It is on you to detect that the help flag has been set and then (probably) print get_help_string.
You can modify the help option using the help_option field in the return value of the file.

Register more types converters using the register_type function.
There are already type converters registered for "string", "number" and "boolean".

Finally use parse to parse a string array using a given config.

It can be used to only parse a part of the string array.
To tell it where to start parsing in the array provide the start_index (third param).
To know where it stopped parsing use the second return value.
Both of these indexes are one based including including.

Here is a config i used during development:

localresult=parse(arg, {
options= {
{
field="option", -- results in a boolean, true or false, set or not setlong="option",
short="o",
description="my option",
flag=true,
},
{
field="foo", -- results in an array with 1 or 2 numberslong="foo",
short="f",
min_params=1,
max_params=2,
type="number",
},
{
field="bar", -- results in a single value, a stringshort="b",
single_param=true,
type="string",
},
{
field="baz", -- results in an array with 3 stringslong="baz",
params=3,
type="string",
optional=true,
},
},
positional= {
{
name="yes",
field="yes", -- results in a boolean valuedescription="a bool, yes",
type="boolean", -- the first arg that is not consumed by options must be a boolsingle=true, -- and it must be provideddefault_value=false, -- and if not provided it's not an error, it's just false
},
{
name="files",
field="files",
type="string",
min_amount=0, -- all other positional args
}
},
})

And here's an example for how i use it in general at the moment

localarg_parser=require("arg_parser")
localargs_config= {
-- configure options and positional args here
}
localargsdolocalerrargs, err=arg_parser.parse({...}, args_config)
if (notargs) orargs.helpthenifnotargsthenprint(err)
print()
endprint(arg_parser.get_help_string(args_config))
returnendend

There are sumneko.lua EmmyLua docs at the bottom of the arg_parser.lua file, read those to understand how to configure options.

-- TODO: spend some time making the readme better.