Juha Arpiainen has implemented his own proof checker in Common Lisp called Bourbaki and Marnix Klooster has coded a proof checker in Haskell called Hmm.
Both Juha Arpiainen and Marnix Klooster created their own proof checkers, one for the programming language Common Lisp (Bourbaki) and the other for the programming language Haskell (Hmm).