exposure to all that, and Category Theory is a big meme in Haskell, thanks to Monad.