i don't have enough haskell in my head yet to totally get this article but it's from the current emacs maintainer, it has some interesting explanatory links, and talks about recursion and parsing and all that nonsense with a really interesting application to parsing the nix language. specifically the heading "reducing programs to test cases" reminded me of a comment @witty-crayon-22786 made on github about integration tests as `@rule`s which i still think is super legit