1:- module(swi_options,
    2          [ select_options/4    % +Options,+RestOptions0,-RestOptions,+Defaults
    3          ]).    4:- autoload(library(option), [select_option/4]).

 select_options(+Options, +RestOptions0, -RestOptions, +Defaults) is det

Applies multiple select_option/4 predicate calls to a list of Options. Applies the list of Options using a list of Defaults. Argument terms from Options unify with RestOptions0.

Defaults are unbound if not present. The implementation selects an option's Default from the given list of Defaults using select_option/4. Option terms must have one variable. This is because select_option/4's fourth argument is a single argument. It never unifies with multiple variables even though it succeeds, e.g. select_option(a(A, B), [], Rest, 1) unifies A with 1, leaving B unbound.

There is a naming issue. What to call the incoming list of Option arguments and the Options argument with which the Option terms unify? One possibility: name the Options argument RestOptions0 since they represent the initial set of RestOptions from which Options select. This clashes with select_option/4's naming convention since Options is the argument name for RestOptions0's role in the option-selection process. Nevertheless, this version follows this renamed argument convention.

   32select_options(Options, RestOptions0, RestOptions, Defaults) :-
   33    select_options(Options, RestOptions0, RestOptions, Defaults, _).
   34
   35select_options([], RestOptions, RestOptions, Defaults, Defaults).
   36select_options([Option|Options], RestOptions0, RestOptions, Defaults0, Defaults) :-
   37    copy_term(Option, Option1),
   38    term_variables(Option1, [Default]),
   39    select_option(Option1, Defaults0, Defaults1, _),
   40    select_option(Option, RestOptions0, RestOptions1, Default),
   41    select_options(Options, RestOptions1, RestOptions, Defaults1, Defaults)