luaenv

Until I can spec this out fully, I’m just going to quote my original blurb:

Even though Lua was intended as an embedded language, its standalone interpreter makes testing modules much easier. However, testing against multiple versions of Lua isn’t exactly straightforward. luarocks, a module manager similar to Ruby Gems, hard-codes the path to Lua not only in config files but the luarocks script itself. Worse, Lua’s module loader assumes Lua is installed in /usr/local on Unix systems. Users can override the search path in the standlone interpreter by setting an environment variable, and within the interpreter one can change package.path and package.cpath. It might be simpler, though, to change those defaults to the directory in which Lua is installed – found once in luaconfig.h – and then compile the interpreter.

Following in the footsteps of rvm and especially rbenv, this Lua Environment Version Manager thing would let developers install multiple versions of Lua in their home directories, set a default, type lua at the command line, and it would Just Work. Likewise installed Lua Rocks would Just Work.

…

A fully functional version would download Lua versions, tweak the default load path, compile Lua, and install it in a version-specific directory. Subcommands would set the default version, list all installed versions, uninstall a version, and so on. luaenv need not support every facility of rbenv though. A user default version overriden by an environment variable would suffice. (Directory-specific configuration would be nice to have, though.)luaenv would also need only a few “shims”, mainly for lua, luac, luarocks, and luarocks-admin, although conceivably a Lua Rock could include an executable script.

Update 2024-11-08

There are at least three projects that maintain multiple Lua versions:

1. https://github.com/cehoffman/luaenv

   A clone of rbenv but altered for Lua.

2. https://github.com/spacekookie/luaenv

   Creates virtual environments similar to rvm or vert, but, and I quote,

   luaenv doesn’t clutter your home directory with more .folders. It uses unix standards where things should be stored

3. https://github.com/DhavalKapil/luaver

   Installs, uninstalls, and switches between versions of Lua, Lua Rocks, and LuaJIT.

Comparing the features of these three:

From this superficial comparison, it looks like luaenv #1 is closest to what I envisioned … but it lacks versions, so it’s not available through Homebrew, my package manager of choice.

So I’m installing luaver through Homebrew and luaenv #1 through git. I’ll tinker with each one and see which I like better.

As for luaenv #2 … I don’t use the fish shell, and I can’t get it to work even if I start a fish shell. So that one’s clearly out. If I get bored maybe I’ll port it to sh/bash/dash. I like that it uses either $HOME/.local/** or an “env” directory to create virtual environments, which may be more appropriate for lightweight Lua than, say, Python.

Update 2024-11-09

I found a fourth one:

4. https://github.com/aconbere/vert

   Creates virtual environments just like Python.

It’s a Lua program installed through LuaRocks. That’s exactly what I was talking about above, although due to a quirk in LuaRocks I can’t get it to not import the LuaRocks I’ve installed in my home directory. So either I stick with luaver and vert exclusively, or I live with possible contamination of virtual environments.

Speaking of, luaenv #1’s support for LuaRocks is old and buggy, so I’m less enamored of it. luaver seems to install multiple copies of the same luarocks distribution, but at least it works. Not that luaver doesn’t have its quirks: you have to specify version numbers exactly, and its technique of rewriting the PATH variable seems a little fragile, but it works. Mostly.