Moonshine – A lightweight Lua VM for the browser

by keyle • 12 years ago

106 70 12 years ago

binocarlos• 12 years ago

I'm loving how everything is moving to JS :)

Can someone explain why I might want to use Lua in a browser over JS? Does it have a fundamental feature that JS does not have?

Cool name btw!

swah• 12 years ago

I hate how everything is moving to JS :) I wish somehow there were multiple languages targetting a common bytecode.. but that won't happen for some reason I can't understand because I stopped in the middle of the dragon book.

chrisdevereux• 12 years ago

I don't think the dragon book will help unless the new edition has a section on how to organise a standards committee for your new language.

rayiner• 12 years ago

http://www.jwz.org/doc/worse-is-better.html

rubiquity2• 12 years ago

Personally, I feel that the biggest slap in the face to developers in the last decade is that V8 uses native code instead of byte code. In 10-20 years I hope we look back on Google's decision to do that and hate them for it.

ben0x539• 12 years ago

I think the point of contention is that there isn't really such a thing as a completely language-neutral bytecode, so nobody can agree on whose language-specific-js-replacement vm to ship.

Yorrrick• 12 years ago

It's simple. "Bytecode" is just a kind if encoding. The only thing it does is make programs marginally smaller and marginally quicker to decode. It's not enough to justify enormous switching costs. Let's talk about what functionality this new thing should have. That's where the high-value opportunities are. But, it's also where there's no easy consensus.

rational_indian• 12 years ago

It has 1 based indices, oh joy!

stcredzero6• 12 years ago

Yes, but you can code with 0 based indices just fine, when you need it. I know, because I've done it.

plorkyeran• 12 years ago

Coroutines, and Lua's metatables are more powerful than what can be done in ES5 (ES6 closes the gap a bit, and generators are equivalent to coroutines).

Lua is pretty much JS done right, which actually makes it a poor choice for something like this IMO. A program written in Lua is not going to be fundamentally different from the same program written in JS, and the problems introduced by using this (worse debugging experience etc.) are very likely to outweigh the benefits of avoiding JS's warts.

stcredzero6• 12 years ago

(worse debugging experience etc.)

How do you know? Maybe try this first? Apparently, there is a in-browser debugger you can activate just by including two files. This is theoretically a first-class debugger that doesn't even need source maps.

http://moonshinejs.org/how-to/debug-locally/

Were you assuming that Moonshine is a compiler targeting Javascript? It's actually a Lua bytecode VM.

anonymoushn• 12 years ago

Generators are equivalent to corourintes only as long as every single function you write is a generator and every single function call (to one of your own funcitons, anyway) is actually delegating to another generator. You can use a trampoline to make this less painful, but then you don't get to see your "real" call stack in the debugger...

Tanner• 12 years ago

From my cursory evaluation, the debugging support is actually better than vanilla Lua. The only point of friction I can see if that you have to "compile" something that is normally interpreted.

MattJ1002• 12 years ago

This is great to see! It's important to note that this isn't just yet another "X compiled to Y using Z", but a VM written from scratch natively in Javascript.

The result is a much smaller size, it's more understandable, hackable, extensible - all things that Lua's standard C implementation is great for. It's likely also easier to optimise this way.

I began on a similar project some years back, but as many spare-time projects go, never finished it: http://code.matthewwild.co.uk/ljs

j-b• 12 years ago

Interesting, any useful resources you recommend for those interested in learning how to write a VM in Javascript as a fun side project?

dubcanada• 12 years ago

Don't write it in JS :)

No but seriously, if you want to write a VM in Javascript, I would suggest learning how to write a VM in a language more suited to writing a VM in. Maybe C or C++ then writing one in Javascript.

drivingmenuts2• 12 years ago

It would be nice to see other languages available as real languages, not compiled down to Javascript. I love me some javascript, but it would be nice to work in Python, in the browser.

neovive• 12 years ago

It would be nice to see Lua embedded as an option within browsers, since it's such a small language and already designed to be embedded.

fit2rule10• 12 years ago

Lua is indeed, embeddable anywhere. Its such an elegant little VM, and you can just put it wherever you want. It is some sort of mad invasive engine .. you use it once, and from that point on you pretty much can't see anywhere else you wouldn't just use it, of course .. if you had to, or wanted to, and .. the more you use the Lua VM stack, the more you just want to keep doing things that way. It is neat.

ojii• 12 years ago

There's http://www.skulpt.org/for Python in the browser.

