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Lua's biggest thing is that it's pretty easy to embed inside a C/C++ application safely, for relative definitions of "safe" spanning "preventing the Lua code fr

Lua's biggest thing is that it's pretty easy to embed inside a C/C++ application safely, for relative definitions of "safe" spanning "preventing the Lua code from segfaulting your application" to "preventing the Lua code from doing anything you don't explicitly give it the ability to do". It's why you see it used as so many game's plugin architecture and why it was selected for NeoVim. So there is a very large ecosystem of Lua code that just lives in Lua 5.1 and doesn't really push forward at all. I haven't checked in on the situation for some time, but most people who write Lua are writing Lua for something like NeoVim or WoW or some other plugin for a larger project. Those projects have no interest in dealing with the slow reference VM for Lua >=5.2 at this time. Lua 5.2, 5.3, and 5.4 are more analogous to Python 2 to Python 3's level of change, rather than Python 3.9 to Python 3.10. These more recent versions of Lua 5.x are somewhat incompatible with each other, rather than just adding new language features. Most products settle on Lua 5.1 because that is what luajit, a very fast just in time compiling implementation of the Lua VM supports. Plans to further support to new versions for luajit are...well they exist.

pansa2 5y ago
> WoW [...] have no interest in dealing with the slow reference VM Does WoW use LuaJIT? I thought it used the reference Lua 5.1 VM, simply because that was the newest version when it was first released. > Plans to further support to new versions for luajit are...well they exist. I’m not sure it’ll ever happen. AFAICT LuaJIT is so complex that only its author, Mike Pall, understands it well enough to make major changes. He has expressed his dislike for several of the changes in Lua >= 5.2.
- krinchan 5y ago
  > Does WoW use LuaJIT? I thought it used the reference Lua 5.1 VM, simply because that was the newest version when it was first released. I didn’t mean to imply WoW was using luajit, apologies. I was under the impression that over the years they have patched and fussed with code of the reference VM to resolve some performance pain points in the vanilla UI lua. Unfortunately, I can’t find the source for that. Regardless, I’ve always assumed that they had little interest in both rewriting their vanilla UI to newer versions AND starting over from square one trying to resolve any performance hiccups they hit.

pansa2 5y ago

> WoW [...] have no interest in dealing with the slow reference VM Does WoW use LuaJIT? I thought it used the reference Lua 5.1 VM, simply because that was the newest version when it was first released. > Plans to further support to new versions for luajit are...well they exist. I’m not sure it’ll ever happen. AFAICT LuaJIT is so complex that only its author, Mike Pall, understands it well enough to make major changes. He has expressed his dislike for several of the changes in Lua >= 5.2.

krinchan 5y ago
> Does WoW use LuaJIT? I thought it used the reference Lua 5.1 VM, simply because that was the newest version when it was first released. I didn’t mean to imply WoW was using luajit, apologies. I was under the impression that over the years they have patched and fussed with code of the reference VM to resolve some performance pain points in the vanilla UI lua. Unfortunately, I can’t find the source for that. Regardless, I’ve always assumed that they had little interest in both rewriting their vanilla UI to newer versions AND starting over from square one trying to resolve any performance hiccups they hit.