Comment by eru
10 hours ago
> [...], it is a uniquely horrible slow language.
To be fair, Python as implement today is horribly slow. You could leave the language the same but apply all the tricks and heroic efforts they used to make JavaScript fast. The language would be the same, but the implementations would be faster.
Of course, in practice the available implementations are very much part of the language and its ecosystems; especially for a language like Python which is so defined by its dominant implementation of CPython.
You don't even need to go all V8, you could just build something like LuaJIT and get most of the way there. LuaJIT is like 10k LOCs and V8 is 3M LOC.
The real reason is that it is a deliberate choice by the CPython project to prefer extensibility and maintainability to performance. The result is that python is a much more hackable language, with much better C interop than V8 or JVM.
Fair! I guess I didn't mean language as such, but as used.
But a lot of the monkey-patching kind of things and dynamism of python also means a lot of those sorts of things have to be re-checked often for correctness, so it does take a ton of optimizations off the table. (Of course, those are rare corner cases, so compilers like pypy have been able to optimize for the "happy case" and have a slow fall-back path - but pypy had a ton of incompatibility issues and now seems to be dying).
Javascript has a lot of the same theoretical dynamism, yet V8 and WebkitCore were able to make it fast
Yes, with heroic effort. It's really a triumph of compiler / vm engineers over language designers.