diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,20 @@
 `arch-hs` uses [PVP Versioning][1].
 The changelog is available [on GitHub][2].
 
+## 0.4.0.0
+
+* [Alpm](https://www.archlinux.org/pacman/libalpm.3.html) support
+
+* Fix sub-libraries handling ([#22](https://github.com/berberman/arch-hs/issues/22))
+
+* Fix missing build tools ([#24](https://github.com/berberman/arch-hs/issues/24))
+
+* Fix flag comparison in diff ([#25](https://github.com/berberman/arch-hs/issues/25))
+
+* Fix pretty printing of flags
+
+* Update name preset ([#26](https://github.com/berberman/arch-hs/pull/26))
+
 ## 0.3.0.0
 
 * Update name preset
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@
 
 ## Prerequisite
 
-`arch-hs` is just a PKGBUILD text file generator, which is not integrated with `pacman`, depending on nothing than:
+`arch-hs` is a PKGBUILD text file generator, which is not integrated with `pacman`(See [Alpm Support](#Alpm-Support)), depending on nothing than:
 
 * Pacman database (`community.db`)
 
@@ -28,8 +28,9 @@
 
 ## Installation
 
-Both `arch-hs` and `arch-hs-diff` are portable, which means that they are not restricted to Arch Linux.
-However, if you want to run them in other systems, you have to build them from source.
+`arch-hs` is portable, which means it's not restricted to Arch Linux.
+However, `arch-hs` can use libalpm to load pacman database on Arch Linux,
+and if you want to run them on other systems, you have to build it from source.
 
 ### Install the latest release
 
@@ -238,43 +239,13 @@
 
 See [uusi](https://hackage.haskell.org/package/uusi) for details.
 
-### Help
+### Alpm
 
 ```
-$ arch-hs --help
-arch-hs - a program generating PKGBUILD for hackage packages.
-
-Usage: arch-hs [-h|--hackage PATH] [-c|--community PATH] [-o|--output PATH] 
-               [-f|--flags package_name:flag_name:true|false,...] 
-               [-s|--skip component_name,...] [-e|--extra PATH_1,...] [-a|--aur]
-               [--trace] [--trace-file PATH] [--uusi] TARGET
-  Try to reach the TARGET QAQ.
-
-Available options:
-  -h,--hackage PATH        Path to hackage index
-                           tarball (default: "~/.cabal/packages/YOUR_HACKAGE_MIRROR/01-index.tar | 00-index.tar")
-  -c,--community PATH      Path to
-                           community.db (default: "/var/lib/pacman/sync/community.db")
-  -o,--output PATH         Output path to generated PKGBUILD files (empty means
-                           dry run)
-  -f,--flags package_name:flag_name:true|false,...
-                           Flag assignments for packages - e.g.
-                           inline-c:gsl-example:true (separated by ',')
-  -s,--skip component_name,...
-                           Skip a runnable component (executable, test suit, or
-                           benchmark) in dependency calculation
-  -e,--extra PATH_1,...    Extra cabal files' path - e.g.
-                           /home/berberman/arch-hs/arch-hs.cabal
-  -a,--aur                 Enable AUR searching
-  --trace                  Print trace to stdout
-  --trace-file PATH        Path to trace file (empty means do not write trace to
-                           file)
-  --uusi                   Splicing uusi into prepare()
-  -h,--help                Show this help text
-
+$ arch-hs --alpm TARGET
 ```
 
-For all available options, have a look at the help message.
+See [Alpm Support](#Alpm-Support).
 
 
 ## [Name preset](https://github.com/berberman/arch-hs/blob/master/data/NAME_PRESET.json)
@@ -379,6 +350,21 @@
 
 * Currently, `arch-hs`'s functionality is limited to dependency processing, whereas necessary procedures like
 file patches, loose of version constraints, etc. are need to be done manually, so **DO NOT** give too much trust in generated PKGBUILD files.
+
+## Alpm Support
+
+[alpm](https://www.archlinux.org/pacman/libalpm.3.html) is Arch Linux Package Management library.
+When running on Arch Linux, loading `community.db` through this library is slightly faster than using the internal parser of `arch-hs`.
+Thus, `arch-hs` provides a flag `alpm` to enable this feature:
+
+```
+cabal build -f alpm
+```
+
+This flag is enabled by default in `arch-hs` Arch Linux package.
+Compiled with `alpm`, `arch-hs` can accpet runtime flag `--alpm`.
+**That said, if you want to use alpm to boost `arch-hs`, you need compile `arch-hs` with cabal flag `alpm`, and pass `--aplm` to `arch-hs` when running.**
+> When `alpm` is enabled, `arch-hs` will lose the capability of specifying the path of `community.db`.
 
 ## ToDoList
 
diff --git a/app/Args.hs b/app/Args.hs
--- a/app/Args.hs
+++ b/app/Args.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE DerivingStrategies #-}
 {-# LANGUAGE OverloadedStrings #-}
 
@@ -14,7 +15,9 @@
 
 data Options = Options
   { optHackagePath :: FilePath,
+#ifndef ALPM
     optCommunityPath :: FilePath,
+#endif
     optOutputDir :: FilePath,
     optFlags :: FlagAssignments,
     optSkip :: [String],
@@ -23,6 +26,10 @@
     optStdoutTrace :: Bool,
     optFileTrace :: FilePath,
     optUusi :: Bool,
+    optMetaDir :: FilePath,
+#ifdef ALPM
+    optAlpm :: Bool,
+#endif
     optTarget :: PackageName
   }
   deriving stock (Show)
@@ -38,6 +45,7 @@
           <> showDefault
           <> value "~/.cabal/packages/YOUR_HACKAGE_MIRROR/01-index.tar | 00-index.tar"
       )
+#ifndef ALPM
       <*> strOption
         ( long "community"
             <> metavar "PATH"
@@ -46,6 +54,7 @@
             <> showDefault
             <> value "/var/lib/pacman/sync/community.db"
         )
+#endif
       <*> strOption
         ( long "output"
             <> metavar "PATH"
@@ -94,8 +103,20 @@
         )
       <*> switch
         ( long "uusi"
-            <> help "Splicing uusi into prepare()"
+            <> help "Splice uusi into prepare()"
         )
+      <*> strOption
+        ( long "meta"
+            <> metavar "PATH"
+            <> help "Path to target meta package"
+            <> value ""
+        )
+#ifdef ALPM
+      <*> switch
+        ( long "alpm"
+            <> help "Use libalpm to parse community db"
+        )
+#endif
       <*> argument optPackageNameReader (metavar "TARGET")
 
 runArgsParser :: IO Options
diff --git a/app/Main.hs b/app/Main.hs
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE DerivingStrategies #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
@@ -10,7 +11,8 @@
 import Args
 import qualified Colourista as C
 import Conduit
-import Control.Monad (filterM)
+import Control.Monad (filterM, unless)
+import Data.Containers.ListUtils (nubOrd)
 import Data.IORef (IORef, newIORef)
 import Data.List.NonEmpty (toList)
 import qualified Data.Map.Strict as Map
@@ -18,38 +20,18 @@
 import qualified Data.Text as T
 import Distribution.ArchHs.Aur (Aur, aurToIO, isInAur)
 import Distribution.ArchHs.Community
-  ( defaultCommunityPath,
-    isInCommunity,
-    loadProcessedCommunity,
-  )
 import Distribution.ArchHs.Core
-  ( cabalToPkgBuild,
-    getDependencies,
-  )
 import Distribution.ArchHs.Exception
 import Distribution.ArchHs.Hackage
-  ( getPackageFlag,
-    insertDB,
-    loadHackageDB,
-    lookupHackagePath,
-    parseCabalFile,
-  )
 import Distribution.ArchHs.Internal.Prelude
 import Distribution.ArchHs.Local
+import Distribution.ArchHs.Name
 import Distribution.ArchHs.PP
-  ( prettyDeps,
-    prettyFlagAssignments,
-    prettyFlags,
-    prettySkip,
-    prettySolvedPkgs,
-  )
 import qualified Distribution.ArchHs.PkgBuild as N
 import Distribution.ArchHs.Types
-import Distribution.ArchHs.Utils (getTwo)
-import Distribution.Hackage.DB (HackageDB)
+import Distribution.ArchHs.Utils
 import System.Directory
   ( createDirectoryIfMissing,
-    doesFileExist,
   )
 import System.FilePath (takeFileName)
 
@@ -60,24 +42,24 @@
   Bool ->
   [String] ->
   Bool ->
+  FilePath ->
   Sem r ()
-app target path aurSupport skip uusi = do
-  (deps, ignored) <- getDependencies (fmap mkUnqualComponentName skip) Nothing target
+app target path aurSupport skip uusi metaPath = do
+  (deps, sublibs) <- getDependencies (fmap mkUnqualComponentName skip) Nothing target
   inCommunity <- isInCommunity target
   when inCommunity $ throw $ TargetExist target ByCommunity
 
-  if aurSupport
-    then do
-      inAur <- isInAur target
-      when inAur $ throw $ TargetExist target ByAur
-    else return ()
-
-  let grouped = groupDeps deps
+  when aurSupport $ do
+    inAur <- isInAur target
+    when inAur $ throw $ TargetExist target ByAur
+  let removeSublibs list =
+        list ^.. each . filtered (\x -> x ^. pkgName `notElem` sublibs) & each %~ (\x -> x & pkgDeps %~ (filter (\d -> d ^. depName `notElem` sublibs)))
+      grouped = removeSublibs $ groupDeps deps
       namesFromSolved x = x ^.. each . pkgName <> x ^.. each . pkgDeps . each . depName
-      allNames = nub $ namesFromSolved grouped
+      allNames = nubOrd $ namesFromSolved grouped
   communityProvideList <- (<> ghcLibList) <$> filterM isInCommunity allNames
   let fillProvidedPkgs provideList provider = mapC (\x -> if (x ^. pkgName) `elem` provideList then ProvidedPackage (x ^. pkgName) provider else x)
-      fillProvidedDeps provideList provider = mapC (pkgDeps %~ each %~ (\y -> if y ^. depName `elem` provideList then y & depProvider .~ (Just provider) else y))
+      fillProvidedDeps provideList provider = mapC (pkgDeps %~ each %~ (\y -> if y ^. depName `elem` provideList then y & depProvider ?~ provider else y))
       filledByCommunity =
         runConduitPure $
           yieldMany grouped
@@ -87,7 +69,7 @@
       toBePacked1 = filledByCommunity ^.. each . filtered (\case ProvidedPackage _ _ -> False; _ -> True)
   (filledByBoth, toBePacked2) <- do
     embed . when aurSupport $ C.infoMessage "Start searching AUR..."
-    aurProvideList <- if aurSupport then filterM (\n -> do embed $ C.infoMessage ("Searching " <> (T.pack $ unPackageName n)); isInAur n) $ toBePacked1 ^.. each . pkgName else return []
+    aurProvideList <- if aurSupport then filterM (\n -> do embed $ C.infoMessage ("Searching " <> T.pack (unPackageName n)); isInAur n) $ toBePacked1 ^.. each . pkgName else return []
     let filledByBoth =
           if aurSupport
             then
@@ -103,31 +85,29 @@
             else toBePacked1
     return (filledByBoth, toBePacked2)
 
-  embed $ C.infoMessage "Solved target:"
+  embed $ C.infoMessage "Solved:"
   embed $ putStrLn . prettySolvedPkgs $ filledByBoth
 