Cederfjard• 12 years ago

You happened to append for to the url. As a convenience:

http://www.skulpt.org

CmonDev4• 12 years ago

That stuff uses JS. It would be nice to see a Python runtime in-browser with no JS involved whatsoever.

CmonDev4• 12 years ago

That would be an actual true Open Web. It's not going to happen.

greyfade• 12 years ago

Personally, I'd like to see a Scheme or ML dialect, but I'm not one to exclude good languages: I'd love to see some way to portably, reliably, and safely extend all browsers to support new language VMs - including languages like Dart, Python, Ruby, Lisp, etc. - without resorting to huge blobs of JavaScript that half-heartedly implement a half-useful language.

Things like ASM.js are interesting, but not really helpful, in my mind, as it just adds another unnecessary layer of overhead just to be able to implement something interesting in a language suited to it. I just wish browser vendors saw this the way I do.

chc3• 12 years ago

What is the difference between a "real language" and "compiled down to JavaScript"? Like, every language is either interpreted or compiles down to something else. I'm not clear on what the real distinction is here. Are ClojureScript, Dart and Scala not real languages since they compile to JavaScript?

drivingmenuts2• 12 years ago

"Real" is probably the wrong term, chosen too quickly. Byte-code compatible is probably a better descriptor.

inm• 12 years ago

A presentation given at the London Lua Group about it's development: https://skillsmatter.com/skillscasts/3820-developing-a-lua-v...

rblstr• 12 years ago

So weird to see this here

scotth2• 12 years ago

Has support for coroutines -- awesome!

k__2• 12 years ago

[citation needed]

scotth2• 12 years ago

The examples don't support deep linking, so here's how you get to the example:

Try It -> Examples -> Coroutines

nnq2• 12 years ago

...I know it's the fashion to write compile-to-js languages and js-VMs for other languages, but I really have to ask: WHY? I mean, Lua is a dynamic language with first class functions just like Javascript is, no big difference here.

I understand clojurescript, parenscript and haskell to js compilers, because these languages are really different from javascript, so they offer you a very different way of working and different tradeoffs (Clojure, CL, Haskell offer you the ability to choose a programming style that is just not possible in Javascript). Maybe even Opal or Amber - rubyan/smalltalkian oop semantics really are very different from Javascript's and you end up using very different design patterns. And I understand the wish to have static typing for large projects/teams, ergo TypeScript or Dart.

But I really don't understant why would anyone go through such pain (by pain I mean not writing the transcompiler/vm, this is the fun part, I know, but debugging it, maintaining it and debugging the code you use it on), to use a language so similar to Javascript, like Lua or Python, instead of using just plain Javascript and making some minor effort to 'use strict', avoid some dark corners and get used to living with a little less syntactic sugar?

stcredzero6• 12 years ago

WHY? I mean, Lua is a dynamic language with first class functions just like Javascript is, no big difference here.

You can use objects as keys in Lua. This makes a lot of code in Lua a pain to port to JavaScript. I have Lua code I would like to port to JavaScript that this applies to.

nnq2• 12 years ago

Got some sample code or a link to it? I really like figuring out ways to express existing code in a different style/pattern/language :)

Excavator• 12 years ago

Map¹ might've been an option, excepting no support in Safari and IE < 11. Although I dunno about the performance hit, if any.

¹ https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

fit2rule10• 12 years ago

Refactor once: the object key. To a function returning the value of the object. Refactor a second time: function all the object things.

Whats not to like?

MattJ1002• 12 years ago

For the people that wrote Moonshine, it was the ability to use the same language across all platforms[1]. They already have a lot of Lua code on other platforms that was unable to run on the web (without using Flash, which also has a Lua VM available for it).

Lua is very portable, I wouldn't choose Javascript to replace it for multi-platform game development. However Javascript has a monopoly on the web. I don't see why this ought to be.

