diff --git a/.github/workflows/packcheck.yml b/.github/workflows/packcheck.yml
index edd0157..cd321c3 100644
--- a/.github/workflows/packcheck.yml
+++ b/.github/workflows/packcheck.yml
@@ -149,8 +149,8 @@ jobs:
             command: cabal
             ghc_version: 9.14.1
             # WARNING! cannot use # comments inside pack_options.
-            #pack_options: >-
-            #  CABAL_PROJECT=cabal.project
+            pack_options: >-
+              CABAL_PROJECT=cabal.project.Werror
 
           - name: ci
             runner: macos-latest
diff --git a/.packcheck.ignore b/.packcheck.ignore
index 068de0c..b233951 100644
--- a/.packcheck.ignore
+++ b/.packcheck.ignore
@@ -1,6 +1,6 @@
 .packcheck.ignore
 .github/workflows/packcheck.yml
 .gitignore
-cabal.project.user
+cabal.project.Werror
 flake.lock
 flake.nix
diff --git a/README.md b/README.md
index f37a293..2c8d88a 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,39 @@
 packdiff diff <package-name> <rev1> <package-name> <rev2>
 ```
 
-**Limitations:**
+## API Diff Output
+
+```
+---------------------------------
+API Annotations
+---------------------------------
+
+[A] : Added
+[R] : Removed
+[C] : Changed
+[O] : Old definition
+[N] : New definition
+[D] : Deprecated
+
+---------------------------------
+API diff
+---------------------------------
+
+[C] Streamly.Data.Stream.Prelude
+    [A] useAcquire :: AcquireIO -> Config -> Config
+    [D] parEval :: MonadAsync m => (Config -> Config) -> Stream m a -> Stream m a
+[C] Streamly.Data.Fold.Prelude
+    [C] toHashMapIO
+        [O] toHashMapIO :: (MonadIO m, Hashable k, Ord k) => (a -> k) -> Fold m a b -> Fold m a (HashMap k b)
+        [N] toHashMapIO :: (MonadIO m, Hashable k) => (a -> k) -> Fold m a b -> Fold m a (HashMap k b)
+```
+
+## CI Integration
+
+For CI integration check out packdiff github CI in the streamly repo:
+https://github.com/composewell/streamly.
+
+## Limitations
 
 Packdiff uses the hoogle file created by haddock to generate and compare the
 difference between multiple versions of a package
diff --git a/cabal.project.Werror b/cabal.project.Werror
new file mode 100644
index 0000000..341ecff
--- /dev/null
+++ b/cabal.project.Werror
@@ -0,0 +1,4 @@
+packages: .
+
+package packdiff
+  ghc-options: -Werror
diff --git a/cabal.project.user b/cabal.project.user
deleted file mode 100644
index e6fdbad..0000000
--- a/cabal.project.user
+++ /dev/null
@@ -1 +0,0 @@
-packages: .
