GUESS ¯\_ :( _/¯ what version of unify they are trying to use? ¯(°_…

…o)/¯ trueagi-io/hyperon-experimental#805

prolog/metta_lang/metta_eval.pl

@@ -1163,19 +1163,23 @@
 % =================================================================
 % =================================================================
 % =================================================================
-sub_part(Container,Item):- is_space(Container),!,metta_atom(Container,Item).
-sub_part(Container,Item):-  is_list(Container),!,member(Item,Container).
+metta_container_sub_part(Container,Item):- is_space(Container),!,metta_atom(Container,Item).
+metta_container_sub_part(Container,Item):-  is_list(Container),!,member(Item,Container).
 
+% GUESS `¯\\_ :( _/¯` what version of unify they are trying to use? ¯(°_o)/¯
+
+% 1) If Arg1 is a space, then we redirect to a 'match' operation.
 eval_20(Eq,RetType,Depth,Self,['unify',Arg1,Arg2|Args],Res):- is_space(Arg1), !,
   eval_args(Eq,RetType,Depth,Self,['match',Arg1,Arg2|Args],Res).
-% require someone declared this a container of some sort?
+% 2) If Arg1 and Arg2 are nonvars and Arg1 is declared a 'Container', then use 'container-unify'
 eval_20(Eq,RetType,Depth,Self,['unify',Arg1,Arg2|Args],Res):- nonvar(Arg1), nonvar(Arg2), get_type(Depth,Self,Arg1,'Container'),
   eval_args(Eq,RetType,Depth,Self,['container-unify',Arg1,Arg2|Args],Res).
+% 3) Otherwise, default to using 'if-unify' for the unify operation.
 eval_20(Eq,RetType,Depth,Self,['unify',Arg1,Arg2|Args],Res):- !,
   eval_args(Eq,RetType,Depth,Self,['if-unify',Arg1,Arg2|Args],Res).
 
 eval_20(Eq,RetType,Depth,Self,['container-unify',Arg1,Arg2,Then|ElseL],Res):-
-   ((sub_part(Arg1,Part),eval_args_true(Eq,'Bool',Depth,Self,['==',Part,Arg2]))
+   ((metta_container_sub_part(Arg1,Part),eval_args_true(Eq,'Bool',Depth,Self,['==',Part,Arg2]))
     *-> eval_args(Eq,RetType,Depth,Self,Then,Res)
     ; (ElseL=[Else],eval_args(Eq,RetType,Depth,Self,Else,Res))).