1 files changed, 10 insertions, 0 deletions
diff --git a/common.sml b/common.sml
index e648203..d039471 100644
--- a/common.sml
+++ b/common.sml
@@ -179,6 +179,16 @@ type ('t1, 't2, 'a, 'b, 'c) a2printer =
     (bool * ((string -> unit) * 'a)) * 'b -> 't1 -> 't2 ->
         ((bool * ((string -> unit) * 'a)) * 'b -> 'c) -> 'c
 
+val Popt = fn z =>
+let
+  fun f (out, p, v) =
+    case v of
+      NONE => Printf out `"none" %
+    | SOME v => Printf out p v %
+in
+  bind A2 f
+end z
+
 fun die code g =
 let
   fun finish (true, _) = raise Unreachable