add term variables

src/prolog/lib/numbervars.pl

@@ -1,29 +0,0 @@
-:- module(numbervars, [numbervars/2, numbervars/3]).
-
-numbervars(Term, NewTerm) :- duplicate_term(Term, NewTerm), numbervars(Term, NewTerm, 0, _).
-
-numbervars(Term, NewTerm, N) :-
-    ( integer(N), N >= 0 -> duplicate_term(Term, NewTerm), numbervars(Term, NewTerm, N, _)
-    ; integer(N) -> throw(error(domain_error(not_less_than_zero, N), numbervars/3))
-    ; throw(error(type_error(integer, N), numbervars/3))
-    ).
-
-numbervars(Term, NewTerm, N1, N2) :-
-    var(Term), !, NewTerm = '$VAR'(N1), N2 is N1 + 1.
-numbervars(Term, NewTerm, N1, N2) :- compound(Term), !,
-    Term =.. [Name | Args],
-    NewTerm =.. [Name | NewArgs],
-    fold_numbervars(Args, NewArgs, N1, N2).
-numbervars(_, _, N, N).
-
-marked_already(Term, NewTerm) :-
-    var(Term), nonvar(NewTerm), NewTerm = '$VAR'(_).
-marked_already(Term, NewTerm) :-
-    atomic(Term).
-
-fold_numbervars([HeadTerm | Terms], [NewHeadTerm | NewTerms], N1, Nn) :-
-    ( marked_already(HeadTerm, NewHeadTerm) -> N1 = N2
-    ; numbervars(HeadTerm, NewHeadTerm, N1, N2)
-    ),
-    fold_numbervars(Terms, NewTerms, N2, Nn).
-fold_numbervars([], [], N, N).

src/prolog/lib/terms.pl

@@ -0,0 +1,19 @@
+:- module(terms, [term_variables/2, numbervars/2, numbervars/3]).
+
+term_variables(Term, Vars) :- '$term_variables'(Term, Vars).
+
+numbervars(Term, N) :-
+    integer(N),
+    term_variables(Term, Vars),
+    numberlist(Vars, N, N1).
+    
+numbervars(Term, N0, N) :-
+    integer(N0),
+    integer(N),
+    term_variables(Term, Vars),
+    numberlist(Vars, N0, N).
+
+numberlist([], N,N).
+numberlist(['$VAR'(N0)|Vars], N0,N) :-
+   N1 is N0+1,
+   numberlist(Vars, N1,N).