How to make a fast dynamic language interpreter

(zef-lang.dev)

116 points | by pizlonator 5 hours ago

4 comments

  • grg0 4 hours ago
    Interesting, thanks for sharing. It is a topic I'd like to explore in detail at some point.

    I also like how, according to Github, the repo is 99.7% HTML and 0.3% C++. A testament to the interpreter's size, I guess?

    • pizlonator 3 hours ago
      I committed the statically generated site, which is wastefully large because how I generate the code browsers

      But yeah the interpreter is very small

  • tiffanyh 2 hours ago
    I see Lua was included, wish LuaJIT was as well.
    • pizlonator 2 hours ago
      I bet LuaJIT crushes Zef! Or rather, I would hope that it does, given how much more engineering went into it

      There are many runtimes that I could have included but didn’t.

      Also, it’s quite impressive how much faster PUC Lua is than QuickJS and Python

      • raincole 1 hour ago
        Because QuickJS is really slow. Don't be fooled by the name. It's almost an order of magnitude slower than node/v8.

        (I suppose the quick in QuickJS means "quick for a pure interpreter without JIT compilation or something...)

        • pizlonator 1 hour ago
          based on this data, it’s probably slower than JSC’s or V8’s interpreter

          So like that’s wild

      • zephen 1 hour ago
        > it’s quite impressive how much faster PUC Lua is than QuickJS and Python

        Python's execution time is mostly spent looking up stuff. I don't think lua is quite as dynamic.

        • pizlonator 1 hour ago
          Lua is way more dynamic
          • zephen 1 hour ago
            I suppose it depends on where you are looking for dynamicity. In some ways, lua is much more laissez faire of course.

            But in Python, everything is an object, which is why, as I said, it spends much of its time looking things up. And things like bindings for closures are late, so that's more lookups as well.

            In lua, many things aren't objects, and, for example, you can add two numbers without looking anything up. Another issue, of course, when you do that, is that you could conceivably overflow an integer, but that can't happen in Python either.

            The Python interpreter has some fast paths for specific object types, but it is really limited in the optimizations it can do, because there simply aren't any unboxed types.

  • boulos 2 hours ago
    How's your experience with Fil-C been? Is it materially useful to you in practice?
    • pizlonator 2 hours ago
      I’m biased since I’m the Fil.

      It was materially useful in this project.

      - Caught multiple memory safety issues in a nice deterministic way, so designing the object model was easier than it would have been otherwise.

      - C++ with accurate GC is a really great programming model. I feel like it speeds me up by 1.5x relative to normal C++, and maybe like 1.2x relative to other GC’d languages (because C++’s APIs are so rich and the lambdas/templates and class system is so mature).

      But I’m biased in multiple ways

      - I made Fil-C++

      - I’ve been programming in C++ for like 35ish years now

      • vlovich123 1 hour ago
        I’m curious. Given the overheads of Fil-C++, does it actually make sense to use it for greenfield projects? I like that Fil-C fills a gap in securing old legacy codebases, I’m just not sure I understand it for greenfield projects like this other than you happen to know C++ really well.
        • pizlonator 1 hour ago
          It made sense because I was able to move very quickly, and once perf became a problem I could move to Yolo-C++ without a full rewrite.

          > happen to know C++ really well

          That’s my bias yeah. But C++ is good for more than just perf. If you need access to low level APIs, or libraries that happen to be exposed as C/C++ API, or you need good support for dynamic linking and separate compilation - then C++ (or C) are a great choice

          • vlovich123 17 minutes ago
            Hmmm… I did about 20+ years of C++ coding and since I’ve been doing Rust I haven’t seen any of these issues. It has trivial integrations with c/c++ libraries (often with wrappers already written), often better native libraries to substitute those c++ deps wholesale, and separate compilation out of the box. It has dynamic linking if you really need it via the C ABI or even rlib although I’ll grants the latter is not as mature.

            The syntax and ownership rules can take some getting used to but after doing it I start to wonder how I ever enjoyed the masochism of the rule of 5 magic incantation that no one else ever followed and writing the class definition twice. + the language gaining complexity constantly without ever paying back tech debt or solving real problems.

  • Futurmix 3 hours ago
    [flagged]