Nuprl
Nuprl
A system for interactive creation of formal mathematics,including definitions and proofs. It has an extremely richtype system, including dependent functions, products, sets,quotients and universes. Types are first-class citizens.It is built on Franz Lisp and Edinburgh ML.
["Implementing Mathematics in the Nuprl Proof DevelopmentSystem", R.L. Constable et al, P-H 1986].