Add flakes

Co-authored-by: Mats Rauhala <mats.rauhala@iki.fi>
Reviewed-on: #2
Co-authored-by: Mats Rauhala <masse@rauhala.info>
Co-committed-by: Mats Rauhala <masse@rauhala.info>

addressbook.cabal

@@ -16,49 +16,61 @@ maintainer:          mats.rauhala@iki.fi
 -- category:
 extra-source-files:  CHANGELOG.md
 
+common deps
+  build-depends:       base >=4.13.0.0 && <4.15
+
 library
+  import:              deps
   exposed-modules:     MyLib
+                     , Data.Trie
                      , Data.Email.Header
                      , Data.Email
                      , Control.Addressbook.Streaming
+                     , Control.Addressbook.Query
   -- other-modules:
   -- other-extensions:
   default-extensions:  OverloadedStrings
                        LambdaCase
-  build-depends:       base ^>=4.13.0.0
+  build-depends:       attoparsec
-                     , attoparsec
                      , mtl
                      , conduit
                      , conduit-extra
                      , bytestring
                      , lens
                      , text
-                     , bytestring-trie
                      , vector
                      , containers
+                     , filepath
+                     , parallel
+                     , unix
   hs-source-dirs:      src
   default-language:    Haskell2010
+  ghc-options:         -Wall
 
 executable addressbook
+  import:              deps
   main-is:             Main.hs
   -- other-modules:
   -- other-extensions:
-  build-depends:       base ^>=4.13.0.0, addressbook
+  build-depends:       addressbook
                      , optparse-applicative
+                     , text
   hs-source-dirs:      app
   default-language:    Haskell2010
+  ghc-options:         -Wall -threaded -eventlog
 
 test-suite addressbook-test
+  import:              deps
   default-language:    Haskell2010
   default-extensions:  OverloadedStrings
                        LambdaCase
   other-modules:       Test.Data.Email.Header
                      , Test.Data.Email
+                     , Test.Data.Trie
   type:                exitcode-stdio-1.0
   hs-source-dirs:      test
   main-is:             MyLibTest.hs
-  build-depends:       base ^>=4.13.0.0
+  build-depends:       addressbook
-                     , addressbook
                      , tasty
                      , tasty-hedgehog
                      , tasty-hunit
@@ -70,3 +82,27 @@ test-suite addressbook-test
                      , vector
                      , conduit
                      , conduit-extra
+                     , containers
+  ghc-options:         -Wall
+
+
+-- I know there's a benchmark type, but haskellPackages.shellFor doesn't seem
+-- to support it and I don't have the time to figure it out
+executable addressbook-bench
+  import:              deps
+  default-language:    Haskell2010
+  default-extensions:  OverloadedStrings
+                       LambdaCase
+  -- other-modules:       Test.Data.Email.Header
+  --                    , Test.Data.Email
+  --                    , Test.Data.Trie
+  hs-source-dirs:      bench
+  main-is:             Bench.hs
+  build-depends:       addressbook
+                     , criterion
+                     , hedgehog-corpus
+                     , bytestring
+                     , containers
+  ghc-options:         -Wall
+
+

app/Main.hs

@@ -3,18 +3,28 @@ module Main where
 
 import Options.Applicative
 
+import Data.Text
+       (Text)
+import qualified Data.Text as T
+
+import qualified Control.Addressbook.Query as Query
 import qualified Control.Addressbook.Streaming as Streaming
 
 data CmdLine
   = Stream
+  | Query Text
   deriving Show
 
 cmdline :: Parser CmdLine
-cmdline = subparser (command "stream" (info (pure Stream) (progDesc "Record a stream of filenames")))
+cmdline = subparser
+  (  command "stream" (info (pure Stream) (progDesc "Record a stream of filenames"))
+  <> command "query" (info (Query . T.pack <$> argument str (metavar "QUERY")) (progDesc "Query email addresses"))
+  )
 
 handler :: CmdLine -> IO ()
 handler = \case
   Stream -> Streaming.run
+  Query q -> Query.query q
 
