We definitely intend on folks being able to use Luau outside of Roblox, and we know of a number of folks doing so quite successfully including Remedy Entertainment (Alan Wake 2), Digital Extremes (Warframe), GIANTS Software (Farming Simulator 25).

That being said, it has been historically hard to get major investment into work actively supporting growth of the language off-platform since our entire team is employed to work on the project by Roblox. We are nevertheless changing this though, and investing in the language outside of the platform. As some folks have already mentioned here, we have a general-purpose standalone runtime that we're developing called Lute that's focused on using Luau outside of Roblox to write general-purpose programs, and we're building a whole suite of Luau-programmable developer tools for the language atop it.

It takes time to build things, and the Luau ecosystem is definitely still very young as you've noted, but it's something that we care a lot about and are investing in considerably going forward. We 100% believe that the best thing for the health of the language and the ecosystem is to support more diverse users and more diverse use-cases.

I use Luau with my Unity game for all gameplay code (60k+ loc so far). I agree the docs could be improved, especially for custom integrations. The new type system + LSP aren't great together yet either, and I've been a little worried about the direction since zeux left the team.

But otherwise I really like it. My Luau code hot reloads almost instantly while the game is running, and my C++ project compiles quickly when I update it. I like that it provides sandboxing if you want to support modding. And there's an active community of people on the official Discord, which is better than nothing.

Thanks for sharing your experience. I'm curious why it would cause your project to compile slower though? It's a scripting language, so you don't need to compile anything, right? Do you mean compiling the Luau VM itself?

There's another standalone Luau runtime called Lune: https://github.com/lune-org/lune

there's a slightly more mature runtime for Luau developed already:

https://github.com/lune-org/lune

i use it for build scripts and automating tasks for Roblox place files, it's pretty good for my use-case

Lua (and to a somewhat lesser extent Luau) are small in terms of the learned surface of the value language, not necessarily in terms of lines of code. That being said, any runtime use of the language needn't depend on Analysis, which is the biggest compilation unit by far.

Probably also worth mentioning that Analysis currently contains two full type system implementations because we've spent the better part of the past three years building a new type system to address a lot of the fundamental limitations and architectural issues that we'd run into after years of working on the original one. The new one is not without issues still, but is definitely very usable, and gets better and better every week. At some point in the future, we will clip the old one altogether, and that'll shave off some 30,000 lines of code or something.

I fully agree. Lua and Luau are impressive, sure, but they are not really "small" or "simple", in my view. I don't think the complexity is unavoidable however. There are many programming languages that are much simpler, but at the same time very expressive. I'm working on one of them currently named "Bau" [1], and I started working on a Lua-inspired VM [2] for a subset of this language. There are many languages like mine, most of them incomplete and not really popular, discussed in [3].

[1] https://github.com/thomasmueller/bau-lang [2] https://github.com/thomasmueller/bau-lang/blob/main/src/test... [3] https://www.reddit.com/r/ProgrammingLanguages/

To further elaborate, here's a more detailed breakdown of tokei's line counts for each of the directories you list + the CodeGen directory:

- Analysis: 62821 lines of C++ code, 9254 lines of C headers

- Ast: 8444 lines of C++, 2582 lines of C headers

- CodeGen: 21678 lines of C++, 4456 lines of C headers

- Compiler: 7890 lines of C++, 542 lines of C headers

- VM: 16318 lines of code, 1384 lines of C headers

Compare to Lua 5.1, which tokei says has 11104 lines of C and 1951 lines of C headers in the src/ directory.

Arseny Kapoulkine is an amazing engineer. Highly recommend following his blog or social media. Other than working on luau and the rendering engine at Roblox, he's also responsible for meshoptimizer which if you're in graphics you've most definitely heard of, and volk, which now comes packaged with the Vulkan SDK.

Teal compiles teal files into plain Lua just like TS does for JS. So all the advantages and disadvantages apply.

Luau is a backwards compatible superset of Lua that comes with it's own performance-tuned runtime. It offers more than just gradual typing.

So they are very different things. You can use Teal in cases when you don't control the runtime. Like write a Love2d game or your neovim config in it. Anywhere where Lua runs, you can use teal.

On the other hand Luau can offer superior developer experience because you don't have a separate compile step. They can do a lot more things that are impossible with teal as they have their own runtime and types do not get erased by compiling.

Luau isn't "Lua but with types," but rather a language in the Lua family that has grown a powerful gradual type system with a _ton_ of type inference (this is in contrast to e.g. TypeScript which takes the approach more of "add annotations to get benefits"), as well as a growing number of additions to the language that we believe make it a more pleasant developer experience to use. We're very focused on preserving the general ability to embed the language readily and with low costs to binary size and so forth, but we're less ruthlessly committed to the language's simplicity (for both better and worse). Overall, the goal is an embeddable language related to Lua with a focus on developer tooling and a positive developer experience such that people actually want to (and enjoy) build(ing) software in the language, rather than e.g. build large C projects and then expose them to Lua.

Teal transpiles to Lua, but Luau is a fork of Lua. Luau can implement wider ranging changes, like improving interpreter performance and security or adding syntactic sugar.

Roblox has a market cap near $100B and has multiple developers working full-time on Luau.

It's hard to get reliable numbers on this but I believe 5.1 and 5.2 are both more popular than 5.4 which has been out for five years now. And I don't think 5.3 ever surpassed either of them. I'm not sure about luajit it gets a lot of attention but I don't see it around all that much.

I think it's even worse than that, luau and luaJIT have evolved in different directions than the official lua project, such that they are now all sublty incompatible with each others. They all branch from lua 5.1 but it feels like there isn't an offical standard anymore.

Luau already has Luau Language Server which works extremely well for vscode w/ nvim & zed support as well. It surfaces Luau's own diagnostics w/ autocomplete, strict type checking, etc., leading to a better DX (for me) than using Ruby or Python. I primarily use Luau as a shell scripting & general purpose programming language w/ my own runtime (ala node is to js) called seal. Many Roblox devs use a different (much more popular) runtime called Lune for Roblox CI/CD, unit & integration testing, etc.

Like a LLVM but for type systems instead of compilation / interpreters / JIT. I don’t see why that couldn’t work.

My thinking in this space has always started from a type inferred MetaLanguage but starting from a dynamic language does enable some interesting options. I tend not to touch dynamic languages, even going so far as to use transpilers, but I definitely would be more open to the idea of working with them if they had TypeScript level of gradual type checking and tool support. As you mention such a bidirectional transpiler would work I guess for things that don’t translate it could just give up and that’ll be part of the gradual typing aspect.

I would love to have TypeScripts type system on a Lua runtime, so I’ve been keeping an eye on Luau.

It already exists actually: https://github.com/TypeScriptToLua/TypeScriptToLua.

I had a pretty good experience with it while trying out Love2D.

For all its success typescript demonstrates the downside of this approach. Like you said it's just difficult, and the end result of having every corner of the dynamic language expressible in the type system forces you into the most complex & novel type systems.

IMO a better approach is the one used by rescript and gleam. With a few careful restrictions of the target language you can fit it into a hindley-milner type system. These are extremely well understood, robust & usable, and give you a much smaller interface than the expansive turing complete one of TS.

I'm kind of surprised there's not an active project for a small ML language outputting lua code. I really wish gleam could pick it up as a third backend, it would be an amazing fit.

Luau was named Luau before Luau was a different language