Comment by deltasevennine

Then your comment doesn't make sense to me. If you designed programs in haskell then you designed them using concepts from category theory.

Category theory isn't just about how haskell works. You use it to design your programs. Haskell is basically a category theory framework.

I would say you didn't get very far then if you didn't come out of learning haskell with the realization of how you design programs with CT.