[DougBTX]

> How does a language benefit from not having the option to compile it? What restrictions does the requirement to be able to produce a machine-code executable place on it?

“Compiled” is being used as a short-hand for “compiled with optimisations”, so yes, an unoptimised build wouldn’t count here.

The design decision is around when (between the code being written and being run) is the final decision made about what exact code will run. If that is known really early (static types, no dynamic dispatch) then optimisations can be made early too. If it is really late (polymorphic methods, support for redefining types etc) then optimisation needs to run very quickly (“just in time”) or not at all.

If you want to go deeper on this, look at performance optimisation in Julia. It has the same LLVM backend as C/Rust, so can use all the same optimisations, but it is arguably a more dynamic and easier to use language than Python, so when and how optimisations apply really depends on how the code itself is written. As a bonus, it has some great tooling to see how changes to the code impact performance.