 main :: IO ()
 main = execParser opts >>= handler

bench/Bench.hs

@@ -0,0 +1,54 @@
+module Main where
+
+import Criterion.Main (defaultMain)
+import Data.ByteString (ByteString)
+import Hedgehog.Corpus (muppets, simpsons, vegetables, viruses)
+import Criterion
+import qualified Data.Map.Strict as M
+import qualified Data.ByteString.Char8 as B
+import qualified Data.Trie as Trie
+
+setupEnv :: IO ([(ByteString, ())], [(ByteString, ())])
+setupEnv = pure (small, big)
+  where
+    small =
+      [ (firstname <> "." <> surname <> "@" <> domain <> "." <> tld, ())
+      | firstname <- simpsons
+      , surname <- muppets
+      , domain <- vegetables
+      , tld <- ["com", "fi", "co.uk", "info", "org"]
+      ]
+    big =
+      [ (firstname <> "." <> surname <> "@" <> domain1 <> "." <> domain2 <> "." <> tld, ())
+      | firstname <- simpsons
+      , surname <- muppets
+      , domain1 <- vegetables
+      , domain2 <- viruses
+      , tld <- ["com", "fi", "co.uk", "info", "org"]
+      ]
+
+main :: IO ()
+main = defaultMain
+  [ env setupEnv $ \ ~(small,big) -> bgroup "main"
+    [ bgroup "small"
+      [ bgroup "Data.Map"
+        [ bench "length . toList . fromList" $ whnf (length . M.toList . M.fromList) small
+        , bench "length . filter (\"homer\" `isPrefixOf`) . keys . fromList" $ whnf (length . M.keys . M.filterWithKey (\k _ -> "homer" `B.isPrefixOf` k) . M.fromList) small
+        ]
+      , bgroup "Data.Trie"
+        [ bench "length . toList . fromList" $ whnf (length . Trie.toList . Trie.fromList) small
+        , bench "length . keys . submap \"homer\" . fromList" $ whnf (length . Trie.keys . Trie.submap "homer" .  Trie.fromList) small
+        ]
+      ]
+    , bgroup "big"
+      [ bgroup "Data.Map"
+        [ bench "length . toList . fromList" $ whnf (length . M.toList . M.fromList) big
+        , bench "length . filter (\"homer\" `isPrefixOf`) . keys . fromList" $ whnf (length . M.keys . M.filterWithKey (\k _ -> "homer" `B.isPrefixOf` k) . M.fromList) big
+        ]
+      , bgroup "Data.Trie"
+        [ bench "length . toList . fromList" $ whnf (length . Trie.toList . Trie.fromList) big
+        , bench "length . keys . submap \"homer\" . fromList" $ whnf (length . Trie.keys . Trie.submap "homer" .  Trie.fromList) big
+        ]
+      ]
+    ]
+  ]

default.nix

@@ -1,7 +1,7 @@
-{ mkDerivation, attoparsec, base, bytestring, bytestring-trie
+{ mkDerivation, attoparsec, base, bytestring, conduit
-, conduit, conduit-extra, containers, hedgehog, hedgehog-corpus
+, conduit-extra, containers, criterion, filepath, hedgehog
-, HUnit, lens, mtl, optparse-applicative, stdenv, tasty
+, hedgehog-corpus, HUnit, lens, lib, mtl, optparse-applicative
-, tasty-hedgehog, tasty-hunit, text, vector
+, parallel, tasty, tasty-hedgehog, tasty-hunit, text, unix, vector
 }:
 mkDerivation {
   pname = "addressbook";
@@ -10,13 +10,16 @@ mkDerivation {
   isLibrary = true;
   isExecutable = true;
   libraryHaskellDepends = [
-    attoparsec base bytestring bytestring-trie conduit conduit-extra
+    attoparsec base bytestring conduit conduit-extra containers
-    containers lens mtl text vector
+    filepath lens mtl parallel text unix vector
+  ];
+  executableHaskellDepends = [
+    base bytestring containers criterion hedgehog-corpus
+    optparse-applicative text
   ];
-  executableHaskellDepends = [ base optparse-applicative ];
   testHaskellDepends = [
-    base bytestring conduit conduit-extra hedgehog hedgehog-corpus
+    base bytestring conduit conduit-extra containers hedgehog
-    HUnit tasty tasty-hedgehog tasty-hunit text vector
+    hedgehog-corpus HUnit tasty tasty-hedgehog tasty-hunit text vector
   ];
-  license = stdenv.lib.licenses.bsd3;
+  license = lib.licenses.bsd3;
 }

