Earlier quoted context omitted.
To the contrary. In CL some flexibility was given up (compared to other LISP dialects) in favor of enabling optimizing compilers, e.g. the standard symbols cannot be reassigned (also preserving the sanity of human readers). CL also offers what some now call 'gradual typing', i.e. optional type declarations. And remaining flexibility, e.g. around the OO support, limits how well the compiler can optimize the code.
But type declarations in Python are not required to be correct, are they? You are allowed to write def twice(x: int) -> int: return x + x print(twice("nope")) and it should print "nopenope". Right?
def twice(x: int) -> int:
if not isinstance(x, int):
raise TypeError("Expected x to be an int, got " + str(type(x)))
return x + x