Guix

This is a minimalistic parser of command line options. The main advantage of the library is the ability to concisely define command line options once and then use this definition for parsing and extraction of command line arguments, as well as printing description of command line options (you get --help for free). This way you don't need to repeat yourself. Also, unix-opts doesn't depend on anything and precisely controls the behavior of the parser via Common Lisp restarts.