-  embed $ C.infoMessage "Recommended package order (from topological sort):"
+  embed $ C.infoMessage "Recommended package order:"
   let vertexesToBeRemoved = filledByBoth ^.. each . filtered (\case ProvidedPackage _ _ -> True; _ -> False) ^.. each . pkgName
       removeSelfCycle g = foldr (\n acc -> GL.removeEdge n n acc) g $ toBePacked2 ^.. each . pkgName
       newGraph = GL.induce (`notElem` vertexesToBeRemoved) deps
-  flattened <- case G.topSort . GL.skeleton $ removeSelfCycle $ newGraph of
+  flattened <- case G.topSort . GL.skeleton $ removeSelfCycle newGraph of
     Left c -> throw . CyclicExist $ toList c
-    Right x -> return x
+    Right x -> return $ filter (`notElem` sublibs) x
   embed $ putStrLn . prettyDeps . reverse $ flattened
-  flags <- filter (\(_, l) -> length l /= 0) <$> mapM (\n -> (n,) <$> getPackageFlag n) flattened
+  flags <- filter (\(_, l) -> not $ null l) <$> mapM (\n -> (n,) <$> getPackageFlag n) flattened
 
   embed $
-    when (length flags /= 0) $ do
-      C.infoMessage "Detected flags from targets (their values will keep default unless you specify):"
+    unless (null flags) $ do
+      C.infoMessage "Detected flag(s) from targets:"
       putStrLn . prettyFlags $ flags
 
-  let dry = path == ""
-  embed $ when dry $ C.warningMessage "You didn't pass -o, PKGBUILD files will not be generated."
-  when (not dry) $
+  unless (null path) $
     mapM_
       ( \solved -> do
-          pkgBuild <- cabalToPkgBuild solved (Set.toList ignored) uusi
-          let pName = "haskell-" <> N._pkgName pkgBuild
+          pkgBuild <- cabalToPkgBuild solved uusi
+          let pName = N._pkgName pkgBuild
               dir = path </> pName
               fileName = dir </> "PKGBUILD"
               txt = N.applyTemplate pkgBuild
@@ -137,6 +117,31 @@
       )
       toBePacked2
 
+  unless (null metaPath) $ do
+    cabal <- getLatestCabal target
+    let url = getUrl $ packageDescription cabal
+        name = unPackageName target
+        template = N.metaTemplate (T.pack url) (T.pack name)
+        providedDepends pkg =
+          pkg ^. pkgDeps
+            ^.. each
+              . filtered (\x -> depNotMyself (pkg ^. pkgName) x && depNotInGHCLib x && x ^. depProvider == Just ByCommunity)
+        toStr x = "'" <> (unCommunityName . toCommunityName . _depName) x <> "'"
+        depends = case intercalate " " . nubOrd . fmap toStr . mconcat $ providedDepends <$> toBePacked2 of
+          [] -> ""
+          xs -> " " <> xs
+        flattened' = filter (/= target) flattened
+        comment = case flattened' of
+          [] -> "\n"
+          [x] -> "# The following dependency is missing in community: " <> unPackageName x
+          _ -> "# Following dependencies are missing in community:" <> (intercalate ", " $ unPackageName <$> flattened')
+        txt = template (T.pack comment) (T.pack depends)
+        dir = metaPath </> "haskell-" <> name <> "-meta"
+        fileName = dir </> "PKGBUILD"
+    embed $ createDirectoryIfMissing True dir
+    embed $ writeFile fileName (T.unpack txt)
+    embed $ C.infoMessage $ "Write file: " <> T.pack fileName
+
 -----------------------------------------------------------------------------
 
 runApp ::
@@ -148,13 +153,13 @@
   IORef (Set.Set PackageName) ->
   Sem '[CommunityEnv, HackageEnv, FlagAssignmentsEnv, DependencyRecord, Trace, State (Set.Set PackageName), Aur, WithMyErr, Embed IO, Final IO] a ->
   IO (Either MyException a)
-runApp hackage community flags stdout path ref =
+runApp hackage community flags traceStdout tracePath ref =
   runFinal
     . embedToFinal
     . errorToIOFinal
     . aurToIO
     . runStateIORef ref
-    . runTrace stdout path
+    . runTrace traceStdout tracePath
     . evalState Map.empty
     . runReader flags
     . runReader hackage
@@ -164,7 +169,7 @@
 runTrace stdout path = interpret $ \case
   Trace m -> do
     when stdout (embed $ putStrLn m)
-    when (not $ null path) (embed $ appendFile path (m ++ "\n"))
+    unless (null path) (embed $ appendFile path (m ++ "\n"))
 
 -----------------------------------------------------------------------------
 
@@ -173,28 +178,26 @@
   do
     Options {..} <- runArgsParser
 
-    let traceToFile = not $ null optFileTrace
-    when (traceToFile) $ do
-      C.infoMessage $ "Trace will be dumped to " <> (T.pack optFileTrace) <> "."
-      exist <- doesFileExist optFileTrace
-      when exist $
-        C.warningMessage $ "File " <> (T.pack optFileTrace) <> " already existed, overwrite it."
-
-    let useDefaultHackage = isInfixOf "YOUR_HACKAGE_MIRROR" $ optHackagePath
-        useDefaultCommunity = "/var/lib/pacman/sync/community.db" == optCommunityPath
+    unless (null optFileTrace) $
+      C.infoMessage $ "Trace will be dumped to " <> T.pack optFileTrace <> "."
 
+    let useDefaultHackage = "YOUR_HACKAGE_MIRROR" `isInfixOf` optHackagePath
     when useDefaultHackage $ C.skipMessage "You didn't pass -h, use hackage index file from default path."
+
+#ifndef ALPM
+    let useDefaultCommunity = "/var/lib/pacman/sync/community.db" == optCommunityPath
     when useDefaultCommunity $ C.skipMessage "You didn't pass -c, use community db file from default path."
+#endif
 
-    let isFlagEmpty = optFlags == Map.empty
-        isSkipEmpty = optSkip == []
+    let isFlagEmpty = Map.null optFlags
+        isSkipEmpty = null optSkip
 
     when isFlagEmpty $ C.skipMessage "You didn't pass -f, different flag assignments may make difference in dependency resolving."
-    when (not isFlagEmpty) $ do
+    unless isFlagEmpty $ do
       C.infoMessage "You assigned flags:"
       putStrLn . prettyFlagAssignments $ optFlags
 
-    when (not isSkipEmpty) $ do
+    unless isSkipEmpty $ do
       C.infoMessage "You chose to skip:"
       putStrLn $ prettySkip optSkip
 
@@ -205,23 +208,29 @@
     hackage <- loadHackageDB =<< if useDefaultHackage then lookupHackagePath else return optHackagePath
     C.infoMessage "Loading hackage..."
 
-    let isExtraEmpty = optExtraCabalPath == []
+    let isExtraEmpty = null optExtraCabalPath
 
-    when (not isExtraEmpty) $
+    unless isExtraEmpty $
       C.infoMessage $ "You added " <> (T.pack . intercalate ", " $ map takeFileName optExtraCabalPath) <> " as extra cabal file(s), starting parsing right now."
 
     parsedExtra <- mapM parseCabalFile optExtraCabalPath
 
-    let newHackage = foldr (\x acc -> x `insertDB` acc) hackage parsedExtra
+    let newHackage = foldr insertDB hackage parsedExtra
 
+#ifdef ALPM
+    when optAlpm $ C.infoMessage "Using alpm."
+    community <- if optAlpm then loadCommunityFFI else loadProcessedCommunity defaultCommunityPath
+#else
     community <- loadProcessedCommunity $ if useDefaultCommunity then defaultCommunityPath else optCommunityPath
+#endif
+
     C.infoMessage "Loading community.db..."
 
     C.infoMessage "Start running..."
 
     empty <- newIORef Set.empty
 
-    runApp newHackage community optFlags optStdoutTrace optFileTrace empty (app optTarget optOutputDir optAur optSkip optUusi) & printAppResult
+    runApp newHackage community optFlags optStdoutTrace optFileTrace empty (app optTarget optOutputDir optAur optSkip optUusi optMetaDir) & printAppResult
 
 -----------------------------------------------------------------------------
 
@@ -242,4 +251,4 @@
     parents = fmap fst result
     children = mconcat $ fmap (\(_, ds) -> fmap snd ds) result
     -- Maybe 'G.vertexSet' is a better choice
-    aloneChildren = nub $ zip (filter (`notElem` parents) children) (repeat [])
+    aloneChildren = nubOrd $ zip (filter (`notElem` parents) children) (repeat [])
diff --git a/arch-hs.cabal b/arch-hs.cabal
--- a/arch-hs.cabal
+++ b/arch-hs.cabal
@@ -1,127 +1,135 @@
-cabal-version:       2.4
-name:                arch-hs
-version:             0.3.0.0
-synopsis:            Distribute hackage packages to archlinux
-description:         
-    @arch-hs@ is a command-line program, which simplifies the process of producing
-    and maintaining haskell packages for archlinux distribution by automating the
-    PKGBUILD generation with the dependency resolving and template filling. Currently,
-    @arch-hs@ is unstable, so packagers should not trust it 100%, but always follow the
-    <https://wiki.archlinux.org/index.php/Haskell_package_guidelines Haskell package guidelines>.
-homepage:            https://github.com/berberman/arch-hs
-bug-reports:         https://github.com/berberman/arch-hs/issues
-license:             MIT
-license-file:        LICENSE
-author:              berberman
-maintainer:          berberman <1793913507@qq.com>
-copyright:           2020 berberman
-category:            Distribution
-build-type:          Simple
-extra-source-files:  data/NAME_PRESET.json
-extra-doc-files:     README.md
-                     CHANGELOG.md
-tested-with:         GHC == 8.10.2
+cabal-version:      2.4
+name:               arch-hs
+version:            0.4.0.0
+synopsis:           Distribute hackage packages to archlinux
+description:
+  @arch-hs@ is a command-line program, which simplifies the process of producing
+  and maintaining haskell packages for archlinux distribution by automating the
+  PKGBUILD generation with the dependency resolving and template filling. Currently,
+  @arch-hs@ is unstable, so packagers should not trust it 100%, but always follow the
+  <https://wiki.archlinux.org/index.php/Haskell_package_guidelines Haskell package guidelines>.
 
