The type for command-line arguments that reads a value of type 'a.

create ~pos ?packages v is the runtime argument pointing to the value v. pos is expected to be __POS__. packages specifies in which opam package the value v is defined. This should be constrained to the correct type of the variable it is pointing to.

The type command-line arguments where the type of the value is abstract.

v k is the k with its type hidden.

Set implements sets over t elements.

call fmt k outputs name () to fmt, where n is k's OCaml name.

serialize ctx ppf k outputs the Cmdliner runes to parse command-line arguments represented by k at runtime.