function pack
    if test (count $argv) -lt 2
        echo "Usage: pack <archive-name> <file-or-dir> [more files...]"
        return 1
    end

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

    # Ensure .tar.xz extension
    if not string match -r '\.tar\.xz$' -- $archive
        set archive "$archive.tar.xz"
    end

    tar -cJvf $archive $targets
end