Reduce into unique addresses

addressbook.cabal

@@ -35,6 +35,7 @@ library
                      , text
                      , bytestring-trie
                      , vector
+                     , containers
   hs-source-dirs:      src
   default-language:    Haskell2010
 

default.nix

@@ -1,7 +1,7 @@
 { mkDerivation, attoparsec, base, bytestring, bytestring-trie
-, conduit, conduit-extra, hedgehog, hedgehog-corpus, HUnit, lens
-, mtl, optparse-applicative, stdenv, tasty, tasty-hedgehog
-, tasty-hunit, text, vector
+, conduit, conduit-extra, containers, hedgehog, hedgehog-corpus
+, HUnit, lens, mtl, optparse-applicative, stdenv, tasty
+, tasty-hedgehog, tasty-hunit, text, vector
 }:
 mkDerivation {
   pname = "addressbook";
@@ -11,7 +11,7 @@ mkDerivation {
   isExecutable = true;
   libraryHaskellDepends = [
     attoparsec base bytestring bytestring-trie conduit conduit-extra
-    lens mtl text vector
+    containers lens mtl text vector
   ];
   executableHaskellDepends = [ base optparse-applicative ];
   testHaskellDepends = [

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)