[1]: Source: https://skillsmatter.com/skillscasts/3820-developing-a-lua-v...

fit2rule10• 12 years ago

Because they were already using Lua as a cross-platform killer language, and wanted to just be able to share game-content with a slick, slimy, javascript layer?

fit2rule10• 12 years ago

Another good one - for those of us who love Lua (I Do!) is the MOAIFiddle editor:

http://getmoai.com/forums/moaifiddle-an-online-moai-editor-a...

(Edit: some direct links to already-working examples: http://moaifiddle.com/Q09BJWGMW6 and http://moaifiddle.com/262FBR1ZR8 and http://moaifiddle.com/262FBR1ZR8/2)

This is a full-blown (web-based) development environment for the MOAI Game toolkit, which just happens to be able to deploy to not only Android, iOS, Windows, Linux, OSX hosts .. but also - as demonstrated - to html5+js hosts.

So, if you've ever wanted to check out MOAI but have been put off by the need to build your own host for the OS of your choice, you can just use moaifiddle to get your project done, see the results directly in-browser, and prepare your app before even having to download the MOAI SDK. Sweet!

(More details about the cross-platform game toolkit, MOAI, are available here: http://getmoai.com/)

woogley• 12 years ago

I love Lua too but I've tried to get into Moai several times and I just can't seem to stomach it. Maybe I let Corona spoil me.

The documentation is especially off-putting: http://getmoai.com/docs/

fit2rule10• 12 years ago

I've been working with MOAI for 3 years now, so I guess I'm quite biased - but I find it awesome.

Yes, the Docs - well these are generated docs, courtesy of doxygen. You really need to start at the wiki, and then work your way through all the samples in $MOAI_ROOT/samples/

http://getmoai.com/wiki/index.php?title=Main_Page

And of course the tutorials and other refs from the github:

https://github.com/moai/moai-dev/

MOAI does take some patience - but on the other side of that effort, is a fantastic framework that makes game development easy and fun. There's something just so elegant about it!

speeder3• 12 years ago

Moai is just... terrible.

I work with Lua-based engines on my startup, and right now the "winner" is Gideros.

Corona is also good (But has several issues that made me use Gideros for the current project, but all currently done projects were made with Corona).

Corona is going for HTML5, I hope Gideros can do something like that soon too.

fit2rule10• 12 years ago

MOAI already renders to HTML5. I don't know what you find terrible about it.. but am interested, so feel free to engage me in conversation. FYI, I've been using MOAI for 3 years so I'm not really feeling any negative reactions towards it as a framework - its really done a lot for me as a developer.

herokusaki2• 12 years ago

How does MOAI compare to LÖVE in terms of "batteries", codebase maturity and libraries written by the community ?

fit2rule10• 12 years ago

Maturity? Not as mature. Libraries written by the community - surprisingly there are a lot of little/efficient frameworks for MOAI already, like moaigui, Hanappe, and Flower. These are all user-contributed extensions that make working with MOAI even more joyous...

But yeah, you'll have to suit up for the task of producing a working MOAI host from sources .. this isn't done for you, it is after all free software and there's nobody to buy a license from ..

EastLondonCoder• 12 years ago

I work with moonshine, if you have any questions I would be happy to answer them.

Twisol2• 12 years ago

This would be even more amazing if there was no dependency on `luac` to compile to Lua bytecode. I'm developing a web application with user-scriptable features, and I'd love to use Lua (to provide a better user experience for my non-webdev audience), but the dependency on a server-side compilation step is a problem for my use-cases.

paulcuth2• 12 years ago

There is a Moonshine extension[1] that uses Yueliang[2] to compile offline in the browser, but it's quite slow. I'm hoping to speed it up a bit in the near future, with the futures I'm working on now.

[1] https://github.com/gamesys/moonshine/tree/master/extensions/... [2] http://yueliang.luaforge.net/

fit2rule10• 12 years ago

Use luac locally to compile the bytecode, then include it in your deployment to the server somewhere?

Twisol2• 12 years ago

The app front-end has user-scriptable features - I should have been more specific. My app has no back-end, and it is unacceptable to set up a back-end for the sole purpose of running luac on user scripts.

Moonshine – A lightweight Lua VM for the browser

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