easy-hls-nix.json

@@ -0,0 +1,11 @@
+{
+  "url": "https://github.com/ssbothwell/easy-hls-nix",
+  "rev": "393ccab35104d5d49e0ff9eadf7b8654e87abffd",
+  "date": "2021-09-16T11:13:40-07:00",
+  "path": "/nix/store/dsfqcsiahsp9rkip4fsqzz32x0swa3d4-easy-hls-nix",
+  "sha256": "0q1qxlkzjqx2hvf9k2cp5a98vlvsj13lap6hm7gl1kkqp88ai1dw",
+  "fetchLFS": false,
+  "fetchSubmodules": false,
+  "deepClone": false,
+  "leaveDotGit": false
+}

easy-hsl-nix.json

@@ -0,0 +1,10 @@
+{
+  "url": "https://github.com/jkachmar/easy-hls-nix",
+  "rev": "291cf77f512a7121bb6801cde35ee1e8b7287f91",
+  "date": "2021-04-13T16:12:58-04:00",
+  "path": "/nix/store/wlmckg348q32ylfpg5dv3d5x88nkbi59-easy-hls-nix",
+  "sha256": "1bvbcp9zwmh53sm16ycp8phhc6vzc72a71sf0bvyjgfbn6zp68bc",
+  "fetchSubmodules": false,
+  "deepClone": false,
+  "leaveDotGit": false
+}

flake.lock

@@ -0,0 +1,62 @@
+{
+  "nodes": {
+    "easy-hls": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1637250802,
+        "narHash": "sha256-/crlHEVB148PGQLZCsHOR9L5qgvCAfRSocIoKgmMAhA=",
+        "owner": "jkachmar",
+        "repo": "easy-hls-nix",
+        "rev": "7c123399ef8a67dc0e505d9cf7f2c7f64f1cd847",
+        "type": "github"
+      },
+      "original": {
+        "owner": "jkachmar",
+        "repo": "easy-hls-nix",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1637014545,
+        "narHash": "sha256-26IZAc5yzlD9FlDT54io1oqG/bBoyka+FJk5guaX4x4=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "bba5dcc8e0b20ab664967ad83d24d64cb64ec4f4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1637312849,
+        "narHash": "sha256-OhVZopkyryEfLyPwcXk2IQsdi80lj6TY1YFoMNZ4hCQ=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "e4806bb4416f88c20f8be0b8ef9b5b09ff9022a6",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "easy-hls": "easy-hls",
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,53 @@
+{
+  description = "addressbook";
+
+  inputs = {
+    easy-hls = {
+      url = "github:jkachmar/easy-hls-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    flake-utils = {
+      url = "github:numtide/flake-utils";
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, easy-hls }:
+    { overlay = final: prev: {
+        haskellPackages = prev.haskellPackages.override ( old: {
+          overrides = final.lib.composeExtensions (old.overrides or (_: _: {})) (f: p: {
+            addressbook = f.callPackage ./. {};
+          });
+        });
+      };
+    }
+    //
+    flake-utils.lib.eachSystem ["x86_64-linux" "x86_64-darwin"] ( system:
+      let
+        pkgs = import nixpkgs { inherit system; overlays = [ self.overlay ]; };
+        hp = pkgs.haskellPackages;
+        hls = (easy-hls.withGhcs [ hp.ghc ]).${system};
+      in
+      rec {
+
+        packages = { inherit (hp) addressbook; };
+
+        defaultPackage = packages.addressbook;
+        apps.addressbook = {
+          type = "app";
+          program = "${hp.addressbook}/bin/addressbook";
+        };
+        devShell = hp.shellFor {
+          packages = h: [h.addressbook];
+          withHoogle = true;
+          buildInputs = with pkgs; [
+            entr
+            cabal-install
+            hp.hlint
+            stylish-haskell
+            ghcid
+            hls
+          ];
+        };
+      }
+    );
+}

shell.nix

@@ -1,15 +1,24 @@
 with (import <nixpkgs> {});
 
