But [Lisp] won't enforce those things at compilation time in the type system, because it doesn't have one. What Lisp implementation do you have in mind? I a

But [Lisp] won't enforce those things at compilation time in the type system, because it doesn't have one. What Lisp implementation do you have in mind? I ask because Common Lisp has type system that includes compile-time type checking. For example, SBCL: http://sbcl.org/manual/index.html#Handling-of-Types http://sbcl.org/manual/index.html#Handling-of-Types