Reproducible, isolated demonstrations

Earlier this week, I put together installation instructions for a syntax support package for Vim.

I have an idea how these things work and I'm fairly confident that -u NONE will get Vim to disregard my years of sensibly crafted configuration, but I wanted to go one step further: from zero to a working plug-in, undoubtedly reproducible on any machine.

I spun up a fleeting shell session in a base Docker image of my distribution of choice, installed the editor, the plug-in, verified its functionality and voilà!

docker run --rm -it archlinux sh
pacman -Sy --noconfirm vim git
cat > work.klg <<EOF
2025-08-10 (8h!)
Getting some #work done.
    08:45 - ?
    -1h #lunch
EOF
# The demonstrably complete instructions: have the plug-in on your runtimepath
git clone https://github.com/73/vim-klog.git
vim -u NONE +'set rtp+=vim-klog' +'syn on' work.klg

Just like that, a fresh Vim installation, augmented with the correct file type detection and corresponding syntax highlighting, right off the master branch of its plug-in's source code: no compilation even needed¹. Wanna give it a spin? Assuming you already have your favourite distribution's image ready, pasting the few commands above gets you up and running in 5 seconds flat.

With the simple docker run command, your container will be pruned as soon as you exit your shell: the above excerpt even contains all the clean-up you need.

I figured I'd try with Neovim, too, to make sure that the exact same instructions (using nvim instead of vim) work just as well. Lo and behold: of course it does.

No more guesswork, no more "well, on my machine [...]"; we have access to as many fully isolated environments as we want: make good use of them!