use format/3 to benefit from efficiency improvements
@@ -460,7 +460,7 @@ portray_clause(Term) :-
portray_clause(Stream, Term) :-
phrase(portray_clause_(Term), Ls),
- maplist(put_char(Stream), Ls).
+ format(Stream, "~s", [Ls]).
portray_clause_(Term) -->
{ term_variables(Term, Vs),
