A Lisp with a type system? Sounds like Common Lisp to me. SBCL (I'd say as close to a de facto standard as it gets) even has pretty good compile time type check

A Lisp with a type system? Sounds like Common Lisp to me. SBCL (I'd say as close to a de facto standard as it gets) even has pretty good compile time type checking. E.g. (defun foo (a b) (declare (type String a b)) (+ a b)) ; in: DEFUN FOO ; (+ A B) ; ; caught WARNING: ; Derived type of COMMON-LISP-USER::A is ; (VALUES STRING &OPTIONAL), ; conflicting with its asserted type ; NUMBER. ; See also: ; The SBCL Manual, Node "Handling of Types" ; ; compilation unit finished ; caught 1 WARNING condition The type checking is the main thing that drove me to switch from Scheme to CL in the first place, and I stuck around for the nice little things like restarts and continuable asserts.