-let addressbook = haskellPackages.callPackage ./. {};
+let
+  hp = haskellPackages.extend (self: super: {
+    addressbook = self.callPackage ./. {};
+  });
+  easy-hls = callPackage easy-hls-src { ghcVersions = [ hp.ghc.version ]; };
+  easy-hls-src = fetchFromGitHub {
+    owner = "ssbothwell";
+    repo = "easy-hls-nix";
+    inherit (builtins.fromJSON (builtins.readFile ./easy-hls-nix.json)) rev sha256;
+  };
 
 in
 
-mkShell {
+hp.shellFor {
-  name = "addressbook-shell";
+  packages = h: [h.addressbook];
   buildInputs = [
     ghcid
+    easy-hls
     stylish-haskell
     haskellPackages.cabal-install
-    (haskellPackages.ghcWithHoogle (_: addressbook.buildInputs ++ addressbook.propagatedBuildInputs))
   ];
 }

src/Control/Addressbook/Query.hs

@@ -0,0 +1,42 @@
+{-# LANGUAGE TypeApplications #-}
+module Control.Addressbook.Query where
+
+import Data.Text
+       (Text)
+import qualified Data.Text as T
+
+import Conduit
+import qualified Data.Conduit.Binary as CB
+import qualified Data.Conduit.Combinators as C
+import qualified Data.Conduit.Text as CT
+
+
+import System.IO
+       (stdout)
+
+import Data.Maybe
+       (fromMaybe)
+import System.Environment
+       (lookupEnv)
+import System.FilePath
+       ((</>))
+
+import Control.Exception
+       (catch)
+
+-- XXX: The current Data.Trie implementation is much slower than Data.Set
+query :: Text -> IO ()
+query prefix = do
+  datDir <- fromMaybe "./" <$> lookupEnv "HOME"
+  catch @IOError (runResourceT $ runConduit $ filterAddresses datDir) $ \e -> print e
+  where
+    prefixLC = T.toLower prefix
+    filterAddresses :: FilePath -> ConduitT () Void (ResourceT IO) ()
+    filterAddresses dir =
+      CB.sourceFile (dir </> ".addressbook.dat")
+        .| CT.decode CT.utf8
+        .| CT.lines
+        .| C.filter (\v -> prefixLC `T.isPrefixOf` T.toLower v)
+        .| CT.encode CT.utf8
+        .| C.map (<> "\n")
+        .| CB.sinkHandle stdout

src/Control/Addressbook/Streaming.hs

@@ -1,41 +1,73 @@
 module Control.Addressbook.Streaming where
 
-import qualified Data.Text as T
 
 import Conduit
 import qualified Data.Conduit.Binary as CB
 import qualified Data.Conduit.Combinators as C
-import qualified Data.Conduit.Text as CT
+import qualified Data.Conduit.List as CL
 
 import Data.Email
 import Data.Email.Header
        (Header(..))
 
-import System.IO
-       (stdin)
 
 import qualified Data.Foldable as F
 
-import qualified Data.Set as S
+
+import Data.Maybe
+       (fromMaybe)
+import System.Environment
+       (lookupEnv)
+import System.FilePath
+       ((</>))
+import Data.Set (Set)
+import Data.ByteString (ByteString)
+import qualified Data.Set as Set
+import qualified Data.ByteString.Lazy as LBS
+import Data.Char (ord)
+import qualified Data.ByteString.Lazy.Char8 as LBC
+import System.IO.Unsafe (unsafeInterleaveIO)
+import Control.Parallel.Strategies (rseq, parMap)
+import qualified Data.List as L
+import Control.Monad (unless)
+import System.Posix (touchFile)
 
 combine :: (MonadUnliftIO m, MonadResource m, MonadThrow m, MonadIO m) => ConduitM FilePath Header m ()
 combine = await >>= \case
   Nothing -> pure ()
   Just path -> (CB.sourceFile path .| parseEmail) >> combine
 
