function pack
    if test (count $argv) -lt 2
        echo "Usage: pack <archive-name> <file-or-dir> [more files...]"
        return 1
    end
    if not command -q tar
        echo "pack: 'tar' is not installed. Install it via your package manager."
        return 1
    end

    set archive $argv[1]
    set targets $argv[2..-1]

    if not string match -q '*.tar.xz' -- $archive
        set archive "$archive.tar.xz"
    end

    tar -cJvf $archive $targets
end