Some Lisp implementations (like SBCL) also do that blending, although they can statically catch some integer range violations too. For example if you declare a

Some Lisp implementations (like SBCL) also do that blending, although they can statically catch some integer range violations too. For example if you declare a variable to be an (integer 50 100) and try to assign a literal 30 to it, you'll get a compile-time warning in SBCL: ; Constant 30 conflicts with its asserted type (INTEGER 50 100). But in many other cases it'll generate a runtime check instead, because the static type checking is basically best-effort.