+chunks :: Int -> [a] -> [[a]]
+chunks n = L.unfoldr $ \case
+  [] -> Nothing
+  xs -> Just (splitAt n xs)
+
 run :: IO ()
 run = do
-  x <- runResourceT $ runConduit stream
+  datDir <- fromMaybe "./" <$> lookupEnv "HOME"
-  F.for_ x print
+  let datFile = datDir </> ".addressbook.dat"
+  touchFile datFile
+  original <- Set.fromList . map LBS.toStrict . lbsLines <$> LBS.readFile datFile
+  xs <- LBS.getContents >>= stream
+  let set = original `Set.union` F.fold (parMap rseq F.fold (chunks 200 xs))
+  unless (original == set) $
+    runResourceT $
+      runConduit $
+           CL.sourceList (Set.elems set)
+        .| C.map (<> "\n")
+        .| CB.sinkFileCautious datFile
   where
     separate = \case
       From x -> [x]
       To xs -> F.toList xs
+    -- A set of (locally) unique addresses. Composes with parMap
+    lbsLines = LBS.split (fromIntegral $ ord '\n')
+    stream :: LBS.ByteString -> IO [Set ByteString]
     stream =
-      CB.sourceHandle stdin
+        traverse (unsafeInterleaveIO . parse . LBC.unpack)
-        .| CT.decode CT.utf8
+      . filter (not . LBS.null)
-        .| CT.lines
+      . lbsLines
-        .| C.map T.unpack
+    parse path =
-        .| combine
+      runResourceT $
-        .| C.concatMap separate
+        runConduit $
-        .| C.foldMap (S.singleton)
+          CB.sourceFile path .| parseEmail .| C.concatMap separate .| C.foldMap Set.singleton

src/Data/Email.hs

@@ -5,12 +5,9 @@ import Data.Email.Header
 
 import Conduit
 import qualified Data.Conduit.Combinators as C
-import qualified Data.Conduit.Text as CT
 
 import Data.ByteString
        (ByteString)
 
 parseEmail :: (MonadUnliftIO m, MonadThrow m, Monad m) => ConduitM ByteString Header m ()
-parseEmail = catchC (CT.decode CT.utf8) err .| CT.lines .| C.concatMap decode
+parseEmail = C.linesUnboundedAscii .| C.concatMap decode
-  where
-    err e = liftIO (print @CT.TextException e) >> yield ""

src/Data/Email/Header.hs

@@ -1,55 +1,63 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ApplicativeDo #-}
 module Data.Email.Header where
 
-import Data.Text
-       (Text)
-import qualified Data.Text as T
-
 import qualified Data.Foldable as F
 
-import Data.Attoparsec.Text
+import Data.Attoparsec.ByteString.Char8
 
 import Data.Vector
        (Vector)
 import qualified Data.Vector as V
 
-import Data.Char
-       (isSpace)
-
 import Control.Applicative
        ((<|>))
+import Data.ByteString (ByteString)
+import qualified Data.ByteString.Char8 as BC
 
 data Header
-  = From !Text
+  = From !ByteString
-  | To !(Vector Text)
+  | To !(Vector ByteString)
   deriving (Show, Eq)
 
-decode :: Text -> Either String Header
+decode :: ByteString -> Either String Header
 decode = parseOnly parseHeader
-  where
+{-# INLINE decode #-}
+
 parseHeader :: Parser Header
 parseHeader = parseFrom <|> parseTo
+{-# INLINE parseHeader #-}
+
 parseFrom :: Parser Header
 parseFrom = From <$> (string "From:" *> emptySpace *> (bracketEmail <|> email))
+
 parseTo :: Parser Header
 parseTo = To <$> (string "To:" *> emptySpace *> emails)
-    emptySpace = many' space
+
-    emails :: Parser (Vector Text)
+emptySpace :: Parser ()
+emptySpace = () <$ many' space
+
+emails :: Parser (Vector ByteString)
 emails = V.fromList <$> (bracketEmail <|> email) `sepBy` char ','
-    bracketEmail :: Parser Text
+
+bracketEmail :: Parser ByteString
 bracketEmail = do
   _ <- manyTill anyChar (char '<')
-      T.pack <$> manyTill anyChar (char '>')
+  email
-    email :: Parser Text
+{-# INLINE bracketEmail #-}
+
+email :: Parser ByteString
 email = do
   _ <- many' space
-      name <- T.pack <$> many' (notChar '@')
+  name <- BC.pack <$> many' (satisfy (\c -> not (isSpace c) && c /= '@'))
   _ <- char '@'
-      rest <- T.pack <$> many' (satisfy (\c -> not (isSpace c) && c /= ','))
+  rest <- BC.pack <$> many' (satisfy (\c -> not (isSpace c) && c /= ',' && c /= '>' && c /= '<'))
   _ <- many' (notChar ',')
   pure (name <> "@" <> rest)
+{-# INLINE email #-}
 
