[kazinator]

With declarations which are promises from the programmer to the compiler (I promise this is true, on penalty of undefined behavior), you can fix a lot of "stupid dynamic".

Python could have a declaration which says, "this function/module doesn't participate in anything stupidly dynamic, like access to parent locals". If it calls some code which tries to access parent locals, the behavior is undefined.

That's kind of a bad thing because in Lisp I don't have to declare anything unsafe to a compiler just to have reasonably efficient local variables that can be optimized away and all that.