1 files changed, 5 insertions, 0 deletions
diff --git a/compiler/utils/Maybes.lhs b/compiler/utils/Maybes.lhs
index 8a612fbb60..859908e266 100644
--- a/compiler/utils/Maybes.lhs
+++ b/compiler/utils/Maybes.lhs
@@ -14,6 +14,7 @@ module Maybes (
         mapCatMaybes,
         allMaybes,
         firstJust, firstJusts,
+        whenIsJust,
         expectJust,
         maybeToBool,
 
@@ -68,6 +69,10 @@ mapCatMaybes _ [] = []
 mapCatMaybes f (x:xs) = case f x of
                         Just y  -> y : mapCatMaybes f xs
                         Nothing -> mapCatMaybes f xs
+
+whenIsJust :: Monad m => Maybe a -> (a -> m ()) -> m ()
+whenIsJust (Just x) f = f x
+whenIsJust Nothing  _ = return ()
 \end{code}
 
 \begin{code}