remove vestigial prolog/ directory (#444)

src/machine/attributed_variables.pl

@@ -0,0 +1,52 @@
+:- module('$atts', []).
+
+driver(Vars, Values) :-
+    iterate(Vars, Values, ListOfListsOfGoalLists),
+    !,
+    call_goals(ListOfListsOfGoalLists),
+    '$return_from_verify_attr'.
+
+iterate([Var|VarBindings], [Value|ValueBindings], [ListOfGoalLists | ListsCubed]) :-
+    '$get_attr_list'(Var, Ls),
+    call_verify_attributes(Ls, Var, Value, ListOfGoalLists),
+    '$redo_attr_var_binding'(Var, Value),
+    iterate(VarBindings, ValueBindings, ListsCubed).
+iterate([], [], []).
+
+gather_modules(Attrs, []) :- var(Attrs), !.
+gather_modules([Attr|Attrs], [Module|Modules]) :-
+    '$module_of'(Module, Attr),  % write the owning module of Attr to Module.
+    gather_modules(Attrs, Modules).
+
+call_verify_attributes(Attrs, _, _, []) :-
+    var(Attrs), !.
+call_verify_attributes([], _, _, []).
+call_verify_attributes([Attr|Attrs], Var, Value, ListOfGoalLists) :-
+    gather_modules([Attr|Attrs], Modules0),
+    sort(Modules0, Modules),
+    verify_attrs(Modules, Var, Value, ListOfGoalLists).
+
+verify_attrs([Module|Modules], Var, Value, [Goals|ListOfGoalLists]) :-
+    catch(Module:verify_attributes(Var, Value, Goals),
+          error(evaluation_error((Module:verify_attributes)/3), verify_attributes/3),
+          Goals = []),
+    verify_attrs(Modules, Var, Value, ListOfGoalLists).
+verify_attrs([], _, _, []).
+
+call_goals([ListOfGoalLists | ListsCubed]) :-
+    call_goals_0(ListOfGoalLists),
+    call_goals(ListsCubed).
+call_goals([]).
+
+call_goals_0([GoalList | GoalLists]) :-
+    (  var(GoalList), throw(error(instantiation_error, call_goals_0/1))
+    ;  true
+    ),
+    call_goals_1(GoalList),
+    call_goals_0(GoalLists).
+call_goals_0([]).
+
+call_goals_1([Goal | Goals]) :-
+    call(Goal),
+    call_goals_1(Goals).
+call_goals_1([]).