fixed occurs check in match

Author: Roy Ward

prolog/metta_lang/metta_compiler_lib.pl

@@ -333,7 +333,7 @@
 
 transpiler_predicate_store(builtin, match, [3], '@doc', '@doc', [x(doeval,eager,[]), x(noeval,eager,[]), x(doeval,lazy,[])], x(doeval,eager,[])).
 'mc__1_3_match'(Space,P,P1,Ret) :- is_list(P),P=[Comma|Patterns],Comma==',',!,(maplist(match_aux(Space),Patterns) -> as_p1_exec(P1,Ret) ; fail).
-'mc__1_3_match'(Space,Pattern,P1,Ret) :- match_pattern(Space, Atom),Atom=Pattern,as_p1_exec(P1,Ret).
+'mc__1_3_match'(Space,Pattern,P1,Ret) :- match_pattern(Space, Atom),unify_with_occurs_check(Atom,Pattern),as_p1_exec(P1,Ret).
 %'mc__1_3_match'(Space,Pattern,P1,Ret) :- match_pattern(Space, Atom),format("match1 ~w: ~w:\n",[Pattern,Atom]),Atom=Pattern,as_p1_exec(P1,Ret),format("match2 ~w:\n",[Ret]),trace.
 %transpiler_predicate_store(builtin, match, [3], '@doc', '@doc', [x(doeval,eager,[]), x(doeval,lazy,[]), x(doeval,lazy,[])], x(doeval,eager,[])).
 %'mc__1_3_match'(Space,Pattern,P1,Ret) :- match_pattern(Space, Atom),as_p1_exec(Pattern,Atom),as_p1_exec(P1,Ret).