+homepage:           https://github.com/berberman/arch-hs
+bug-reports:        https://github.com/berberman/arch-hs/issues
+license:            MIT
+license-file:       LICENSE
+author:             berberman
+maintainer:         berberman <1793913507@qq.com>
+copyright:          2020 berberman
+category:           Distribution
+build-type:         Simple
+extra-source-files: data/NAME_PRESET.json
+extra-doc-files:
+  CHANGELOG.md
+  README.md
+
+tested-with:        GHC ==8.10.2
+
 source-repository head
-  type:                git
-  location:            https://github.com/berberman/arch-hs.git
+  type:     git
+  location: https://github.com/berberman/arch-hs.git
+
+flag alpm
+  description: Whether to use libalpm
+  default:     False
+  manual:      True
+
 common common-options
-  build-depends:       base ^>= 4.14.0,
-                       Cabal ^>= 3.2.0, 
-                       aeson ^>= 1.5.4,
-                       req ^>= 3.6.0,
-                       hackage-db ^>= 2.1.0,
-                       conduit ^>= 1.3.2,
-                       containers ^>= 0.6.2,
-                       deepseq ^>= 1.4.4,
-                       algebraic-graphs ^>= 0.5,
-                       megaparsec ^>= 8.0.0,
-                       directory ^>= 1.3.6,
-                       bytestring ^>= 0.10.10,
-                       tar-conduit ^>= 0.3.2,
-                       conduit-extra ^>= 1.3.5,
-                       split ^>= 0.2.3,
-                       neat-interpolation ^>= 0.5.1,
-                       text ^>= 1.2.3,
-                       microlens ^>= 0.4.11,
-                       microlens-th ^>= 0.4.3,
-                       polysemy ^>= 1.3.0,
-                       filepath ^>= 1.4.2,
-                       colourista ^>= 0.1,
-                       template-haskell ^>= 2.16.0,
-                       optparse-applicative ^>= 0.15.1
+  build-depends:
+    , aeson                 ^>=1.5.4
+    , algebraic-graphs      ^>=0.5
+    , base                  ^>=4.14.0
+    , bytestring            ^>=0.10.10
+    , Cabal                 ^>=3.2.0
+    , colourista            ^>=0.1
+    , conduit               ^>=1.3.2
+    , conduit-extra         ^>=1.3.5
+    , containers            ^>=0.6.2
+    , deepseq               ^>=1.4.4
+    , directory             ^>=1.3.6
+    , filepath              ^>=1.4.2
+    , hackage-db            ^>=2.1.0
+    , megaparsec            ^>=8.0.0
+    , microlens             ^>=0.4.11
+    , microlens-th          ^>=0.4.3
+    , neat-interpolation    ^>=0.5.1
+    , optparse-applicative  ^>=0.15.1
+    , polysemy              ^>=1.3.0 || ^>=1.4.0
+    , req                   ^>=3.6.0 || ^>=3.7.0
+    , split                 ^>=0.2.3
+    , tar-conduit           ^>=0.3.2
+    , template-haskell      ^>=2.16.0
+    , text                  ^>=1.2.3
 
-  ghc-options:         -Wall
-                       -Wcompat
-                       -Widentities
-                       -Wincomplete-uni-patterns
-                       -Wincomplete-record-updates
-                       -O2 
-                       -flate-specialise 
-                       -fspecialise-aggressively
-                       -Wredundant-constraints
-                       -fhide-source-paths
-                       -Wmissing-export-lists
-                       -Wpartial-fields
-                       -Wmissing-deriving-strategies
+  ghc-options:
+    -Wall -Wcompat -Widentities -Wincomplete-uni-patterns
+    -Wincomplete-record-updates -O2 -flate-specialise
+    -fspecialise-aggressively -Wredundant-constraints
+    -fhide-source-paths -Wmissing-export-lists -Wpartial-fields
+    -Wmissing-deriving-strategies
 
-  default-language:    Haskell2010
-  default-extensions:  DataKinds
-                       FlexibleContexts
-                       GADTs
-                       LambdaCase
-                       PolyKinds
-                       RankNTypes
-                       ScopedTypeVariables
-                       TypeOperators
-                       TypeFamilies
+  default-language:   Haskell2010
+  default-extensions:
+    DataKinds
+    FlexibleContexts
+    GADTs
+    LambdaCase
+    PolyKinds
+    RankNTypes
+    ScopedTypeVariables
+    TypeFamilies
+    TypeOperators
+
+  if flag(alpm)
+    c-sources:        cbits/clib.c
+    extra-libraries:  alpm
+    include-dirs:     cbits
+    install-includes: cbits/clib.h
+    cpp-options:      -DALPM
+
 library
-  import:              common-options
-  hs-source-dirs:      src
-  exposed-modules:     Distribution.ArchHs.Aur,
-                       Distribution.ArchHs.PkgDesc,
-                       Distribution.ArchHs.Community,
-                       Distribution.ArchHs.Core,
-                       Distribution.ArchHs.Hackage,
-                       Distribution.ArchHs.Local,
-                       Distribution.ArchHs.PkgBuild,
-                       Distribution.ArchHs.Types,
-                       Distribution.ArchHs.Utils,
-                       Distribution.ArchHs.PP,
-                       Distribution.ArchHs.Name,
-                       Distribution.ArchHs.Exception,
-                       Distribution.ArchHs.Internal.Prelude
-                       Distribution.ArchHs.OptionReader
-  other-modules:       Data.Aeson.Ext
-                       Distribution.ArchHs.Internal.NamePresetLoader
-                       
+  import:          common-options
+  hs-source-dirs:  src
+  exposed-modules:
+    Distribution.ArchHs.Aur
+    Distribution.ArchHs.Community
+    Distribution.ArchHs.Core
+    Distribution.ArchHs.Exception
+    Distribution.ArchHs.Hackage
+    Distribution.ArchHs.Internal.Prelude
+    Distribution.ArchHs.Local
+    Distribution.ArchHs.Name
+    Distribution.ArchHs.OptionReader
+    Distribution.ArchHs.PkgBuild
+    Distribution.ArchHs.PkgDesc
+    Distribution.ArchHs.PP
+    Distribution.ArchHs.Types
+    Distribution.ArchHs.Utils
 
+  other-modules:
+    Data.Aeson.Ext
+    Distribution.ArchHs.Internal.NamePresetLoader
+
 executable arch-hs
-  import:              common-options
-  hs-source-dirs:      app
-  main-is:             Main.hs
-  other-modules:       Args
-  build-depends:       arch-hs
-  ghc-options:         -threaded
-                       -rtsopts
-                       -with-rtsopts=-N
+  import:         common-options
+  hs-source-dirs: app
+  main-is:        Main.hs
+  other-modules:  Args
+  build-depends:  arch-hs
+  ghc-options:    -threaded -rtsopts -with-rtsopts=-N
 
 executable arch-hs-diff
-  import:              common-options
-  hs-source-dirs:      diff
-  main-is:             Main.hs
-  other-modules:       Diff
-  build-depends:       arch-hs
-  ghc-options:         -threaded
-                       -rtsopts
-                       -with-rtsopts=-N
-                       
+  import:         common-options
+  hs-source-dirs: diff
+  main-is:        Main.hs
+  other-modules:  Diff
+  build-depends:  arch-hs
+  ghc-options:    -threaded -rtsopts -with-rtsopts=-N
+
 executable arch-hs-submit
-  import:              common-options
-  hs-source-dirs:      submit
-  main-is:             Main.hs
-  other-modules:       Submit
-  build-depends:       arch-hs
-  ghc-options:         -threaded
-                       -rtsopts
-                       -with-rtsopts=-N
+  import:         common-options
+  hs-source-dirs: submit
+  main-is:        Main.hs
+  other-modules:  Submit
+  build-depends:  arch-hs
+  ghc-options:    -threaded -rtsopts -with-rtsopts=-N
diff --git a/cbits/clib.c b/cbits/clib.c
new file mode 100644
--- /dev/null
+++ b/cbits/clib.c
@@ -0,0 +1,34 @@
+#include "clib.h"
+#include <alpm.h>
+#include <alpm_list.h>
+#include <stdio.h>
+#include <string.h>
+
+int query_community(callback_t callback) {
+  alpm_errno_t err;
+  alpm_handle_t *handle;
+  handle = alpm_initialize("/", "/var/lib/pacman", &err);
+  alpm_db_t *db =
+      alpm_register_syncdb(handle, "community", ALPM_SIG_USE_DEFAULT);
+  alpm_list_t *i, *pkgs = NULL;
+
+  pkgs = alpm_db_get_pkgcache(db);
+
+  for (i = pkgs; i; i = alpm_list_next(i)) {
+    const char *name = alpm_pkg_get_name(i->data);
+    const char *ver = alpm_pkg_get_version(i->data);
+    if (strcmp(name, "ghc") == 0 || strcmp(name, "ghc-libs") == 0) {
+      alpm_list_t *v, *provides;
+      provides = alpm_pkg_get_provides(i->data);
+      for (v = provides; v; v = alpm_list_next(v)) {
+        alpm_depend_t *d = v->data;
+        const char *d_name = d->name;
+        const char *d_ver = d->version;
+        callback(d_name, d_ver);
+      }
+    } else
+      callback(name, ver);
+  }
+  alpm_release(handle);
+  return err;
+}
diff --git a/cbits/clib.h b/cbits/clib.h
new file mode 100644
--- /dev/null
+++ b/cbits/clib.h
@@ -0,0 +1,8 @@
+#ifndef CLIB_H
+#define CLIB_H
+
+typedef void callback_t(const char *, const char *);
+
+int query_community(callback_t callback);
+
+#endif
diff --git a/data/NAME_PRESET.json b/data/NAME_PRESET.json
--- a/data/NAME_PRESET.json
+++ b/data/NAME_PRESET.json
@@ -10,6 +10,7 @@
     "agda": "Agda",
     "alex": "alex",
     "arch-hs": "arch-hs",
+    "bnfc": "BNFC",
     "c2hs": "c2hs",
     "haskell-cabal": "Cabal",
     "cabal-install": "cabal-install",
diff --git a/diff/Diff.hs b/diff/Diff.hs
--- a/diff/Diff.hs
+++ b/diff/Diff.hs
@@ -1,5 +1,5 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE TupleSections #-}
 {-# LANGUAGE TypeApplications #-}
 
 module Diff
@@ -29,8 +29,12 @@
 import Network.HTTP.Req hiding (header)
 
 data Options = Options
-  { optCommunityPath :: FilePath,
-    optFlags :: FlagAssignments,
+  { optFlags :: FlagAssignments,
+#ifdef ALPM
+    optAlpm :: Bool,
+#else
+    optCommunityPath :: FilePath,
+#endif
     optPackageName :: PackageName,
     optVersionA :: Version,
     optVersionB :: Version
@@ -39,15 +43,7 @@
 cmdOptions :: Parser Options
 cmdOptions =
   Options
-    <$> strOption
-      ( long "community"
-          <> metavar "PATH"
-          <> short 'c'
-          <> help "Path to community.db"
-          <> showDefault
-          <> value "/var/lib/pacman/sync/community.db"
-      )
-    <*> option
+    <$> option
       optFlagReader
       ( long "flags"
           <> metavar "package_name:flag_name:true|false,..."
@@ -55,6 +51,21 @@
           <> help "Flag assignments for packages - e.g. inline-c:gsl-example:true (separated by ',')"
           <> value Map.empty
       )
+#ifndef ALPM
+    <*> strOption
+      ( long "community"
+          <> metavar "PATH"
+          <> short 'c'
+          <> help "Path to community.db"
+          <> showDefault
+          <> value "/var/lib/pacman/sync/community.db"
+      )
+#else
+      <*> switch
+        ( long "alpm"
+            <> help "Use libalpm to parse community db"
+        )
+#endif
     <*> argument optPackageNameReader (metavar "TARGET")
     <*> argument optVersionReader (metavar "VERSION_A")
     <*> argument optVersionReader (metavar "VERSION_B")
@@ -82,8 +93,8 @@
   case cabal & condLibrary of
     Just lib -> do
       bInfo <- evalConditionTree cabal lib
-      let libDeps = fmap unDepV $ buildDependsIfBuild bInfo
-          toolDeps = fmap unExeV $ buildToolDependsIfBuild bInfo
+      let libDeps = unDepV <$> buildDependsIfBuild bInfo
+          toolDeps = unBuildTools $ buildToolsAndbuildToolDependsIfBuild bInfo
       mapM_ (uncurry updateDependencyRecord) libDeps
       mapM_ (uncurry updateDependencyRecord) toolDeps
       return (libDeps, toolDeps)
@@ -98,8 +109,8 @@
 collectRunnableDeps f cabal skip = do
   let exes = cabal & f
   bInfo <- filter (not . (`elem` skip) . fst) . zip (exes <&> fst) <$> mapM (evalConditionTree cabal . snd) exes
-  let deps = bInfo <&> ((_2 %~) $ fmap unDepV . buildDependsIfBuild)
-      toolDeps = bInfo <&> ((_2 %~) $ fmap unExeV . buildToolDependsIfBuild)
+  let deps = bInfo <&> _2 %~ (fmap unDepV . buildDependsIfBuild)
+      toolDeps = bInfo <&> _2 %~ (unBuildTools . buildToolsAndbuildToolDependsIfBuild)
   mapM_ (uncurry updateDependencyRecord) $ deps ^.. each . _2 ^. each
   mapM_ (uncurry updateDependencyRecord) $ toolDeps ^.. each . _2 ^. each
   return (deps, toolDeps)
@@ -141,10 +152,10 @@
       et = flatten exeToolsDeps
       t = flatten testDeps
       tt = flatten testToolsDeps
-      notMyself = (/= (getPkgName' cabal))
+      notMyself = (/= getPkgName' cabal)
       distinct = filter (notMyself . fst) . nub
       depends = distinct $ l <> e
-      makedepends = (distinct $ lt <> et <> t <> tt) \\ depends
+      makedepends = distinct (lt <> et <> t <> tt) \\ depends
   return (depends, makedepends)
 
