Nixlisp Lisp in Nix! Usage with import ./lisp.nix { a = null; }; eval (defun fib (n) (defun fib2 (a b n) (iff (lt n 2) b (def (next (plus a b)) (fib2 b next (minus n 1)))) (fib2 0 1 n)) (fib 60))