The current crystal binary in nixpkgs complains about not finding pcre
when you try to compile anything with it, so crystal-flake is necessary
to have a working crystal environment under NixOS.
crystal-flake additionally packages crystalline, which is nice since no
one has been able to successfully create a pull request for nixpkgs yet.
Reference: https://github.com/NixOS/nixpkgs/issues/129002
After waiting 41 minutes to produce an output iso of 6.9 GB, the iso
itself failed to boot when trying to start it. Rather than dealing with
this excruciatingly long build process, I'd much rather use nixos-rebuild
build-vm.