 -----------------------------------------------------------------------------
@@ -156,7 +167,7 @@
   let pa = packageDescription ga
       pb = packageDescription gb
       fa = genPackageFlags ga
-      fb = genPackageFlags ga
+      fb = genPackageFlags gb
   (ba, ma) <- directDependencies ga
   (bb, mb) <- directDependencies gb
   queryb <- lookupDiffCommunity ba bb
@@ -180,8 +191,8 @@
 diffTerm s f a b =
   let f' = T.unpack . T.strip . T.pack . f
       (ra, rb) = (f' a, f' b)
-   in (C.formatWith [C.magenta] s)
-        <> (if ra == rb then ra else ((C.formatWith [C.red] ra) <> "  ⇒  " <> C.formatWith [C.green] rb))
+   in C.formatWith [C.magenta] s
+        <> (if ra == rb then ra else C.formatWith [C.red] ra <> "  ⇒  " <> C.formatWith [C.green] rb)
 
 desc :: PackageDescription -> PackageDescription -> String
 desc = diffTerm "Synopsis: " $ fromShortText . synopsis
@@ -197,7 +208,7 @@
 
 inRange :: Members [CommunityEnv, WithMyErr] r => (PackageName, VersionRange) -> Sem r (Either (PackageName, VersionRange) (PackageName, VersionRange, Version, Bool))
 inRange (name, hRange) =
-  (try @MyException (versionInCommunity name))
+  try @MyException (versionInCommunity name)
     >>= \case
       Right y -> let version = fromJust . simpleParsec $ y in return . Right $ (name, hRange, version, withinRange version hRange)
       Left _ -> return . Left $ (name, hRange)
@@ -208,22 +219,22 @@
       diffOld = va \\ vb
       color b = C.formatWith [if b then C.green else C.red]
       pp b (Right (name, range, v, False)) =
-        "["
+        "\""
           <> color b (unPackageName name)
-          <> "] is required to be in range ("
+          <> "\" is required to be in range ("
           <> color b (prettyShow range)
           <> "), "
-          <> "but community provides ("
+          <> "but [community] provides ("
           <> color b (prettyShow v)
           <> ")."
       pp _ (Right _) = ""
       pp b (Left (name, range)) =
-        "["
+        "\""
           <> color b (unPackageName name)
-          <> "] is required to be in range ("
+          <> "\" is required to be in range ("
           <> color b (prettyShow range)
           <> "), "
-          <> "but community does not provide this package."
+          <> "but [community] does not provide this package."
 
   new <- fmap (pp True) <$> mapM inRange diffNew
   old <- fmap (pp False) <$> mapM inRange diffOld
@@ -232,13 +243,13 @@
 
 dep :: String -> VersionedList -> VersionedList -> String
 dep s va vb =
-  (C.formatWith [C.magenta] s) <> "    " <> case (diffOld <> diffNew) of
+  C.formatWith [C.magenta] s <> "    " <> case diffOld <> diffNew of
     [] -> joinToString a
     _ ->
-      (joinToString $ fmap (\x -> red (x `elem` diffOld) x) a)
+      joinToString (fmap (\x -> red (x `elem` diffOld) x) a)
         <> splitLine
         <> "    "
-        <> (joinToString $ fmap (\x -> green (x `elem` diffNew) x) b)
+        <> joinToString (fmap (\x -> green (x `elem` diffNew) x) b)
   where
     a = joinVersionWithName <$> va
     b = joinVersionWithName <$> vb
@@ -252,13 +263,13 @@
 
 flags :: PackageName -> [Flag] -> [Flag] -> String
 flags name a b =
-  (C.formatWith [C.magenta] "Flags:\n") <> "  " <> case (diffOld <> diffNew) of
+  C.formatWith [C.magenta] "Flags:\n" <> "  " <> case diffOld <> diffNew of
     [] -> joinToString a
     _ ->
-      (joinToString a)
+      joinToString a
         <> splitLine
         <> "    "
-        <> (joinToString b)
+        <> joinToString b
   where
     diffNew = b \\ a
     diffOld = a \\ b
diff --git a/diff/Main.hs b/diff/Main.hs
--- a/diff/Main.hs
+++ b/diff/Main.hs
@@ -1,16 +1,15 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
 
 module Main (main) where
 
 import qualified Colourista as C
+import Control.Monad (unless)
 import qualified Data.Map as Map
 import qualified Data.Text as T
 import Diff
 import Distribution.ArchHs.Community
-  ( defaultCommunityPath,
-    loadProcessedCommunity,
-  )
 import Distribution.ArchHs.Exception
 import Distribution.ArchHs.Internal.Prelude
 import Distribution.ArchHs.PP (prettyFlagAssignments)
@@ -20,17 +19,25 @@
 main = printHandledIOException $
   do
     Options {..} <- runArgsParser
-    let useDefaultCommunity = "/var/lib/pacman/sync/community.db" == optCommunityPath
-        isFlagEmpty = Map.null optFlags
+    let isFlagEmpty = Map.null optFlags
 
+#ifndef ALPM
+    let useDefaultCommunity = "/var/lib/pacman/sync/community.db" == optCommunityPath
     when useDefaultCommunity $ C.skipMessage "You didn't pass -c, use community db file from default path."
+#endif
 
     when isFlagEmpty $ C.skipMessage "You didn't pass -f, different flag values may make difference in dependency resolving."
-    when (not isFlagEmpty) $ do
+    unless isFlagEmpty $ do
       C.infoMessage "You assigned flags:"
       putStrLn . prettyFlagAssignments $ optFlags
 
+#ifdef ALPM
+    when optAlpm $ C.infoMessage "Using alpm."
+    community <- if optAlpm then loadCommunityFFI else loadProcessedCommunity defaultCommunityPath
+#else
     community <- loadProcessedCommunity $ if useDefaultCommunity then defaultCommunityPath else optCommunityPath
+#endif
+    
     C.infoMessage "Loading community.db..."
 
     C.infoMessage "Start running..."
@@ -39,4 +46,4 @@
       Right r -> putStrLn r >> C.successMessage "Success!"
 
 runDiff :: CommunityDB -> FlagAssignments -> Sem '[CommunityEnv, FlagAssignmentsEnv, Trace, DependencyRecord, WithMyErr, Embed IO, Final IO] a -> IO (Either MyException a)
-runDiff community flags = runFinal . embedToFinal . errorToIOFinal . evalState (Map.empty) . ignoreTrace . (runReader flags) . (runReader community)
+runDiff community flags = runFinal . embedToFinal . errorToIOFinal . evalState Map.empty . ignoreTrace . runReader flags . runReader community
diff --git a/src/Distribution/ArchHs/Aur.hs b/src/Distribution/ArchHs/Aur.hs
--- a/src/Distribution/ArchHs/Aur.hs
+++ b/src/Distribution/ArchHs/Aur.hs
@@ -107,8 +107,6 @@
   InfoByName :: String -> Aur m (Maybe AurInfo)
   IsInAur :: HasMyName n => n -> Aur m Bool
 
--- searchByName
-
 makeSem_ ''Aur
 
 -- | Serach a package from AUR
@@ -130,7 +128,7 @@
           "v" =: ("5" :: Text)
             <> "type" =: ("search" :: Text)
             <> "by" =: ("name" :: Text)
-            <> "arg" =: (pack name)
+            <> "arg" =: pack name
         r = req GET baseURL NoReqBody jsonResponse parms
     response <- interceptHttpException $ runReq defaultHttpConfig r
     let body :: AurReply AurSearch = responseBody response
@@ -142,7 +140,7 @@
           "v" =: ("5" :: Text)
             <> "type" =: ("info" :: Text)
             <> "by" =: ("name" :: Text)
-            <> "arg[]" =: (pack name)
+            <> "arg[]" =: pack name
         r = req GET baseURL NoReqBody jsonResponse parms
     response <- interceptHttpException $ runReq defaultHttpConfig r
     let body :: AurReply AurInfo = responseBody response
diff --git a/src/Distribution/ArchHs/Community.hs b/src/Distribution/ArchHs/Community.hs
--- a/src/Distribution/ArchHs/Community.hs
+++ b/src/Distribution/ArchHs/Community.hs
@@ -1,5 +1,5 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE TypeApplications #-}
 
 -- | Copyright: (c) 2020 berberman
@@ -13,6 +13,10 @@
     loadProcessedCommunity,
     isInCommunity,
     versionInCommunity,
+    compiledWithAlpm,
+#ifdef ALPM
+    loadCommunityFFI,
+#endif
   )
 where
 
@@ -26,7 +30,59 @@
 import Distribution.ArchHs.Name
 import Distribution.ArchHs.PkgDesc
 import Distribution.ArchHs.Types
+import Distribution.ArchHs.Utils
 
