[Jtsummers]

> > Why does python have to be slow?

> Because the language's semantics promise that a bunch of insane stuff can happen at any time during the running of a program, including but not limited to the fields of classes changing at any time.

You originally claimed Python is slow because of its semantics and then compare later to CL. CL has a very similar degree of dynamism and remains fast. That's what I'm saying makes for a poor comparison.

CL is a demonstration that Python, contrary to your initial claim, doesn't have to forfeit dynamism to become fast.

[lispm]

> CL has a very similar degree of dynamism and remains fast.

But not the dynamic parts remain "really" fast. Common Lisp introduced very early a lot of features to support optimizing compilers -> some of those reduce "dynamism". Code inlining (-> inline declarations), file compiler semantics, type declarations, optimization qualities (speed, compilation-speed, space, safety, debug, ...), stack allocation, tail call optimization, type inferencing, ...

[eigenspace]

I think you're missing the point. Common Lisp is very dynamic yes, but it was designed in a very careful way to make sure that dynamism does not make an optimizing compiler impossible. That is not the case for Python.

Not all dynamism is the same, even if the end result can feel the same. Python has a particularly difficult brand of dynamism to deal with.