Show HN: Bolt – A super-fast, statically-typed scripting language written in C

82 beariish 29 8/10/2025, 5:53:09 PM github.com ↗
I've built many interpreters over the years, and Bolt represents my attempt at building the scripting language I always wanted. This is the first public release, 0.1.0!

I've felt like most embedded languages have been moving towards safety and typing over years, with things like Python type hints, the explosive popularity of typescript, and even typing in Luau, which powers one of the largest scripted evironments in the world.

Bolt attempts to harness this directly in the lagnauge rather than as a preprocessing step, and reap benefits in terms of both safety and performance.

I intend to be publishing toys and examples of applications embedding Bolt over the coming few weeks, but be sure to check out the examples and the programming guide in the repo if you're interested!

Comments (29)

perlgeek · 1h ago
I like 99% of this, and the thing I don't like is in the very first line of the example:

> import abs, epsilon from math

IMHO it's wrong to put the imported symbols first, because the same symbol could come from two different libraries and mean different things. So the library name is pretty important, and putting it last (and burying it after a potentially long list of imported symbols) just feels wrong.

I get that it has a more natural-language vibe this way, but put there's a really good reason that most of the languages I know that put the package/module name first:

    import packageName.member; // java
    from package import symbol; # python
    use Module 'symbol'; # perl
    
With Typescript being the notable exception:

    import { pi as π } from "./maths.js";t
jasonjmcghee · 12m ago
Also autocomplete.

Though I almost never manually type out imports manually anymore.

bbkane · 16m ago
I really like the way Elm does it, from "wide" (package) to "narrow" (symbol). I suspect this also helps language server implementation.

See https://guide.elm-lang.org/webapps/modules (scroll down to "Using Modules") for examples

beariish · 1h ago
Do you think approaching the way typescript does it for Bolt is a reasonable compromise here? Bolt already supports full-module renames like

    import math as not_math
So supporting something along the lines of

    import abs as absolute, sqrt as square_root from math
Would be farily simple to accomplish.
haberman · 1h ago
I love the concept -- I've often wished that lean languages like Lua had more support for static typing, especially given the potential performance benefits.

I also love the focus on performance. I'm curious if you've considered using a tail call design for the interpreter. I've found this to be the best way to get good code out of the compiler: https://blog.reverberate.org/2021/04/21/musttail-efficient-i... Unfortunately it's not portable to MSVC.

In that article I show that this technique was able to match Mike Pall's hand-coded assembly for one example he gave of LuaJIT's interpreter. Mike later linked to the article as a new take for how to optimize interpreters: https://github.com/LuaJIT/LuaJIT/issues/716#issuecomment-854...

Python 3.14 also added support for this style of interpreter dispatch and got a modest performance win from it: https://blog.reverberate.org/2025/02/10/tail-call-updates.ht...

beariish · 1h ago
I did experiment with a few different dispatch methods before settling on the one in Bolt now, though not with tailcalls specifically. The approach I landed on was largely chosen cause it in my testing competes with computed goto solutions while also compiling on msvc, but I'm absolutely open to try other things out.
summerwant · 1h ago
I see lua, do you know terralang?
cookiengineer · 1h ago
If functions don't have a return signature, does that mean everything must be satisfied in the compilation step?

What about memory management/ownership? This would imply that everything must be copy by value in each function callsite, right? How to use references/pointers? Are they supported?

I like the matchers which look similar to Rust, but I dislike the error handling because it is neither implicit, and neither explicit, and therefore will be painful to debug in larger codebases I'd imagine.

Do you know about Koka? I don't like its syntax choices much but I think that an effect based error type system might integrate nicely with your design choices, especially with matchers as consumers.

[1] https://koka-lang.github.io/koka/doc/index.html

zygentoma · 24m ago
Oh, not OP, but I love Koka. I should play around with it again thanks for reminding me!
MobiusHorizons · 2h ago
FYI "the embedded scene" is likely to be interpreted as "embedded systems" rather than "embedded interpreters" even by people who know about embedded interpreters, especially since all the languages you give as an example have been attempted for use on those targets (micropython, lua, and even typescript)
beariish · 2h ago
That's a good point, thank you. I've made a small edit to clarify.
k__ · 3m ago
Awesome.

Is it deterministic like Lua?

freeopinion · 41m ago
I see your benchmarks compare against other interpreted languages "in its class".

We read here a couple days ago about Q which is compiled. Bolt claims to "plow through code at over 500kloc/thread/second". Q claims to compile in milliseconds--so fast that you can treat it like a script.

Bolt and Q are both newborns. Perhaps you could include each other in your benchmarks to give each other a little publicity.

themonsu · 3h ago
Looks cool, but please can we stop naming things ”bolt”
Fraterkes · 56m ago
Really cool! Roughly how much memory does it take to include it in an engine? Also I'm really interested in the process of creating these really fast scripting languages, have you written anything about how you wrote Bolt?
beariish · 54m ago
Bolt's memory usage in most cases hovers right around Lua 5.4/Luau in my own testing, but maybe I should include a few memory benchmarks to highlight that more. It does notably have a higher memory overhead during compilation than other languages in this class though.

As for writeups, I'm working on putting out some material about the creation of Bolt and my learnings now that it's out there.

Forgret · 52m ago
It looks cool, I wish you luck in developing the language. I liked your language and I hope it becomes popular someday.
kiririn · 1h ago
Nice, gives me Pawn vibes

(https://www.compuphase.com/pawn/pawn.htm)

grodriguez100 · 3h ago
Sounds very good, and I can see many use cases in embedded systems. But that probably requires 32-bit arm support. Is that planned ?
beariish · 3h ago
As of right now no - my primary target when developing this was realtime and games in particular since that's what I know best, but if there's a real target in embedded that's certainly something that could be explored.
Vandash · 1h ago
game dev for 15+ years here, love the first example on Github this is compiled right? cannot replace lua?
IshKebab · 1h ago
It's compiled in the same way that Lua is compiled. So yes, it can replace Lua.
beariish · 1h ago
Bolt is not compiled ahead of time, it's bytecode interpreted just like Lua
acron0 · 3h ago
If I was still writing games I would be alllllll over this
eulgro · 2h ago
The question I ask myself when I see this kind of project is: how long are you willing to maintain it for?

My main concern about a new language is not performance, syntax, or features, but long term support and community.

brabel · 1h ago
The only way to have any idea of how long a language might be still around is to look at how long it's been already around. From this perspective , you can only use older languages. The benchmarks show that Lua (and the Luau and Lua+JIT variants) is actually very competitive, so I'd stick with one of those.
01HNNWZ0MV43FF · 2h ago
In the end, weight is a kind of strength, and popularity is a kind of quality. It looks promising but you can't expect long-term support until there's more contributors and users

At this point it is too early to know. Even JavaScript took like 20 years to catch on

thrance · 2h ago
Function return type inference is funny but I don't think it's that great of a feature. It makes it harder for a library's consumer to know how to properly use a function, and it also makes it harder for the maintainer to not break backwards compatibility inadvertently. Anyway, I'm all for experimenting.
beariish · 2h ago
There's nothing stopping a library author from explicitly annotating return types wherever a stable interface is important, the idea is more for smaller functions or callbacks to make use of this. Perhaps I'll make the examples clearer to reflect the intention.