+-----------------------------------------------------------------------------
+
+#ifdef ALPM
+{-# LANGUAGE ForeignFunctionInterface #-}
+import qualified Data.Sequence as Seq
+import Data.Foldable (toList)
+import Data.IORef (IORef, modifyIORef', newIORef, readIORef)
+import Foreign.C.String (CString, peekCString)
+import Foreign.C.Types (CInt(..))
+import Foreign.Ptr (FunPtr, freeHaskellFunPtr)
+
+foreign import ccall "wrapper"
+  wrap :: (CString -> CString -> IO ()) -> IO (FunPtr (CString -> CString -> IO ()))
+
+foreign import ccall "clib.h query_community"
+  query_community :: FunPtr (CString -> CString -> IO ()) -> IO CInt
+
+foreign import ccall "alpm.h alpm_strerror"
+  alpm_strerror :: CInt -> IO CString
+
+callback :: IORef (Seq.Seq (CommunityName, CommunityVersion)) -> CString -> CString -> IO ()
+callback ref x y = do
+  x' <- peekCString x
+  y' <- peekCString y
+  modifyIORef' ref (Seq.|> (CommunityName x', extractFromEVR y'))
+
+-- | The same purpose as 'loadCommunity' but use alpm to query community db instead.
+loadCommunityFFI :: IO CommunityDB
+loadCommunityFFI = do
+  ref <- newIORef Seq.empty
+  callbackW <- wrap $ callback ref
+  errno <- query_community callbackW
+  freeHaskellFunPtr callbackW
+  when (errno /= 0) $ do
+    msg <- peekCString =<< alpm_strerror errno
+    -- TODO: why? :(
+    putStrLn $ "warn: unexpected return code from libalpm: " <> show errno <> " (" <> msg <> ")"
+  Map.fromList . toList <$> readIORef ref
+#endif
+
+-- | Whether this program enables alpm support.
+compiledWithAlpm :: Bool
+compiledWithAlpm =
+#ifdef ALPM
+  True
+#else
+  False
+#endif
+
+-----------------------------------------------------------------------------
+
 -- | Default path to @community.db@.
 defaultCommunityPath :: FilePath
 defaultCommunityPath = "/" </> "var" </> "lib" </> "pacman" </> "sync" </> "community.db"
@@ -49,31 +105,28 @@
                     Right r -> case head $ r Map.! "NAME" of
                       "ghc" -> parseProvidedTerm <$> provided r
                       "ghc-libs" -> parseProvidedTerm <$> provided r
-                      _ -> [(head $ r Map.! "NAME", extractVer . head $ r Map.! "VERSION")]
-                    -- TODO: Drop it
+                      _ -> [(head $ r Map.! "NAME", extractFromEVR . head $ r Map.! "VERSION")]
+                    -- Drop it if failed to parse
                     Left _ -> []
-            extractVer ver = head $
-              splitOn "-" $ case splitOn ":" ver of
-                (_ : v : []) -> v
-                v : [] -> v
-                _ -> fail "err"
 
         yieldMany $ result & each . _1 %~ CommunityName
 
 -- | Load @community.db@ from @path@.
 -- @desc@ files in the db will be parsed by @descParser@.
 loadProcessedCommunity :: (MonadUnliftIO m, PrimMonad m, MonadThrow m) => FilePath -> m CommunityDB
-loadProcessedCommunity path = Map.fromList <$> (runConduitRes $ loadCommunity path .| sinkList)
+loadProcessedCommunity path = Map.fromList <$> runConduitRes (loadCommunity path .| sinkList)
 
+-----------------------------------------------------------------------------
+
 -- | Check if a package exists in archlinux community repo.
 -- See 'HasMyName'.
 isInCommunity :: (HasMyName n, Member CommunityEnv r) => n -> Sem r Bool
-isInCommunity name = ask @CommunityDB >>= \db -> return $ (toCommunityName name) `Map.member` db
+isInCommunity name = ask @CommunityDB >>= \db -> return $ toCommunityName name `Map.member` db
 
 -- | Get the version of a package in archlinux community repo.
 -- If the package does not exist, 'PkgNotFound' will be thrown.
 versionInCommunity :: (HasMyName n, Members [CommunityEnv, WithMyErr] r) => n -> Sem r CommunityVersion
 versionInCommunity name =
-  ask @CommunityDB >>= \db -> case db Map.!? (toCommunityName name) of
+  ask @CommunityDB >>= \db -> case db Map.!? toCommunityName name of
     Just x -> return x
     _ -> throw $ PkgNotFound name
diff --git a/src/Distribution/ArchHs/Core.hs b/src/Distribution/ArchHs/Core.hs
--- a/src/Distribution/ArchHs/Core.hs
+++ b/src/Distribution/ArchHs/Core.hs
@@ -15,7 +15,7 @@
 where
 
 import qualified Algebra.Graph.Labelled.AdjacencyMap as G
-import Data.Char (toLower)
+import Data.Bifunctor (second)
 import qualified Data.Map as Map
 import Data.Set (Set)
 import qualified Data.Set as Set
@@ -25,7 +25,7 @@
     getLatestSHA256,
   )
 import Distribution.ArchHs.Internal.Prelude
-import Distribution.ArchHs.Local (ghcLibList, ignoreList)
+import Distribution.ArchHs.Local (ignoreList)
 import Distribution.ArchHs.Name
 import Distribution.ArchHs.PkgBuild
   ( PkgBuild (..),
@@ -77,7 +77,7 @@
         mkFlagAssignment
           . (<> flagAssignment)
           . filter (\(fName, _) -> fName `notElem` flagNames)
-          $ (unFlagAssignment defaultFlagAssignments)
+          $ unFlagAssignment defaultFlagAssignments
   trace' $ "Evaluating condition tree of " <> show name
   trace' $ "Flags: " <> show thisFlag
   traceCallStack
@@ -96,7 +96,7 @@
   Maybe PackageName ->
   -- | Target
   PackageName ->
-  Sem r ((G.AdjacencyMap (Set DependencyType) PackageName), Set PackageName)
+  Sem r (G.AdjacencyMap (Set DependencyType) PackageName, Set PackageName)
 getDependencies skip parent name = do
   resolved <- get @(Set PackageName)
   modify' $ Set.insert name
@@ -104,7 +104,6 @@
   trace' $ "Already resolved: " <> show resolved
   traceCallStack
   cabal <- getLatestCabal name
-  -- Ignore subLibraries
   (libDeps, libToolsDeps) <- collectLibDeps cabal
   (subLibDeps, subLibToolsDeps) <- collectSubLibDeps cabal skip
   (exeDeps, exeToolsDeps) <- collectExeDeps cabal skip
@@ -126,14 +125,14 @@
 
       filteredLibDeps = ignore libDeps
       filteredLibToolsDeps = ignore libToolsDeps
-      filteredExeDeps = ignoreFlatten CExe $ exeDeps
-      filteredExeToolsDeps = ignoreFlatten CExeBuildTools $ exeToolsDeps
-      filteredTestDeps = ignoreFlatten CTest $ testDeps
-      filteredTestToolsDeps = ignoreFlatten CTest $ testToolsDeps
-      filteredSubLibDeps = ignoreFlatten CSubLibs $ subLibDeps
-      filteredSubLibToolsDeps = ignoreFlatten CSubLibsBuildTools $ subLibToolsDeps
+      filteredExeDeps = ignoreFlatten CExe exeDeps
+      filteredExeToolsDeps = ignoreFlatten CExeBuildTools exeToolsDeps
+      filteredTestDeps = ignoreFlatten CTest testDeps
+      filteredTestToolsDeps = ignoreFlatten CTest testToolsDeps
+      filteredSubLibDeps = ignoreFlatten CSubLibs subLibDeps
+      filteredSubLibToolsDeps = ignoreFlatten CSubLibsBuildTools subLibToolsDeps
 
-      filteredSubLibDepsNames = fmap unqualComponentNameToPackageName . fmap fst $ subLibDeps
+      filteredSubLibDepsNames = fmap (unqualComponentNameToPackageName . fst) subLibDeps
       ignoreSubLibs = filter (`notElem` filteredSubLibDepsNames)
       ignoreResolved = filter (`notElem` resolved)
 
@@ -163,7 +162,7 @@
   let temp = [nextLib, nextExe, nextSubLibs]
       nexts = G.overlays $ temp ^. each ^.. each . _1
       subsubs = temp ^. each ^.. each . _2 ^. each
-  return $
+  return
     ( currentLib
         <+> currentLibDeps
         <+> currentExe
@@ -183,10 +182,10 @@
   case cabal & condLibrary of
     Just lib -> do
       let name = getPkgName' cabal
-      trace' $ "Getting componential dependencies of " <> show name
+      trace' $ "Getting libs dependencies of " <> show name
       info <- evalConditionTree cabal lib
-      let libDeps = fmap unDepV $ buildDependsIfBuild info
-          toolDeps = fmap unExeV $ buildToolDependsIfBuild info
+      let libDeps = unDepV <$> buildDependsIfBuild info
+          toolDeps = unBuildTools $ buildToolsAndbuildToolDependsIfBuild info
       mapM_ (uncurry updateDependencyRecord) libDeps
       mapM_ (uncurry updateDependencyRecord) toolDeps
       let result = (fmap fst libDeps, fmap fst toolDeps)
@@ -197,18 +196,19 @@
 
 collectComponentialDeps ::
   (HasCallStack, Semigroup k, L.HasBuildInfo k, Members [FlagAssignmentsEnv, DependencyRecord, Trace] r) =>
+  String ->
   (GenericPackageDescription -> [(UnqualComponentName, CondTree ConfVar [Dependency] k)]) ->
   GenericPackageDescription ->
   [UnqualComponentName] ->
   Sem r (ComponentPkgList, ComponentPkgList)
-collectComponentialDeps f cabal skip = do
+collectComponentialDeps tag f cabal skip = do
   let conds = cabal & f
       name = getPkgName' cabal
-  trace' $ "Getting componential dependencies of " <> show name
+  trace' $ "Getting " <> tag <> " dependencies of " <> show name
   info <- filter (not . (`elem` skip) . fst) . zip (conds <&> fst) <$> mapM (evalConditionTree cabal . snd) conds
-  let deps = info <&> ((_2 %~) $ fmap unDepV . buildDependsIfBuild)
-      toolDeps = info <&> ((_2 %~) $ fmap unExeV . buildToolDependsIfBuild)
-      k = fmap (\(c, l) -> (c, fmap fst l))
+  let deps = info <&> _2 %~ (fmap unDepV . buildDependsIfBuild)
+      toolDeps = info <&> _2 %~ (unBuildTools . buildToolsAndbuildToolDependsIfBuild)
+      k = fmap (second $ fmap fst)
   mapM_ (uncurry updateDependencyRecord) $ deps ^.. each . _2 ^. each
   mapM_ (uncurry updateDependencyRecord) $ toolDeps ^.. each . _2 ^. each
   let result = (k deps, k toolDeps)
@@ -217,13 +217,13 @@
   return result
 
 collectExeDeps :: (HasCallStack, Members [FlagAssignmentsEnv, DependencyRecord, Trace] r) => GenericPackageDescription -> [UnqualComponentName] -> Sem r (ComponentPkgList, ComponentPkgList)
-collectExeDeps = collectComponentialDeps condExecutables
+collectExeDeps = collectComponentialDeps "exe" condExecutables
 
 collectTestDeps :: (HasCallStack, Members [FlagAssignmentsEnv, DependencyRecord, Trace] r) => GenericPackageDescription -> [UnqualComponentName] -> Sem r (ComponentPkgList, ComponentPkgList)
-collectTestDeps = collectComponentialDeps condTestSuites
+collectTestDeps = collectComponentialDeps "test" condTestSuites
 
 collectSubLibDeps :: (HasCallStack, Members [FlagAssignmentsEnv, DependencyRecord, Trace] r) => GenericPackageDescription -> [UnqualComponentName] -> Sem r (ComponentPkgList, ComponentPkgList)
-collectSubLibDeps = collectComponentialDeps condSubLibraries
+collectSubLibDeps = collectComponentialDeps "sublib" condSubLibraries
 
 updateDependencyRecord :: Member DependencyRecord r => PackageName -> VersionRange -> Sem r ()
 updateDependencyRecord name range = modify' $ Map.insertWith (<>) name [range]
@@ -234,17 +234,16 @@
 -----------------------------------------------------------------------------
 
