I believe the answer to your question lies in what Tel said: https://news.ycombinator.com/item?id=8671889 https://news.ycombinator.com/item?id=8671889 If you

I believe the answer to your question lies in what Tel said: https://news.ycombinator.com/item?id=8671889 https://news.ycombinator.com/item?id=8671889 If you avoid recursion and use explicit state passing and create an API with combinators hiding the state passing plumbing you get very fast Haskell. I believe many people never get to the "write combinators to hide plumbing" part and assume to get very fast Haskell they have to duplicate the explicit state passing everywhere.