Reduce into unique addresses

src/Control/Addressbook/Streaming.hs

@@ -9,11 +9,15 @@ import qualified Data.Conduit.Text as CT
 
 import Data.Email
 import Data.Email.Header
-       (Header)
+       (Header(..))
 
 import System.IO
        (stdin)
 
+import qualified Data.Foldable as F
+
+import qualified Data.Set as S
+
 combine :: (MonadUnliftIO m, MonadResource m, MonadThrow m, MonadIO m) => ConduitM FilePath Header m ()
 combine = await >>= \case
   Nothing -> pure ()
@@ -21,4 +25,17 @@ combine = await >>= \case
 
 run :: IO ()
 run = do
-  runResourceT $ runConduit (CB.sourceHandle stdin .| CT.decode CT.utf8 .| CT.lines .| C.map T.unpack .| combine .| C.mapM_ (liftIO . print))
+  x <- runResourceT $ runConduit stream
+  F.for_ x print
+  where
+    separate = \case
+      From x -> [x]
+      To xs -> F.toList xs
+    stream =
+      CB.sourceHandle stdin
+        .| CT.decode CT.utf8
+        .| CT.lines
+        .| C.map T.unpack
+        .| combine
+        .| C.concatMap separate
+        .| C.foldMap (S.singleton)