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Lua 5.4.0 beta

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Re: Lua 5.4.0 beta

#91

Post by ufo »

i_feel_great wrote: post #89
yanex wrote: post #24

Earlier quoted context omitted.

I suppose, just to close to-be-closed variables declared inside a sleeping coroutine.

Why not let the function in the coroutine exit normally? Maybe I should go read the docs. Killing a coroutine from the outside looks like poor design/bad idea.

Lua 5.4 has a new feature called to-be-closed variables. It is intended to allow for deterministic freeing of resources, even in the face of possible runtime exceptions. (Sort of like RAII in C++).

The canonical example is that you can mark a variable holding a file handle as to-be-closed and then as soon as you exit the variable's scope the file gets automatically closed (including if exit early due to break, return, or error).

But what is supposed to happen if you are inside a coroutine and pause the execution before reaching the end of the scope, and never resume again? If there are any to-be-closed variables their destructors will never run! Or they might only run after the containing coroutine gets garbage collected, which is not a timely solution. To cover this situation, Lua 5.4 introduced a new coroutine.close function that kills a paused coroutine and runs the destructors of any to-be-closed variables inside it, if there were any.

Re: Lua 5.4.0 beta

#92

Post by hugomg »

dottrap wrote: post #88
hugomg wrote: post #59

Earlier quoted context omitted.

It is no surprise that the benchmarks on the LuaJIT website are going to show it ahead of PUC-Lua, is it? In truth the performance comparison is a bit more complicated than that. :) For a pure Lua comparison LuaJIT is typically going to beat Lua by a large margin. For code that can be JIT compiled you might see ~10x performance improvements and for code that doesn't you might still see around a ~2x improvement becaus…

> I wonder if Lua developers have learnt anything from him with respect to performance. It cannot be emphasized enough that PUC-Lua and LuaJIT have different goals. One goal for PUC-Lua is that it must be portable everywhere and be implementable in pure ANSI C (no platform or architecture specific calls). LuaJIT in contrast contains much handwritten assembly for the specific architectures it supports. PUC-Lua also ca…

We chose the Pallene name because it was another one of Saturn's moon names that sounded nice, and is pronounced the same way in English and Portuguese. The Mike Pall thing was just a coincidence although we certainly can't deny his influence, as you have said :)

Re: Lua 5.4.0 beta

#93

Post by uvtc »

yanex wrote: post #69

It seems that quite a lot of people use Lua. I liked the language, it's tiny and well-made. However, I wasn't happy about the tooling support. IDE plugins, documentation generators, lint checkers – all of this seem abandoned. Is there any similar language (embeddable, good C interoperability) with better tooling besides JavaScript?

If you want Lua under the hood, but a more industrial-strength language on top, you might have a look at Haxe. It can compile to Lua (among other languages/platforms).

https://haxe.org/manual/target-lua-getting-started.html

Re: Lua 5.4.0 beta

#94

Post by OskarS »

corysama wrote: post #52
ecmascript wrote: post #14

People that use lua, what do you use it for and why did you pick lua?

I’ve used it in many games. It’s a simple, but powerful language that uses basically two features (functions and hashmaps) to implement everything. Ex: script files are implicitly functions. Global variables are in a hashmap. Semantically it is very much JavaScript without all the surprises. Semi-technical users (artists and designers) can figure it out and go on to make surprisingly powerful features. The binary cod…

Your last line there is really one of the big keys. No other language is as easy to embed and interface with C/C++. The only real exceptions are some varieties of Lisp, but the "easily embeddable" ones tend not to be as mature, performant and robust as Lua.

I'm no particular fan of the language, but they do the "embed and interface with C/C++" better than anything else I've seen.

Re: Lua 5.4.0 beta

#95

Post by [deleted] »

yanex wrote: post #69

It seems that quite a lot of people use Lua. I liked the language, it's tiny and well-made. However, I wasn't happy about the tooling support. IDE plugins, documentation generators, lint checkers – all of this seem abandoned. Is there any similar language (embeddable, good C interoperability) with better tooling besides JavaScript?

[deleted]

Re: Lua 5.4.0 beta

#96

Post by unbendable »

pier25 wrote: post #80
unbendable wrote: post #22

We use lua 5.3 on an embedded Platform for scripting and it has been a roller coaster ride. Not a fun one, unfortunately. You want luasocket? The stable one is not compatible with 5.3. Packages are sometimes outdated (for years no updates) and there is no replacement. The lua point releases have breaking changes. The source code itself is a macro hell which is hard to debug. And the code is not very readable. The doc…

> The thing is lua on embedded has no rival What about something like Nim which compiles to C? https://nim-lang.org/

I just had a short glimpse, but it seems that this is rather "transpiling" to C, right? We needed something that is being interpreted to allow easy updates of scripts.