 
-encode :: Header -> Text
+encode :: Header -> ByteString
 encode = \case
   From addr -> "From: " <> addr
-  To addrs -> "To: " <> T.intercalate ", " (F.toList addrs)
+  To addrs -> "To: " <> BC.intercalate ", " (F.toList addrs)

src/Data/Trie.hs

@@ -0,0 +1,87 @@
+-- The bytestring-trie is marked as broken. Trie is a simple(ish) datastructure, implement one here
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE DeriveFunctor #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE DeriveFoldable #-}
+module Data.Trie where
+import Data.ByteString (ByteString)
+import Data.Word (Word8)
+import Data.Foldable (foldl')
+import Data.Semigroup (Last(..))
+import qualified Data.ByteString as B
+import Data.Coerce (coerce)
+import Data.IntMap (IntMap)
+import qualified Data.IntMap.Strict as M
+
+data Pair a b = Pair !a !b
+  deriving (Functor, Foldable)
+
+data Trie a
+  = Empty
+  | Branch !(Maybe (Pair ByteString a)) !(IntMap (Trie a))
+  deriving (Functor, Foldable)
+
+instance Semigroup a => Semigroup (Trie a) where
+  (<>) = union
+
+instance Monoid a => Monoid (Trie a) where
+  mempty = Empty
+
+instance Show a => Show (Trie a) where
+  show = show . toList
+
+keys :: Trie a -> [ByteString]
+keys Empty = []
+keys (Branch Nothing m) = concatMap keys (M.elems m)
+keys (Branch (Just (Pair b _)) m) = b : concatMap keys (M.elems m)
+
+union :: Semigroup a => Trie a -> Trie a -> Trie a
+union Empty r = r
+union l Empty = l
+union (Branch m_pa cl) (Branch ma cr) = Branch (merge m_pa ma) (M.unionWith union cl cr)
+  where
+    merge (Just (Pair x a)) (Just (Pair _ b)) = Just $ Pair x (a <> b)
+    merge Nothing r = r
+    merge l Nothing = l
+
+unionR :: forall a. Trie a -> Trie a -> Trie a
+unionR a b = coerce @(Trie (Last a)) $ union (coerce a) (coerce b)
+
+singleton :: forall a. ByteString -> a -> Trie a
+singleton bs a = go (B.uncons bs)
+  where
+    go :: Maybe (Word8, ByteString) -> Trie a
+    go Nothing =
+      let x = Pair bs a
+      in x `seq` Branch (Just (Pair bs a)) M.empty
+    go (Just (w,c)) =
+      let y = M.singleton (fromIntegral w) (go (B.uncons c))
+      in y `seq` Branch Nothing y
+
+empty :: Trie a
+empty = Empty
+
+elems :: Trie a -> [a]
+elems = foldr (:) []
+
+submap :: forall a. ByteString -> Trie a -> Trie a
+submap bs = go (B.uncons bs)
+  where
+    go :: Maybe (Word8, ByteString) -> Trie a -> Trie a
+    go _ Empty = Empty
+    go Nothing t = t
+    go (Just (w,cs)) (Branch _ c) = maybe empty (go (B.uncons cs)) $ M.lookup (fromIntegral w) c
+
+insert :: forall a. ByteString -> a -> Trie a -> Trie a
+insert bs a = (`unionR` singleton bs a)
+
+fromList :: [(ByteString, a)] -> Trie a
+fromList = foldl' (\acc (k,v) -> insert k v acc) empty
+
+toList :: forall a. Trie a -> [(ByteString, a)]
+toList = go
+  where
+    go :: Trie a -> [(ByteString, a)]
+    go Empty = []
+    go (Branch Nothing m) = concatMap (\(_, child) -> go child) (M.toList m)
+    go (Branch (Just (Pair a b)) m) = (a, b) : concatMap (\(_, child) -> go child) (M.toList m)

test/MyLibTest.hs

@@ -4,11 +4,13 @@ import Test.Tasty
 
 import qualified Test.Data.Email as Data.Email
 import qualified Test.Data.Email.Header as Data.Email.Header
+import qualified Test.Data.Trie as Data.Trie
 
