val (%:) : string ‑> 'a Arg_type.t ‑> 'a t(name %: typ) specifies a required anonymous argument of type typ.
The name must not be surrounded by whitespace, if it is, an exn will be raised.
If the name is surrounded by a special character pair (<>, {}, [] or (),)
name will remain as-is, otherwise, name will be uppercased.
In the situation where name is only prefixed or only suffixed by one of the
special character pairs, or different pairs are used, (e.g. "<ARG]") an exn will
be raised.
The (possibly transformed) name is mentioned in the generated help for the
command.
sequence anons specifies a sequence of anonymous arguments. An exception
will be raised if anons matches anything other than a fixed number of
anonymous arguments
non_empty_sequence_as_pair anons and non_empty_sequence_as_list anons are like
sequence anons except that an exception will be raised if there is not at least
one anonymous argument given.
t2, t3, and t4 each concatenate multiple anonymous argument
specs into a single one. The purpose of these combinators is to allow
for optional sequences of anonymous arguments. Consider a command with
usage:
main.exe FOO [BAR BAZ]
where the second and third anonymous arguments must either both be there or both not be there. This can be expressed as:
t2 ("FOO" %: foo) (maybe (t2 ("BAR" %: bar) ("BAZ" %: baz)))]
Sequences of 5 or more anonymous arguments can be built up using nested tuples:
maybe (t3 a b (t3 c d e))