Below, I have collected several examples of "uncanny" Haskell. These are things that may be surprising to those who have learned the language merely by doing.
Initially, I had written
hackage-fetch to see if there was
any use of
anywhere on Hackage. At the time, there was not, but this has changed due
gmpint package. As of
writing, it is not surprisingly the only use of co-(Elgot algebra)s on the entirety of Hackage.
You may have seen my post on co-(Elgot algebras),
in which I mentioned I had been using some exotic recursion schemes for my
gmpint package. I came across a similar example, this time for Mendler-style
recursion schemes. To my knowledge, it is the only published example of
a Mendler-style catamorphism.
I've been looking for an example of co-(Elgot algebra)s for quite some time, and
I came across a surprisingly nice example while working on my