remove $reify_switch

src/prolog/lib/reif.pl

@@ -4,18 +4,13 @@
 
 :- use_module(library(dif)).
 
-/* in essence, '$reify_switch'(T, Then_0, Else_0) is semantically this,
-    (  T == true -> call(Then_0)
+if_(If_1, Then_0, Else_0) :-
+    call(If_1, T),
+    (  T == true  -> call(Then_0)
     ;  T == false -> call(Else_0)
     ;  nonvar(T) -> throw(error(type_error(boolean, T), _))
     ;  throw(error(instantiation_error, _))
     ).
-    but it does not create choice points.
-*/
-
-if_(If_1, Then_0, Else_0) :-
-    call(If_1, T),
-    '$call_with_default_policy'('$reify_switch'(T, Then_0, Else_0)).
 
 =(X, Y, T) :-
     (  X == Y -> T = true