 -- | Generate 'PkgBuild' for a 'SolvedPackage'.
-cabalToPkgBuild :: Members [HackageEnv, FlagAssignmentsEnv, WithMyErr] r => SolvedPackage -> PkgList -> Bool -> Sem r PkgBuild
-cabalToPkgBuild pkg ignored uusi = do
+cabalToPkgBuild :: Members [HackageEnv, FlagAssignmentsEnv, WithMyErr] r => SolvedPackage -> Bool -> Sem r PkgBuild
+cabalToPkgBuild pkg uusi = do
   let name = pkg ^. pkgName
-  cabal <- packageDescription <$> (getLatestCabal name)
-  _sha256sums <- (\case Just s -> "'" <> s <> "'"; Nothing -> "'SKIP'") <$> getLatestSHA256 name
+  cabal <- packageDescription <$> getLatestCabal name
+  _sha256sums <- (\case Just s -> "'" <> s <> "'"; Nothing -> "'SKIP'") <$> tryMaybe (getLatestSHA256 name)
   let _hkgName = pkg ^. pkgName & unPackageName
-      rawName = toLower <$> _hkgName
-      _pkgName = maybe rawName id $ stripPrefix "haskell-" rawName
+      _pkgName = unCommunityName . toCommunityName $ pkg ^. pkgName
       _pkgVer = prettyShow $ getPkgVersion cabal
       _pkgDesc = fromShortText $ synopsis cabal
-      getL (NONE) = ""
+      getL NONE = ""
       getL (License e) = getE e
       getE (ELicense (ELicenseId x) _) = show . mapLicense $ x
       getE (ELicense (ELicenseIdPlus x) _) = show . mapLicense $ x
@@ -253,19 +252,18 @@
       getE (EOr x y) = getE x <> " " <> getE y
 
       _license = getL . license $ cabal
-      _enableCheck = any id $ pkg ^. pkgDeps & mapped %~ (\dep -> selectDepKind Test dep && dep ^. depName == pkg ^. pkgName)
+      _enableCheck = or $ (pkg ^. pkgDeps) <&> depIsKind Test
       depends =
         pkg ^. pkgDeps
           ^.. each
             . filtered
               ( \x ->
-                  notMyself x
-                    && notInGHCLib x
-                    && ( selectDepKind Lib x
-                           || selectDepKind Exe x
-                           || selectDepKind SubLibs x
+                  depNotMyself name x
+                    && depNotInGHCLib x
+                    && ( depIsKind Lib x
+                           || depIsKind Exe x
+                           || depIsKind SubLibs x
                        )
-                    && notIgnore x
               )
       makeDepends =
         pkg ^. pkgDeps
@@ -273,24 +271,20 @@
             . filtered
               ( \x ->
                   x `notElem` depends
-                    && notMyself x
-                    && notInGHCLib x
-                    && ( selectDepKind LibBuildTools x
-                           || selectDepKind Test x
-                           || selectDepKind TestBuildTools x
-                           || selectDepKind SubLibsBuildTools x
+                    && depNotMyself name x
+                    && depNotInGHCLib x
+                    && ( depIsKind LibBuildTools x
+                           || depIsKind ExeBuildTools x
+                           || depIsKind Test x
+                           || depIsKind TestBuildTools x
+                           || depIsKind SubLibsBuildTools x
                        )
-                    && notIgnore x
               )
       depsToString deps = deps <&> (wrap . unCommunityName . toCommunityName . _depName) & mconcat
       _depends = depsToString depends
       _makeDepends = (if uusi then " 'uusi'" else "") <> depsToString makeDepends
       _url = getUrl cabal
       wrap s = " '" <> s <> "'"
-      notInGHCLib x = (x ^. depName) `notElem` ghcLibList
-      notMyself x = x ^. depName /= name
-      notIgnore x = x ^. depName `notElem` ignored
-      selectDepKind k x = k `elem` (x ^. depType & mapped %~ dependencyTypeToKind)
       _licenseFile = licenseFiles cabal ^? ix 0
       _enableUusi = uusi
   return PkgBuild {..}
diff --git a/src/Distribution/ArchHs/Exception.hs b/src/Distribution/ArchHs/Exception.hs
--- a/src/Distribution/ArchHs/Exception.hs
+++ b/src/Distribution/ArchHs/Exception.hs
@@ -15,6 +15,7 @@
     printHandledIOException,
     printAppResult,
     interceptHttpException,
+    tryMaybe,
   )
 where
 
@@ -38,10 +39,10 @@
   | NetworkException HttpException
 
 instance Show MyException where
-  show (PkgNotFound name) = "Unable to find [" <> (unPackageName $ toHackageName name) <> "] (hackage name) / [" <> (unCommunityName $ toCommunityName name) <> "] (community name)"
-  show (VersionNotFound name version) = "Unable to find [" <> (unPackageName $ toHackageName name) <> "] (hackage name) / [" <> (unCommunityName $ toCommunityName name) <> "] (community name)" <> " " <> prettyShow version
-  show (TargetExist name provider) = "Target [" <> unPackageName name <> "] has been provided by " <> show provider
-  show (CyclicExist c) = "Graph contains a cycle " <> (show $ fmap unPackageName c)
+  show (PkgNotFound name) = "Unable to find \"" <> unPackageName (toHackageName name) <> "\""
+  show (VersionNotFound name version) = "Unable to find \"" <> unPackageName (toHackageName name) <> "\" " <> prettyShow version
+  show (TargetExist name provider) = "Target \"" <> unPackageName name <> "\" has been provided by " <> show provider
+  show (CyclicExist c) = "Graph contains a cycle \"" <> show (fmap unPackageName c) <> "\""
   show (NetworkException (JsonHttpException s)) = "Failed to parse response " <> s
   show (NetworkException (VanillaHttpException e)) = show e
 
@@ -63,3 +64,10 @@
   case x of
     Left err -> throw $ NetworkException err
     Right x' -> return x'
+
+-- | Like 'try' but discard the concrete exception.
+tryMaybe :: Member WithMyErr r => Sem r a -> Sem r (Maybe a)
+tryMaybe m =
+  try @MyException m >>= \case
+    Left _ -> return Nothing
+    Right x -> return $ Just x
diff --git a/src/Distribution/ArchHs/Hackage.hs b/src/Distribution/ArchHs/Hackage.hs
--- a/src/Distribution/ArchHs/Hackage.hs
+++ b/src/Distribution/ArchHs/Hackage.hs
@@ -62,11 +62,11 @@
 
 -- | Insert a 'GenericPackageDescription' into 'HackageDB'.
 insertDB :: GenericPackageDescription -> HackageDB -> HackageDB
-insertDB cabal db = Map.insert name packageData db
+insertDB cabal = Map.insert name packageData
   where
     name = getPkgName $ packageDescription cabal
     version = getPkgVersion $ packageDescription cabal
-    versionData = VersionData cabal $ Map.empty
+    versionData = VersionData cabal Map.empty
     packageData = Map.singleton version versionData
 
 -- | Read and parse @.cabal@ file.
@@ -91,8 +91,8 @@
 getLatestCabal = withLatestVersion cabalFile
 
 -- | Get the latest SHA256 sum of the tarball .
-getLatestSHA256 :: Members [HackageEnv, WithMyErr] r => PackageName -> Sem r (Maybe String)
-getLatestSHA256 = withLatestVersion (\vdata -> tarballHashes vdata Map.!? "sha256")
+getLatestSHA256 :: Members [HackageEnv, WithMyErr] r => PackageName -> Sem r String
+getLatestSHA256 = withLatestVersion (\vdata -> tarballHashes vdata Map.! "sha256")
 
 -- | Get 'GenericPackageDescription' with a specific version.
 getCabal :: Members [HackageEnv, WithMyErr] r => PackageName -> Version -> Sem r GenericPackageDescription
diff --git a/src/Distribution/ArchHs/Name.hs b/src/Distribution/ArchHs/Name.hs
--- a/src/Distribution/ArchHs/Name.hs
+++ b/src/Distribution/ArchHs/Name.hs
@@ -168,4 +168,4 @@
 isHaskellPackage :: CommunityName -> Bool
 isHaskellPackage name =
   let rep = toCommunityRep name
-   in (rep `elem` communityListP || "haskell-" `isPrefixOf` (unMyName rep)) && rep `notElem` falseListP
+   in (rep `elem` communityListP || "haskell-" `isPrefixOf` unMyName rep) && rep `notElem` falseListP
diff --git a/src/Distribution/ArchHs/OptionReader.hs b/src/Distribution/ArchHs/OptionReader.hs
--- a/src/Distribution/ArchHs/OptionReader.hs
+++ b/src/Distribution/ArchHs/OptionReader.hs
@@ -20,24 +20,21 @@
 import qualified Data.Map.Strict as Map
 import Data.Void (Void)
 import Distribution.ArchHs.Internal.Prelude
-import Distribution.ArchHs.Utils
 import Options.Applicative
 import System.FilePath (takeExtension)
 import qualified Text.Megaparsec as M
 import qualified Text.Megaparsec.Char as M
 
 readFlag :: [(String, String, Bool)] -> Map.Map PackageName FlagAssignment
-readFlag [] = Map.empty
 readFlag list =
-  Map.fromList
-    . fmap (\l -> (mkPackageName . (^. _1) . head $ l, foldr (\(_, f, v) acc -> insertFlagAssignment (mkFlagName f) v acc) (mkFlagAssignment []) l))
-    . groupBy (\a b -> uncurry (==) (getTwo _1 a b))
-    $ list
+  Map.map toAssignment $
+    foldr (\(name, fname, fvalue) acc -> Map.insertWith (<>) (mkPackageName name) [(mkFlagName fname, fvalue)] acc) Map.empty list
+  where
+    toAssignment = foldr (\(fname, fvalue) acc -> insertFlagAssignment fname fvalue acc) (mkFlagAssignment [])
 
 -- | Read a set of package name with flag assignments.
 --
 -- >>> f ""
--- Right (fromList [])
 -- >>> f "package_name:flag_name:true"
 -- Right (fromList [(PackageName "package_name",fromList [(FlagName "flag_name",(1,True))])])
 -- >>> f "package_name:flag_name_1:true,package_name:flag_name_2:false"
@@ -97,7 +94,7 @@
       check = map (\e -> if takeExtension e == ".cabal" then (e, True) else (e, False)) split
       failed = map fst . filter (not . snd) $ check
       successful = map fst . filter snd $ check
-   in if failed /= [] then Left ("Unexpected file name: " <> intercalate ", " failed) else Right $ successful
+   in if failed /= [] then Left ("Unexpected file name: " <> intercalate ", " failed) else Right successful
 
 -- | Read a 'Version'
 -- This function calls 'simpleParsec'.
diff --git a/src/Distribution/ArchHs/PP.hs b/src/Distribution/ArchHs/PP.hs
--- a/src/Distribution/ArchHs/PP.hs
+++ b/src/Distribution/ArchHs/PP.hs
@@ -26,10 +26,14 @@
 prettySkip = C.formatWith [C.magenta] . intercalate ", "
 
 prettyFlagAssignments :: Map.Map PackageName FlagAssignment -> String
-prettyFlagAssignments m = mconcat $ fmap (fmap (\(n, a) -> C.formatWith [C.magenta] (unPackageName n) <> "\n" <> C.formatWith [C.indent 4] (prettyFlagAssignment a))) Map.toList m
+prettyFlagAssignments m =
+  mconcat $
+    fmap (fmap (\(n, a) -> C.formatWith [C.magenta] (unPackageName n) <> "\n" <> prettyFlagAssignment a)) Map.toList m
 
 prettyFlagAssignment :: FlagAssignment -> String
-prettyFlagAssignment m = mconcat $ fmap (\(n, v) -> "⚐ " <> C.formatWith [C.yellow] (unFlagName n) <> " : " <> C.formatWith [C.cyan] (show v) <> "\n") $ unFlagAssignment m
+prettyFlagAssignment m =
+  mconcat $
+    (\(n, v) -> "    ⚐ " <> C.formatWith [C.yellow] (unFlagName n) <> " : " <> C.formatWith [C.cyan] (show v) <> "\n") <$> unFlagAssignment m
 
 prettyDeps :: [PackageName] -> String
 prettyDeps =
@@ -38,10 +42,10 @@
     . zip [1 ..]
 
