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Comment by _ZeD_ | Hacker News Reader

keep in mind that, apart from the money throw at js runtime interpreters by google and others, there is also the fact that python - as a language - is way more "dynamic" than javascript.

Even "simple" stuff like field access in python may refer to multiple dynamically-mapped method resolution.

Also, the ffi-bindings of python, while offering a way to extend it with libraries written in c/c++/fortran/... , limit how freely the internals can be changed (see the bug-by-bug compatibility work done for example by pypy, just to name an example, with some constraint that limit some optimizations)

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> python - as a language - is way more "dynamic" than javascript

Very true, but IMO the existence of PyPy proves that this doesn't necessarily prevent a fast implementation. I think the reason for CPython's poor performance must be your other point:

> the ffi-bindings of python [...] limit how freely the internals can be changed

> Very true, but IMO the existence of PyPy proves that this doesn't necessarily prevent a fast implementation.

PyPy pays for this by having slower C interaction.

See Smalltalk, Self and Common Lisp for highly dynamic languages with good enough JIT, the first two having their research contributed to Hotspot and V8.

genuinely curious, doesn't JS's proxy objects and prototype-based MRO have a similar performance impact in theory?

Yeah, I don't see how Python is fundamentally different from JavaScript as far as dynamicism goes. Sure Python has operator overloading, but JavaScript would implement those as regular methods. Pyrhon's init & new aren't any more convoluted than JavaScript's constructors. Python may support multiple inheritance but method and attribute resolution just uses the MRO which is no different than JavaScript's prototype chain.

Urban myths.

Most people that parrot repeat Python dynamism as root cause never used Smalltalk, Self or Common Lisp, or even PyPy for that matter.

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