Common Lisp at the language level is similar to Python or Ruby as it has strong dynamic typing. One difference is that CL has optional type declarations which (

Common Lisp at the language level is similar to Python or Ruby as it has strong dynamic typing. One difference is that CL has optional type declarations which (in contrast to Python's take on the same thing) are really specified as declaring types but what the implementation should do with that information is completely implementation-defined with using it to implement C-style weak static typing being completely legitimate and for some time even popular.