diff --git a/src/prolog/lib/non_iso.pl b/src/prolog/lib/non_iso.pl
new file mode 100644
index 00000000..b80d9fac
--- /dev/null
+++ b/src/prolog/lib/non_iso.pl
@@ -0,0 +1,10 @@
+%% for builtins that are not part of the ISO standard.
+%% must be loaded at the REPL with
+
+%% ?- use_module(library(non_iso)).
+
+:- module(non_iso, [forall/2]).
+
+forall(Generate, Test) :-
+    \+ (Generate, \+ Test).
+