 prettyFlags :: [(PackageName, [Flag])] -> String
-prettyFlags = mconcat . fmap (\(name, flags) -> (C.formatWith [C.magenta] $ unPackageName name <> "\n") <> mconcat (fmap (C.formatWith [C.indent 4] . prettyFlag) flags))
+prettyFlags = mconcat . fmap (\(name, flags) -> C.formatWith [C.magenta] (unPackageName name <> "\n") <> mconcat (C.formatWith [C.indent 4] . prettyFlag <$> flags))
 
 prettyFlag :: Flag -> String
-prettyFlag f = "⚐ " <> C.formatWith [C.yellow] name <> ":\n" <> mconcat (fmap (C.formatWith [C.indent 6]) $ ["description:\n" <> desc, "default: " <> def <> "\n", "isManual: " <> manual <> "\n"])
+prettyFlag f = "⚐ " <> C.formatWith [C.yellow] name <> ":\n" <> mconcat (C.formatWith [C.indent 6] <$> ["description:\n" <> desc, "default: " <> def <> "\n", "isManual: " <> manual <> "\n"])
   where
     name = unFlagName . flagName $ f
     desc = unlines . fmap (C.formatWith [C.indent 8]) . lines $ flagDescription f
@@ -54,19 +58,18 @@
 prettySolvedPkg :: SolvedPackage -> [(String, String)]
 prettySolvedPkg SolvedPackage {..} =
   (C.formatWith [C.bold, C.yellow] (unPackageName _pkgName), C.formatWith [C.red] "    ✘") :
-  ( fmap
-      ( \(i :: Int, SolvedDependency {..}) ->
-          let prefix = if i == length _pkgDeps then " └─" else " ├─"
-           in case _depProvider of
-                (Just x) -> ((C.formatWith [C.green] $ (T.unpack prefix) <> unPackageName _depName <> " " <> show _depType), ((C.formatWith [C.green] "✔ ") <> (C.formatWith [C.cyan] $ "[" <> show x <> "]")))
-                _ -> (C.formatWith [C.bold, C.yellow] $ (T.unpack prefix) <> unPackageName _depName <> " " <> show _depType, C.formatWith [C.red] "    ✘")
-      )
-      (zip [1 ..] _pkgDeps)
-  )
-prettySolvedPkg ProvidedPackage {..} = [((C.formatWith [C.green] $ unPackageName _pkgName), ((C.formatWith [C.green] "✔ ") <> (C.formatWith [C.cyan] $ "[" <> show _pkgProvider <> "]")))]
+  fmap
+    ( \(i :: Int, SolvedDependency {..}) ->
+        let prefix = if i == length _pkgDeps then " └─" else " ├─"
+         in case _depProvider of
+              (Just x) -> (C.formatWith [C.green] $ T.unpack prefix <> unPackageName _depName <> " " <> show _depType, C.formatWith [C.green] "✔ " <> C.formatWith [C.cyan] (show x))
+              _ -> (C.formatWith [C.bold, C.yellow] $ T.unpack prefix <> unPackageName _depName <> " " <> show _depType, C.formatWith [C.red] "    ✘")
+    )
+    (zip [1 ..] _pkgDeps)
+prettySolvedPkg ProvidedPackage {..} = [(C.formatWith [C.green] (unPackageName _pkgName), C.formatWith [C.green] "✔ " <> C.formatWith [C.cyan] (show _pkgProvider))]
 
 con :: [(String, String)] -> String
 con l = mconcat complemented
   where
     maxL = maximum $ fmap (length . fst) l
-    complemented = fmap (\(x, y) -> (x <> (replicate (maxL - length x) ' ') <> y <> "\n")) l
+    complemented = (\(x, y) -> x <> replicate (maxL - length x) ' ' <> y <> "\n") <$> l
diff --git a/src/Distribution/ArchHs/PkgBuild.hs b/src/Distribution/ArchHs/PkgBuild.hs
--- a/src/Distribution/ArchHs/PkgBuild.hs
+++ b/src/Distribution/ArchHs/PkgBuild.hs
@@ -14,6 +14,7 @@
     mapLicense,
     applyTemplate,
     felixTemplate,
+    metaTemplate,
   )
 where
 
@@ -142,7 +143,7 @@
       (pack _makeDepends)
       (pack _sha256sums)
       ( case _licenseFile of
-          Just n -> "\n" <> (installLicense $ pack n)
+          Just n -> "\n" <> installLicense (pack n)
           _ -> "\n"
       )
       (if _enableUusi then "\n" <> uusi <> "\n\n" else "\n")
@@ -178,11 +179,11 @@
 felixTemplate :: Text -> Text -> Text -> Text -> Text -> Text -> Text -> Text -> Text -> Text -> Text -> Text -> Text
 felixTemplate hkgname pkgname pkgver pkgdesc url license depends makedepends sha256sums licenseF uusiF checkF =
   [text|
-  # This file was generated by arch-hs, please check it manually.
+  # This file was generated by https://github.com/berberman/arch-hs, please check it manually.
   # Maintainer: Your Name <youremail@domain.com>
 
   _hkgname=$hkgname
-  pkgname=haskell-$pkgname
+  pkgname=$pkgname
   pkgver=$pkgver
   pkgrel=1
   pkgdesc="$pkgdesc"
@@ -218,3 +219,21 @@
     runhaskell Setup copy --destdir="$$pkgdir"$licenseF
   }
 |]
+
+-- | A fixed template of a haskell meta package.
+metaTemplate :: Text -> Text -> Text -> Text -> Text
+metaTemplate url pkgname comment depends =
+  [text|
+  # This file was generated by https://github.com/berberman/arch-hs, please check it manually.
+  # This is a meta package, containing only dependencies of the target.
+  # Maintainer: Your Name <youremail@domain.com>
+
+  pkgname=haskell-$pkgname-meta
+  pkgver=1
+  pkgrel=1
+  pkgdesc="Dependencies of $pkgname"
+  url="$url"
+  arch=('x86_64')
+  $comment
+  depends=('ghc-libs'$depends)
+  |]
diff --git a/src/Distribution/ArchHs/Types.hs b/src/Distribution/ArchHs/Types.hs
--- a/src/Distribution/ArchHs/Types.hs
+++ b/src/Distribution/ArchHs/Types.hs
@@ -130,12 +130,12 @@
 
 -- | Provider of a dependency.
 data DependencyProvider = ByCommunity | ByAur
-  deriving stock (Eq, Generic)
+  deriving stock (Eq, Ord, Generic)
   deriving anyclass (NFData)
 
 instance Show DependencyProvider where
-  show ByCommunity = "community"
-  show ByAur = "aur"
+  show ByCommunity = "[community]"
+  show ByAur = "[aur]"
 
 -- | A solved dependency, holden by 'SolvedPackage'
 data SolvedDependency = SolvedDependency
@@ -146,7 +146,7 @@
     -- | Types of the dependency
     _depType :: [DependencyType]
   }
-  deriving stock (Show, Eq, Generic)
+  deriving stock (Show, Eq, Ord, Generic)
   deriving anyclass (NFData)
 
 -- | A solved package collected from dgraph. This data type is not designed to be recursively,
@@ -166,7 +166,7 @@
         -- | Package dependencies
         _pkgDeps :: [SolvedDependency]
       }
-  deriving stock (Show, Eq, Generic)
+  deriving stock (Show, Eq, Ord, Generic)
   deriving anyclass (NFData)
 
 makeLenses ''SolvedDependency
diff --git a/src/Distribution/ArchHs/Utils.hs b/src/Distribution/ArchHs/Utils.hs
--- a/src/Distribution/ArchHs/Utils.hs
+++ b/src/Distribution/ArchHs/Utils.hs
@@ -11,18 +11,25 @@
     dependencyTypeToKind,
     unExe,
     unExeV,
+    unLegacyExeV,
+    unBuildTools,
     unDepV,
     getUrl,
     getTwo,
     buildDependsIfBuild,
-    buildToolDependsIfBuild,
+    buildToolsAndbuildToolDependsIfBuild,
     traceCallStack,
     trace',
+    depNotInGHCLib,
+    depNotMyself,
+    depIsKind,
+    extractFromEVR,
   )
 where
 
 import Control.Monad ((<=<))
 import Distribution.ArchHs.Internal.Prelude
+import Distribution.ArchHs.Local (ghcLibList)
 import Distribution.ArchHs.Types
 import Distribution.PackageDescription (repoLocation)
 import Distribution.Types.BuildInfo (BuildInfo (..))
@@ -32,6 +39,7 @@
     depVerRange,
   )
 import Distribution.Types.ExeDependency (ExeDependency (..))
+import Distribution.Types.LegacyExeDependency
 import qualified Distribution.Types.PackageId as I
 import Distribution.Utils.ShortText (fromShortText)
 import GHC.Stack
@@ -47,6 +55,14 @@
 unExeV :: ExeDependency -> (PackageName, VersionRange)
 unExeV (ExeDependency name _ v) = (name, v)
 
+-- | Extract the package name and the version range from a 'LegacyExeDependency'.
+unLegacyExeV :: LegacyExeDependency -> (PackageName, VersionRange)
+unLegacyExeV (LegacyExeDependency name v) = (mkPackageName name, v)
+
+-- | Extract and join package names and version ranges of '[LegacyExeDependency]' and '[ExeDependency]'.
+unBuildTools :: ([LegacyExeDependency], [ExeDependency]) -> [(PackageName, VersionRange)]
+unBuildTools (l, e) = (unLegacyExeV <$> l) <> (unExeV <$> e)
+
 -- | Extract the 'PackageName' and 'VersionRange' of a 'Dependency'.
 unDepV :: Dependency -> (PackageName, VersionRange)
 unDepV dep = (depPkgName dep, depVerRange dep)
@@ -74,16 +90,16 @@
     fromJust _ = fail "Impossible."
     home = f . fromShortText . homepage $ cabal
     vcs = repoLocation <=< (^? ix 0) . sourceRepos $ cabal
-    fallback = Just $ "https://hackage.haskell.org/package/" <> (unPackageName $ getPkgName cabal)
+    fallback = Just $ "https://hackage.haskell.org/package/" <> unPackageName (getPkgName cabal)
 
 -- | Map 'DependencyType' with its data constructor tag 'DependencyKind'.
 dependencyTypeToKind :: DependencyType -> DependencyKind
 dependencyTypeToKind (CExe _) = Exe
 dependencyTypeToKind (CExeBuildTools _) = ExeBuildTools
-dependencyTypeToKind (CLib) = Lib
+dependencyTypeToKind CLib = Lib
 dependencyTypeToKind (CTest _) = Test
 dependencyTypeToKind (CBenchmark _) = Benchmark
-dependencyTypeToKind (CLibBuildTools) = LibBuildTools
+dependencyTypeToKind CLibBuildTools = LibBuildTools
 dependencyTypeToKind (CTestBuildTools _) = TestBuildTools
 dependencyTypeToKind (CBenchmarkBuildTools _) = BenchmarkBuildTools
 dependencyTypeToKind (CSubLibs _) = SubLibs
@@ -97,9 +113,10 @@
 buildDependsIfBuild :: BuildInfo -> [Dependency]
 buildDependsIfBuild info = if buildable info then targetBuildDepends info else []
 