 tests :: TestTree
 tests = testGroup "tests"
   [ Data.Email.Header.tests
   , Data.Email.tests
+  , Data.Trie.tests
   ]
 
 main :: IO ()

test/Test/Data/Email.hs

@@ -17,9 +17,11 @@ sample :: ByteString
 sample =
   "Subject: Hello worldddd\n\
   \From: me@example.com\n\
+  \Dkim: asd\n\
   \To: you <you@example.com>\n\
   \\n\n\
-  \foo"
+  \From: foo bar <a mailto=\"me2@example.com\" />\n\
+  \asd\n"
 
 parseToList :: ByteString -> IO [Header]
 parseToList _ = runConduit (CB.sourceLbs sample .| parseEmail .| CL.consume)
@@ -29,4 +31,7 @@ tests = testGroup "Data.Email"
   [ testCase "Can parse a sample email" $ do
       got <- parseToList sample
       got @?= [ From "me@example.com", To ["you@example.com"]]
+  , testCase "Combined mailto" $ do
+      let got = decode "To: James Doe<james.doe@example.com<mailto:james.doe@example.com>>"
+      got @?= Right (To ["james.doe@example.com"])
   ]

test/Test/Data/Email/Header.hs

@@ -10,11 +10,12 @@ import qualified Hedgehog.Corpus as Corpus
 import qualified Hedgehog.Gen as Gen
 import qualified Hedgehog.Range as Range
 
-import Data.Text
+import Data.ByteString
-import qualified Data.Text as T
+import qualified Data.ByteString as T
 import qualified Data.Vector as V
 
 import Data.Email.Header
+import qualified Data.ByteString.Char8 as BC
 
 genHeader :: Gen Header
 genHeader = Gen.choice
@@ -22,17 +23,17 @@ genHeader = Gen.choice
   , To . V.fromList <$> Gen.list (Range.linear 0 10) genEmail
   ]
 
-genEmail :: Gen Text
+genEmail :: Gen ByteString
 genEmail = do
   name <- Gen.element Corpus.simpsons
   domain <- Gen.element Corpus.cooking
   tld <- Gen.element ["com","fi","org"]
   pure $ name <> "@" <> domain <> "." <> tld
 
-wrapped :: Char -> Text -> Char -> Text
+wrapped :: Char -> ByteString -> Char -> ByteString
-wrapped l x r = T.singleton l <> x <> T.singleton r
+wrapped l x r = BC.singleton l <> x <> BC.singleton r
 
-genComment :: Gen Text
+genComment :: Gen ByteString
 genComment = do
   x <- Gen.element Corpus.simpsons
   Gen.element [x, wrapped '"' x '"']

test/Test/Data/Trie.hs

@@ -0,0 +1,45 @@
+module Test.Data.Trie where
+
+import Test.Tasty
+import Test.Tasty.Hedgehog (testProperty)
+import Hedgehog
+import Data.Monoid (Sum(..))
+import Data.ByteString (ByteString)
+import Data.Map (Map)
+import qualified Hedgehog.Gen as Gen
+import qualified Hedgehog.Range as Range
+import qualified Data.Trie as T
+import qualified Data.Map.Strict as M
+
+genMap :: Gen (Map ByteString (Sum Int))
+genMap = Gen.map (Range.linear 0 100) genT
+  where
+    genT = (,) <$> Gen.bytes (Range.linear 0 20) <*> fmap Sum (Gen.integral (Range.linear 0 10))
+
+propIsomorphic :: Property
+propIsomorphic = property $ do
+  m <- forAll genMap
+  let wanted = m
+      got = M.fromList . T.toList . T.fromList . M.toList $ wanted
+  wanted === got
+
+propElems :: Property
+propElems = property $ do
+  m <- forAll genMap
+  let wanted = M.elems m
+      got = T.elems . T.fromList . M.toList $ m
+  wanted === got
+
+propKeys :: Property
+propKeys = property $ do
+  m <- forAll genMap
+  let wanted = M.keys m
+      got = T.keys . T.fromList . M.toList $ m
+  wanted === got
+
+tests :: TestTree
+tests = testGroup "Data.Trie"
+  [ testProperty "isomorphic to Map" $ propIsomorphic
+  , testProperty "isomorphic elems" $ propElems
+  , testProperty "isomorphic keys" $ propKeys
+  ]