src/Pure/ML-Systems/install_pp_polyml-experimental.ML

+(*  Title:      Pure/ML-Systems/install_pp_polyml-experimental.ML
+
+Extra toplevel pretty-printing for Poly/ML; experimental version for
+Poly/ML 5.3.
+*)
+
+local
+
+fun pretty_future depth (pretty: 'a * int -> pretty) (x: 'a future) =
+  (case Future.peek x of
+    NONE => PrettyString "<future>"
+  | SOME (Exn.Exn _) => PrettyString "<failed>"
+  | SOME (Exn.Result y) => pretty (y, depth));
+
+fun pretty_lazy depth (pretty: 'a * int -> pretty) (x: 'a lazy) =
+  (case Lazy.peek x of
+    NONE => PrettyString "<lazy>"
+  | SOME (Exn.Exn _) => PrettyString "<failed>"
+  | SOME (Exn.Result y) => pretty (y, depth));
+
+in
+
+val _ = addPrettyPrinter pretty_future;
+val _ = addPrettyPrinter pretty_lazy;
+
+end;
+