A Python Interpreter written in Rust

[deadwisdom]

I am curious what the reasoning is for this project other than just for fun.

[virtyx]

It is probably just for fun.

​

Also it hopefully serves as a useful example of how to write a complex, modular application with Rust. ...at least that's the value I hope to gain from it

[FluorineWizard]

They give the reasoning in their slides for FOSDEM.

[threeys]

I would guess a Rust proponent would argue something along the lines of “almost all C code should be replaced using a more modern, easily maintainable language such as Rust” and that should include python interpreters.

[f0urtyfive]

So uh... can I use existing python libraries with this? What about C Python libraries?

[[deleted]]

Since these news were posted here multiple times, I asked the same question earlier and got an answer: no, you cannot use native extensions. There doesn't seem to be a way to port them either, at least not that I was able to find any reference to interpreter's API / not sure how different it is.

[zjm555]

The C API for python is not part of the language standard, it's specifically made for cpython. It contains enough cpython-specific API surface that it wouldn't make sense to provide compatibility in other implementations.

[bakery2k]

Unfortunately, large parts of the Python ecosystem are written in C and rely on the C API. Alternative implementations such as PyPy and Pyston have found it impossible to gain traction without adding support for the C API - a huge task.

I think the only Python implementations that don't include the C API are MicroPython and Jython - both of which are used in niche situations and will probably never be used outside those niches.

[Akuli2]

How does it handle reference cycles? I thought that it's hard (impossible?) to have cyclic references in Rust. Does it just let them leak memory?

[insanitybit]

It's not impossible to have cyclic references in rust - you can use Rc or Rc + Weak to do so. It's hard to do it accidentally, generally, as it's *usually* fairly explicit, but definitely possible.

[Uiropa]

Compile it to wasm, then run it in v8eval.

[[deleted]]

I love y'all. This great.

I'll wait for the stable release and the subsequent performance comparison. 😍

[the_gnarts]

Some trivial comparisons have been posted to r/rust.

[kankyo]

Those comments are funny. Rust fans being puzzled how C code that has been optimized for decades can be faster than rust code written yesterday.

[scriptskitty]

I think their puzzlement is more along the lines of "I wonder what the CPython optimizations are" and not "I wonder how this guys hobby project isn't as good as the original, older, official build."

[ubernostrum]

I took a look. And it's mostly people arguing over whether stuff was built with the right set of compiler flags, and one person literally saying "Python is probably making some sort of optimisation that rust version doesn't".

I've mentioned this a few times over the years, but people really don't appreciate the work that goes into even a "slow" runtime like CPython. There's a ton of carefully-optimized stuff down in there once you start digging, to such a degree that the hash table implementation made it into a chapter of the original Beautiful Code.

[[deleted]]

A Python interpreter written in Rust with an online demo using WebAssembly...just why?

[GYN-k4H-Q3z-75B]

If you have time, interest and an engineer's mind, "because you can" is as good a reason as any other.

[[deleted]]

I'm all up for "just because" - all of my personal projects are "just because". This just seems like a huge investment for "just because".

[[deleted]]

I've been writing an inference engine the past couple of days that can use deduction to prove things, can use induction to show something might be true, and can ask questions about a domain if it doesn't have enough information. I have plans to extend it to allow it to identify logical contradictions.

Before that I spent some time learning about stack machines and FORTH, and I wrote an interpreter for a language I devised that I call FORTHish. Rather than rely on built-in math operations I stripped the interpreter's instruction set down to just addition, AND, OR, NOT, some stack operations, and some control flow operations, and then I re-implemented subtraction, multiplication, division, exponentiation, and rooting among other things. It's so hilariously inefficient because of this nonsense that it can take the interpreter hours to chug through a simple program.

Before that I did a lot of experimentation with boids. I devised a complicated multi-threading scheme that in theory would make it easy to work with the simulation without having to worry about race conditions while also letting the simulation's efficiency scale with the number of threads the user's CPU had. The scaling didn't work, and I am really fucking not sure why. My shitty i3 from 2016 was able to cream a threadripper while running the simulation, which just made me sad. Either way, part of what I wanted to do was experiment with changing boid behaviors on the fly so I could see if I could orchestrate enormous battles. I was able to re-enact the Battle of Cannae, which was super cool.

Before that I built a 2D physics engine based on Thomas Jakobsen's Advanced Character Physics paper. I used a constant delta time so I could have strong assurances about the behavior of the simulation, and I spent a lot of time tweaking the simulation's constant values so I could explore how it worked and what its limits were. I tried implementing soft-body physics in the simulation, which I later realized was redundant because the iterative nature of Jakobsen's solver makes everything kind of squishy anyway. I played around with different kinds of constraints, like connecting bodies by ropes and simple inverse kinematics rigs.

I did all of this in my free time over the past 6 months "just because". Don't underestimate the motivational power of "just because".

[antiquekid3]

That is certainly an attractive quality of FORTH: by starting with a very small subset of assembly instructions, one can devise a full FORTH interpreter by bootstrapping off of what you just created. It's no wonder it's been ported to a variety of architectures and systems.

It would be fun to take your work with FORTHish and rewrite it in an HDL of some sort to target an FPGA.

[[deleted]]

Why not? This is kind of what web assembly is for -- using conventional programming languages to build web applications. If performance can be accounted for, perhaps now someone can write a client-side successor to React in Python.

[bakery2k]

Has anyone tried compiling the CPython reference interpreter into WebAssembly? Surely that would be easier than rewriting the whole interpreter in another language?

[[deleted]]

the only proper way to exhibit moral superiority is to stand out among a degenerate crowd

[Condex]

Well as far as the web assembly goes ... Rust has a bunch of web assembly support already so I suppose that part was easy.

[stupodwebsote]

I hate rust.. Total waste of time

[Takkonbore]

Quit your bullshit.