The real reason everyone settled on Lua 5.1 is because that's the version LuaJIT is compatible with, and most people are unwilling to give up the performance gains.

And Luau.

5.1 (by way of LuaJIT) gets a lot of use, but to suggests no one uses the modern versions is just not true. Lua being an embedded language just takes the pressure away to upgrade. It's a feature, not a bug.

> everything seems to have settled on 5.1

Not exactly. LuaJIT has backported various hot features from 5.2 and 5.3 as long as they're unlikely to break 5.1 code.

I'm pretty sure that's only OpenResty's distribution of LuaJIT.

I think the real LuaJIT is strictly 5.1

Not true, see "Extensions from Lua 5.2" here: https://luajit.org/extensions.html

No, real LuaJIT has some features from 5.2 and 5.3

https://luajit.org/extensions.html

True. But

1. The luajit documentation basically just had a list of features. AFAIK there isn't any documentation that combines the 5.1 reference with luajit extensions (including things that were backported)

2. In some cases, for example Neovim, luajit extensions aren't guaranteed to be available. It just says there will be a lua runtime compatible with 5.1. Which means a truly portable neovim plugin can't use those extensions

3. There are features from later lua versions I would like to have (in particular <const> and <close>) that will probably never get backported.

4. Some features require luajit to be built with special flags