Comment on all subjects (I will just link it to other commenters): A lot of commenters posted some projects with JS interpreter. But we had to chose something that is stable and is being maintained. The last thing is always hard to argue about because you never know how long maintainers stay commited to the project. But the LUA interpreter is widely used for a lot of (commercial) projects. So there is high chance that it stays for some time. We tried out some other projects, sometimes looking into mailing lists and github issues where we would find open bugs where the interpreter leaks under some circumstances or other problems that you just want to avoid.

LUA seemed a perfect fit and i think still is, but there are still things that didn't work as planned. I really love the concept of the interpreter with the stack. But, again, scheduling is a very complex topic and that is where i found the lua documentation lacking. Especially scheduling between LUA C. I found some projects that solve this issue but then we stumbled upon other issues: Some projects were for 5.1 and didn't work for us. Others used features we didn't have on embedded (pthreads). So we decided to do a very basic scheduling but had to understand more what happens under the hood. And that is where the source code is not easily readable. Don't get me wrong i am convinced that the devs are great at their work, but holy moly you can't use more readable name for you variables? Or the use of macros, is it really neccessary to use it for every conversion?

Re: Lua 5.4.0 beta

#97

Post by unbendable »

jsd1982 wrote: post #79
unbendable wrote: post #22

We use lua 5.3 on an embedded Platform for scripting and it has been a roller coaster ride. Not a fun one, unfortunately. You want luasocket? The stable one is not compatible with 5.3. Packages are sometimes outdated (for years no updates) and there is no replacement. The lua point releases have breaking changes. The source code itself is a macro hell which is hard to debug. And the code is not very readable. The doc…

I'm not sure which embedded platform you're using but give AngelScript [0] a look. I've been using it to extend some C++ code (bsnes emulator) and it's been fantastic. It's so nice to have a C++-like scripting language with natural script-host bindings that I don't have to think hard about creating or spend a lot of time writing marshalling code or worrying about memory layouts. On top of that nice script-host interf…

https://news.ycombinator.com/item?id=21156235

Re: Lua 5.4.0 beta

#98

Post by unbendable »

dividuum wrote: post #31
unbendable wrote: post #22

We use lua 5.3 on an embedded Platform for scripting and it has been a roller coaster ride. Not a fun one, unfortunately. You want luasocket? The stable one is not compatible with 5.3. Packages are sometimes outdated (for years no updates) and there is no replacement. The lua point releases have breaking changes. The source code itself is a macro hell which is hard to debug. And the code is not very readable. The doc…

> The documentation lacks for some topics of you use the c api. I'm surprised to hear this. I'm doing a lot of Lua and I always thought the documentation is very succinct and complete. I really curious when issues you ran into. > The thing is lua on embedded has no rival. but god did it cost me some nerves. You might take a look at https://bellard.org/quickjs/ and https://duktape.org/ . The latter seems oddly familia…

https://news.ycombinator.com/item?id=21156235

Re: Lua 5.4.0 beta

#99

Post by pier25 »

unbendable wrote: post #96
pier25 wrote: post #80

Earlier quoted context omitted.

> The thing is lua on embedded has no rival What about something like Nim which compiles to C? https://nim-lang.org/

I just had a short glimpse, but it seems that this is rather "transpiling" to C, right? We needed something that is being interpreted to allow easy updates of scripts. Comment on all subjects (I will just link it to other commenters): A lot of commenters posted some projects with JS interpreter. But we had to chose something that is stable and is being maintained. The last thing is always hard to argue about because…

> this is rather "transpiling" to C, right?

Yes, my bad.

Re: Lua 5.4.0 beta

#100

Post by exikyut »

jmiskovic wrote: post #29
ecmascript wrote: post #14

People that use lua, what do you use it for and why did you pick lua?

I've built a collection of Android musical instruments [0] and Lua was big win for the project. I was previously familiar with Lua and Love2D framework and I wanted to see how far I can push it. The language is expressive and lightning fast. Very few building blocks that fit together nicely. I dig tables as first class objects, and meta-tables to turn them into complex objects or call delegation mechanism. My favorit…

This is awesome, hilarious and fun. Thanks for posting it!
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