I doubt it would have a JIT a long time ago. Thing is, people have been making JIT compilers for Python for a long time now, but the semantics of the language itself is such that it's often hard to benefit from it because most of the time isn't in the bytecode interpreter itself, it's dispatching things. People like comparing Python to JavaScript, but Python is much more flexible - all "primitive" types are objects can be subclassed for example, and even basic machinery like attribute lookups have a bunch of customization hooks.
So the problem is basically that a simple JIT is not beneficial for Python. So you have to invest a lot of time and effort to get a few percent faster on a typical workload. Or you have to tighten up the language and/or break the C ABI, but then you break many existing popular libraries.
Those people usually overlook the history of Smalltalk, Self and Common Lisp, which are just as dynamic if not more, due to image use, debugging and compilation on the fly where anything can be changed at any time.
For all its dynamism, Python doesn't have anything closer to becomes:.
I would say that by now what is holding Python back is the C ABI and the culture that considers C code as Python.
> People like comparing Python to JavaScript, but Python is much more flexible - all "primitive" types are objects can be subclassed for example, and even basic machinery like attribute lookups have a bunch of customization hooks.
Most of the time, people don't use any of these customisations, don't they?
So you'd need machinery that makes the common path go fast, but can fall back onto the customised path, if necessary?
Descriptors underpin some common language features like method calls (that's how `self` gets bound), properties etc. You can still do it by special casing all those, and making sure that the way you implement all those primitives works exactly as if it used descriptors, sure. But at this point it's not exactly a simple JIT anymore.
So the problem is basically that a simple JIT is not beneficial for Python. So you have to invest a lot of time and effort to get a few percent faster on a typical workload. Or you have to tighten up the language and/or break the C ABI, but then you break many existing popular libraries.