They do, it's just not a priority. The PEP I linked (as well as most of the work of its author, Victor Stinner, in the last years) are motivated by JITing. The

They do, it's just not a priority. The PEP I linked (as well as most of the work of its author, Victor Stinner, in the last years) are motivated by JITing. There's also the "frame evaluation API" PEP [1], whose purpose is to allow pluggable evaluators in CPython without forking the entire interpreter, like Unladen Swallow had to. [1]: https://www.python.org/dev/peps/pep-0523/ https://www.python.org/dev/peps/pep-0523/