A lightweight (~5000 LOC) Python interpreter for game engines

I&#x27;ve been waiting a long time for MicroPython to become usable as an embedded script interpreter -- it can&#x27;t be run asynchronously [1] so scripts can&#x27;t do waits (aside from that, MicroPython is amazingly full-featured). CPython can&#x27;t either, which is why the Stackless Python fork was created, which is used in games such as EVE Online. But that&#x27;s far too heavy for my tastes.<p>So I was hoping that PocketPy could do that, but after looking around I can&#x27;t find any suggestion it&#x27;s possible, and the API looks very sparse. I&#x27;m very happy to see a new Python interpreter built for embedding, but I can&#x27;t use it. Maybe it can be added easily enough. Keep it up!<p>If you want to see a scripting language designed from the ground up for embedding, Lua and Squirrel IMO have the most complete APIs (though not the most efficient or easy to use) [2][3], and LuaJIT has even better lua&lt;-&gt;C bridging. I&#x27;ve looked at the APIs of many other small scripting languages, and haven&#x27;t found any others that can do everything that these can.<p>[1] <a href="https:&#x2F;&#x2F;github.com&#x2F;micropython&#x2F;micropython&#x2F;issues&#x2F;3619">https:&#x2F;&#x2F;github.com&#x2F;micropython&#x2F;micropython&#x2F;issues&#x2F;3619</a><p>[2] In particular <a href="https:&#x2F;&#x2F;www.lua.org&#x2F;manual&#x2F;5.4&#x2F;manual.html#4.5" rel="nofollow">https:&#x2F;&#x2F;www.lua.org&#x2F;manual&#x2F;5.4&#x2F;manual.html#4.5</a><p>[3] <a href="http:&#x2F;&#x2F;squirrel-lang.org&#x2F;squirreldoc&#x2F;reference&#x2F;embedding_squirrel.html" rel="nofollow">http:&#x2F;&#x2F;squirrel-lang.org&#x2F;squirreldoc&#x2F;reference&#x2F;embedding_squ...</a>

Nice idea, as python is much easier to write code for than lua so should fit game scripting well.<p>But, the examples are not the kinds of things that I would care about before trying to put this into a game engine. It needs a different set of examples.<p>* How hard is it to call into a C function from a hook in the py code?<p>* How hard is it to wrap &#x2F; unwrap values from their py representation to C?<p>If you want people to <i>embed</i> the interpreter into an engine then show that it is clean&#x2F;easy to do the embedding, rather than showing that the interpreter can execute code. I would assume that it executes python, but need to know how well it embeds.

So is this a clean reimplementation? Given how small this is it probably is.<p>Which means this is not Python but a language that is syntax-compatible (&quot;Python-like&quot;). To prove compatibility something like a (very) extensive set of compatibility tests would have to be written and mentioned in the README. Otherwise it&#x27;s a minefield of subtle semantic differences.

What&#x27;s the performance like compared to Lua? Since Lua is the standard here, this feels like nonstarter unless the performance is similar, even with the friendlier python syntax.

If the author comes around, first of all congratulations on what seems like a really cool project. Second, I am curious as to whether the lack of &#x27;star unpack&#x27; is due to any real blocker, or more of a &#x27;not done yet&#x27;&#x2F;&#x27;not prioritized&#x27;?

How does this compare to tinypy? [1] <a href="http:&#x2F;&#x2F;www.tinypy.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.tinypy.org&#x2F;</a>

How is this on the homepage twice with no comments and less than 10 votes?

There&#x27;s not only the question of why use this over Lua, but why use this over many compile-to-lua languages, providing a great range of syntax and typing features.

I wonder how it compares with MicroPython?

The demo is fun to play with: <a href="https:&#x2F;&#x2F;blueloveth.github.io&#x2F;pocketpy&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blueloveth.github.io&#x2F;pocketpy&#x2F;</a><p>It uses <a href="https:&#x2F;&#x2F;blueloveth.github.io&#x2F;pocketpy&#x2F;lib&#x2F;pocketpy.wasm" rel="nofollow">https:&#x2F;&#x2F;blueloveth.github.io&#x2F;pocketpy&#x2F;lib&#x2F;pocketpy.wasm</a> which is 766.66 kB - transferred compressed as 240.72 kB

Wow, this is excellent! I love the fact that it is just in 5K lines. I have a few questions!<p>1. What were your motivations for building this?<p>2. Did you eval any similar projects before writing this one?<p>3. Can this be compiled to WASM and used in the browser? edit: I see that it already supports WASM!<p>4. I didn&#x27;t see this on the README, but does it support IO (either disk or network)?<p>5. I noticed you linked to byterun. Does this also implement a VM similar to Python? Can I run the bytecode produced from CPython in the pocketpy VM? If so, are there any reasons for that? I thought writing an independent implementation would be faster&#x2F;easier than a compatible one.<p>6. Any plans on adding type annotations?

Hmm duplicate of <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=34702386" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=34702386</a> maybe I should text @dang to merge...

Hmm, wish this had been built as a PocketPy -&gt; LLVM compiler. While the compiler might not have been lightweight, the final emitted binaries would have been superfast.

*interpreter for a small Python subset<p>Should be expected from the size of codebase but should also be clearly mentioned. And this isn&#x27;t about just lacking Python&#x27;s modules. Plain language features are also not there. For example reversing a string with &quot;abcd&quot;[-1::-1] doesn&#x27;t work. Now there&#x27;s a features list on README, but not sure whether this is meant to be the comprehensive list this subset has or just a TODO.

This is neat! I assume this is Python 3?<p>Still looking for a replacement for the excellent Jython project [1] on the JVM, which has been fantastic for adding scripting to Java&#x2F;Scala based projects, but sadly stuck on Python 2.7. I wonder if this could be bolted onto or run inside a JVM somehow (perhaps the WebAssembly version?)<p>1: <a href="https:&#x2F;&#x2F;www.jython.org&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.jython.org&#x2F;</a>

I thought that &quot;weight&quot; generally referred to less resource usage (RAM primarly, cpu second) and loc weren&#x27;t part of those resources.<p>Was I wrong?

I&#x27;d like to give the WASM build a try

Great project!!<p>I was trying to build my own python interpreter to my project and this saved me a lot of work!<p><i>super nice-to-have ask:</i> could you replace the is_prime test on the README from range(2,x) to range(2,int(math.sqrt(x)))?

impressive work! i suppose it implements a subset and not the full language? would be nice to see some benchmarks. everyone claims super fast nowadays. i have no doubt though, since it&#x27;s cpp.

Why not lua though?

an i for an i is an i in range