Make read_term understand the three read options:

	variables(Vars),
	variable_names(VarNames),
	singletons(Singles)

as required per the ISO standard

1 files changed, 28 insertions, 1 deletions

diff --git a/stdlib.pl b/stdlib.pl
index 96132f0..5d2af9f 100644
--- a/stdlib.pl
+++ b/stdlib.pl
@@ -97,6 +97,24 @@ syntax_error(Error) :-
 	throw(error(syntax_error(Error), _)).
 
 % Input and output
+parse_read_option(variables(Vs), options(variables, Vs)).
+parse_read_option(variable_names(VNames), option(variable_names, VNames)).
+parse_read_option(singletons(S), options(singletons, S)).
+
+parse_read_options([], []).
+parse_read_options([Op|Rest], [OpParsed|RestParsed]) :-
+	is_nonvar(Op),
+	parse_read_options(Rest, RestParsed),
+	( parse_read_option(Op, OpParsed)
+	-> true
+	; domain_error(read_option, Op)
+	).
+
+read_term(S, Term, Options) :-
+	is_nonvar(Options),
+	is_list(Options),
+	parse_read_options(Options, ParsedOptions),
+	'$read_term'(S, Term, ParsedOptions).
 
 read_term(Term, Options) :-
 	current_input(S),
@@ -106,6 +124,9 @@ read(Term) :-
 	current_input(S),
 	read_term(S, Term, []).
 
+read(S, Term) :-
+	read_term(S, Term, []).
+
 write_term(Term, Options) :-
 	current_output(S),
 	write_term(S, Term, Options).
@@ -128,6 +149,10 @@ write_canonical(Term) :-
 write_canonical(S, Term) :-
 	write_term(S, Term, [quoted(true), ignore_ops(true)]).
 
+nl :-
+	write_term('
+', []).
+
 % Arithmetic comparisons defined in terms of >=. This is not the most effective way,
 % but it is fine for now.
 
@@ -240,6 +265,8 @@ is_nonvar(T) :- nonvar(T), ! ; instantiation_error.
 
 is_list_or_partial_list(T) :- (list(T) ; partial_list(T)), ! ; type_error(list, T).
 
+is_list(T) :- list(T), ! ; type_error(list, T).
+
 % All solutions
 
 findall(Template, Goal, Instances) :-
@@ -405,4 +432,4 @@ atom_concat(A1, A2, A3) :-
 	atom_codes(A1, Codes1),
 	atom_codes(A2, Codes2).
 atom_concat(A1, A2, A3) :-
-	instantiation_error.
\ No newline at end of file
+	instantiation_error.