getopt-generics-0.11: docs/SimpleRecord.shell-protocol
$ program --port 8080 --config some/path
Options {port = 8080, daemonize = False, config = Just "some/path"}
$ program --port 8080 --daemonize
Options {port = 8080, daemonize = True, config = Nothing}
$ program --port foo
cannot parse as INTEGER: foo
# exit-code 1
$ program
missing option: --port=INTEGER
# exit-code 1
$ program --help
program [OPTIONS]
--port=INTEGER
--daemonize
--config=STRING (optional)
-h --help show help and exit