--- | Same as 'buildToolDepends', but check if this is 'buildable'.
-buildToolDependsIfBuild :: BuildInfo -> [ExeDependency]
-buildToolDependsIfBuild info = if buildable info then buildToolDepends info else []
+-- | 'buildToolDepends' combined with 'buildTools', and check if this is 'buildable'.
+-- Actually, we should avoid accessing these two fields directly, in in favor of 'Distribution.Simple.BuildToolDepends.getAllToolDependencies'
+buildToolsAndbuildToolDependsIfBuild :: BuildInfo -> ([LegacyExeDependency], [ExeDependency])
+buildToolsAndbuildToolDependsIfBuild info = if buildable info then (buildTools info, buildToolDepends info) else ([], [])
 
 -- | Trace with prefix @[TRACE]@.
 trace' :: MemberWithError Trace r => String -> Sem r ()
@@ -111,3 +128,26 @@
   trace . prefix $ prettyCallStack callStack
   where
     prefix = unlines . fmap ("[TRACE]  " ++) . lines
+
+-- | 'SolvedDependency' @x@' is not provided by ghc.
+depNotInGHCLib :: SolvedDependency -> Bool
+depNotInGHCLib x = (x ^. depName) `notElem` ghcLibList
+
+-- | 'SolvedDependency' @x@'s name is not equal to @name@.
+depNotMyself :: PackageName -> SolvedDependency -> Bool
+depNotMyself name x = x ^. depName /= name
+
+-- | 'SolvedDependency' @x@' has 'DependencyKind' @k@.
+depIsKind :: DependencyKind -> SolvedDependency -> Bool
+depIsKind k x = k `elem` (x ^. depType <&> dependencyTypeToKind)
+
+-- | Extract package version from epoch-version-release.
+--
+-- >>> extractFromEVR "8.10.2-1"
+-- "8.10.2"
+-- >>> extractFromEVR "3:2.4.11-19"
+-- "2.4.11"
+extractFromEVR :: String -> CommunityVersion
+extractFromEVR evr =
+  let ev = head $ splitOn "-" evr
+   in if ':' `elem` ev then tail $ dropWhile (/= ':') ev else ev
diff --git a/submit/Main.hs b/submit/Main.hs
--- a/submit/Main.hs
+++ b/submit/Main.hs
@@ -1,9 +1,11 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
 
 module Main (main) where
 
 import qualified Colourista as C
+import Control.Monad (unless)
 import qualified Data.Text as T
 import Distribution.ArchHs.Community
 import Distribution.ArchHs.Exception
@@ -19,27 +21,35 @@
   do
     Options {..} <- runArgsParser
 
-    let useDefaultHackage = isInfixOf "YOUR_HACKAGE_MIRROR" $ optHackagePath
-        useDefaultCommunity = "/var/lib/pacman/sync/community.db" == optCommunityPath
-
+    let useDefaultHackage = "YOUR_HACKAGE_MIRROR" `isInfixOf` optHackagePath
     when useDefaultHackage $ C.skipMessage "You didn't pass -h, use hackage index file from default path."
+
+#ifndef ALPM
+    let useDefaultCommunity = "/var/lib/pacman/sync/community.db" == optCommunityPath
     when useDefaultCommunity $ C.skipMessage "You didn't pass -c, use community db file from default path."
+#endif
 
     token <- lookupEnv "HACKAGE_API_TOKEN"
 
-    when (token == Nothing) $ C.warningMessage "You didn't set HACKAGE_API_TOKEN, dry run only."
+    when (null token) $ C.warningMessage "You didn't set HACKAGE_API_TOKEN, dry run only."
 
     let hasOutput = not $ null optOutput
-    when (hasOutput) $ do
-      C.infoMessage $ "Output will be dumped to " <> (T.pack optOutput) <> "."
+    when hasOutput $ do
+      C.infoMessage $ "Output will be dumped to " <> T.pack optOutput <> "."
       exist <- doesFileExist optOutput
       when exist $
-        C.warningMessage $ "File " <> (T.pack optOutput) <> " already existed, overwrite it."
+        C.warningMessage $ "File " <> T.pack optOutput <> " already existed, overwrite it."
     C.infoMessage "Start running..."
-    when (not $ optUpload || hasOutput) $
+    unless (optUpload || hasOutput) $
       C.warningMessage "Run diff and check only."
 
+#ifdef ALPM
+    when optAlpm $ C.infoMessage "Using alpm."
+    community <- if optAlpm then loadCommunityFFI else loadProcessedCommunity defaultCommunityPath
+#else
     community <- loadProcessedCommunity $ if useDefaultCommunity then defaultCommunityPath else optCommunityPath
+#endif
+
     C.infoMessage "Loading community.db..."
 
     hackage <- loadHackageDB =<< if useDefaultHackage then lookupHackagePath else return optHackagePath
@@ -48,4 +58,4 @@
     runSubmit community hackage (submit token optOutput optUpload) & printAppResult
 
 runSubmit :: CommunityDB -> HackageDB -> Sem '[CommunityEnv, HackageEnv, WithMyErr, Embed IO, Final IO] a -> IO (Either MyException a)
-runSubmit community hackage = runFinal . embedToFinal . errorToIOFinal . (runReader hackage) . (runReader community)
+runSubmit community hackage = runFinal . embedToFinal . errorToIOFinal . runReader hackage . runReader community
diff --git a/submit/Submit.hs b/submit/Submit.hs
--- a/submit/Submit.hs
+++ b/submit/Submit.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE TypeApplications #-}
 
@@ -9,6 +10,7 @@
 where
 
 import qualified Colourista as C
+import Control.Monad (unless)
 import qualified Data.ByteString.Char8 as BS
 import qualified Data.Map.Strict as Map
 import Data.Maybe (catMaybes, fromJust)
@@ -28,7 +30,11 @@
 
 data Options = Options
   { optHackagePath :: FilePath,
+#ifndef ALPM
     optCommunityPath :: FilePath,
+#else
+    optAlpm :: Bool,
+#endif
     optOutput :: FilePath,
     optUpload :: Bool
   }
@@ -44,6 +50,7 @@
           <> showDefault
           <> value "~/.cabal/packages/YOUR_HACKAGE_MIRROR/01-index.tar | 00-index.tar"
       )
+#ifndef ALPM
     <*> strOption
       ( long "community"
           <> metavar "PATH"
@@ -52,6 +59,12 @@
           <> showDefault
           <> value "/var/lib/pacman/sync/community.db"
       )
+#else
+      <*> switch
+        ( long "alpm"
+            <> help "Use libalpm to parse community db"
+        )
+#endif
     <*> Options.Applicative.option
       str
       ( long "output"
@@ -90,8 +103,8 @@
 
 distroRecordParser :: M.Parsec Void String DistroRecord
 distroRecordParser =
-  (M.between (M.char '"') (M.char '"') (M.many $ M.noneOf (",\"\n" :: String)) `M.sepBy` (M.char ',')) >>= \case
-    (a : b : c : []) -> return (a, b, c)
+  (M.between (M.char '"') (M.char '"') (M.many $ M.noneOf (",\"\n" :: String)) `M.sepBy` M.char ',') >>= \case
+    [a, b, c] -> return (a, b, c)
     _ -> fail "Failed to parse record"
 
 parseDistroCSV :: String -> DistroCSV
@@ -102,6 +115,8 @@
 genCSV :: Member CommunityEnv r => Sem r DistroCSV
 genCSV = do
   db <- ask @CommunityDB
+
+  {-# HLINT ignore "Use <&>" #-}
   let communityPackages = Map.toList db
       fields =
         communityPackages
@@ -115,7 +130,7 @@
       prefix = "https://www.archlinux.org/packages/community/x86_64/"
       processField (communityName, (hackageName, version)) =
         let communityName' =
-              if (hackageName `elem` ghcLibList || hackageName == "ghc")
+              if hackageName `elem` ghcLibList || hackageName == "ghc"
                 then "ghc"
                 else unCommunityName communityName
          in (unPackageName hackageName, version, prefix <> communityName')
@@ -126,12 +141,12 @@
   csv <- genCSV
   let v = renderDistroCSV csv
   embed $
-    when (not . null $ output) $ do
+    unless (null output) $ do
       C.infoMessage $ "Write file: " <> T.pack output
       writeFile output v
   check csv
   interceptHttpException $
-    when (token /= Nothing && upload) $ do
+    when ((not . null) token && upload) $ do
       C.infoMessage "Uploading..."
       let api = https "hackage.haskell.org" /: "distro" /: "Arch" /: "packages"
           r =
@@ -139,13 +154,13 @@
               header "Authorization" (BS.pack $ "X-ApiKey " <> fromJust token) <> header "Content-Type" "text/csv"
       result <- runReq defaultHttpConfig r
       C.infoMessage $ "StatusCode: " <> (T.pack . show $ responseStatusCode result)
-      C.infoMessage $ "ResponseMessage: " <> (decodeUtf8 $ responseStatusMessage result)
+      C.infoMessage $ "ResponseMessage: " <> decodeUtf8 (responseStatusMessage result)
       C.infoMessage "ResponseBody:"
       putStrLn . BS.unpack $ responseBody result
 
 check :: Members [HackageEnv, WithMyErr, Embed IO] r => DistroCSV -> Sem r ()
 check community = do
-  embed $ C.infoMessage "Checking generated CSV file..."
+  embed $ C.infoMessage "Checking generated csv file..."
 
   let hackageNames = fmap (\(a, _, _) -> a) community
       pipe = fmap (\case Left (PkgNotFound x) -> Just (unCommunityName $ toCommunityName x); _ -> Nothing)
@@ -153,7 +168,7 @@
   failed <- catMaybes . pipe <$> mapM (\x -> try @MyException (getLatestCabal $ mkPackageName x)) hackageNames
 
   embed $
-    when (not $ null failed) $
+    unless (null failed) $
       C.warningMessage "Following packages in community are not linked to hackage:"
 
   embed . putStrLn . unlines $ failed
@@ -170,11 +185,11 @@
       ppRecord b (name, version, url) = (if b then C.formatWith [C.green] else C.formatWith [C.red]) $ "(" <> name <> ", " <> version <> ", " <> url <> ")"
 
   embed . putStrLn $ C.formatWith [C.magenta] "Diff:"
-  embed $ case (diffNew <> diffOld) of
+  embed $ case diffNew <> diffOld of
     [] -> putStrLn "[]"
     _ -> do
       putStr . unlines $ fmap (ppRecord False) diffOld
       putStrLn $ replicate 68 '-'
       putStr . unlines $ fmap (ppRecord True) diffNew
 
-  embed . putStrLn $ "Found " <> show (length hackage) <> " packages with submitted distribution information in hackage, and " <> show (length community) <> " haskell packages in community."
+  embed . putStrLn $ "Found " <> show (length hackage) <> " packages with submitted distribution information in hackage, and " <> show (length community) <> " haskell packages in [community]."