diff --git a/cli/Main.hs b/cli/Main.hs
index 76edc34..c3838dc 100644
--- a/cli/Main.hs
+++ b/cli/Main.hs
@@ -1,3 +1,11 @@
+-- |
+-- Module      : Main
+-- Copyright   : (c) 2022 Composewell Technologies
+-- License     : BSD-3-Clause
+-- Maintainer  : streamly@composewell.com
+-- Stability   : released
+-- Portability : GHC
+
 module Main
     ( main
     ) where
@@ -17,9 +25,10 @@ import System.Environment (getArgs)
 import qualified Data.Map as Map
 import qualified Streamly.Data.Fold as Fold
 import qualified Streamly.Data.Stream as Stream
-import qualified Streamly.Internal.FileSystem.File as File
+import qualified Streamly.Internal.FileSystem.FileIO as File
 import qualified Streamly.Internal.System.Command as Command
 import qualified Streamly.Internal.Unicode.Stream as Unicode
+import qualified Streamly.FileSystem.Path as Path
 
 import Diff
 import HoogleFileParser
@@ -67,7 +76,7 @@ checkoutAndGenerateHoogleFile target rev = do
 
 fileToLines :: String -> Stream IO String
 fileToLines path =
-    File.readChunks path & Unicode.decodeUtf8Chunks
+    File.readChunks (Path.fromString_ path) & Unicode.decodeUtf8Chunks
         & Stream.foldMany (Fold.takeEndBy_ (== '\n') Fold.toList)
 
 isDeprecated :: [Annotation] -> Bool
diff --git a/packdiff.cabal b/packdiff.cabal
index 2c39309..16c0ec2 100644
--- a/packdiff.cabal
+++ b/packdiff.cabal
@@ -1,19 +1,32 @@
 cabal-version:       2.2
--- Initial package description 'packdiff.cabal' generated by 'cabal
--- init'.  For further documentation, see
--- http://haskell.org/cabal/users-guide/
-
 name:                packdiff
 version:             0.1.0.0
--- synopsis:
--- description:
--- bug-reports:
+synopsis: Find API changes between different versions of a package
+description:
+  Packdiff compares different Git commits or Hackage versions of a package to
+  identify:
+  .
+  * Signature changes.
+  * Deprecated functions.
+  * Added or removed functions.
+  .
+  It helps you to:
+  .
+  * Generate API changelogs automatically.
+  * Generate API diff on pull requests.
+  * Compare new changes against published Hackage releases.
+  * Decide the new version of a package.
+  * Find breaking changes in the new release.
+  .
+  See the README for more details.
+  .
+bug-reports:         https://github.com/composewell/packdiff/issues
 license:             Apache-2.0
 license-file:        LICENSE
 author:              Composewell Technologies
 maintainer:          streamly@composewell.com
 copyright:           2022 Composewell Technologies
--- category:
+category: Development, Package Management, Cabal, PVP
 build-type:          Simple
 tested-with:
     GHC==9.14.1
@@ -23,6 +36,10 @@ tested-with:
   , GHC==9.6.3
 extra-doc-files:  README.md, CHANGELOG.md
 
+source-repository head
+    type: git
+    location: https://github.com/composewell/packdiff
+
 common compile-options
     default-language: Haskell2010
     ghc-options:  -Weverything
@@ -30,12 +47,15 @@ common compile-options
                   -Wno-implicit-prelude
                   -Wno-missing-import-lists
                   -Wno-missing-deriving-strategies
+                  -Wno-missing-kind-signatures
                   -Wno-missing-local-signatures
+                  -Wno-missing-role-annotations
                   -Wno-missing-safe-haskell-mode
                   -Wno-missed-specialisations
                   -Wno-monomorphism-restriction
                   -Wno-prepositive-qualified-module
                   -Wno-unsafe
+                  -Wno-x-partial
 
 library
   import: compile-options
diff --git a/src/Diff.hs b/src/Diff.hs
index b4e199a..d97f1c6 100644
--- a/src/Diff.hs
+++ b/src/Diff.hs
@@ -1,3 +1,11 @@
+-- |
+-- Module      : Diff
+-- Copyright   : (c) 2022 Composewell Technologies
+-- License     : BSD-3-Clause
+-- Maintainer  : streamly@composewell.com
+-- Stability   : released
+-- Portability : GHC
+
 module Diff
     ( StatusTag(..)
     , diffAPI
diff --git a/src/HoogleFileParser.hs b/src/HoogleFileParser.hs
index 63801b7..8f7a0ba 100644
--- a/src/HoogleFileParser.hs
+++ b/src/HoogleFileParser.hs
@@ -1,3 +1,10 @@
+-- |
+-- Module      : HoogleFileParser
+-- Copyright   : (c) 2022 Composewell Technologies
+-- License     : BSD-3-Clause
+-- Maintainer  : streamly@composewell.com
+-- Stability   : released
+-- Portability : GHC
 
 module HoogleFileParser
     ( -- Types
diff --git a/src/Pretty.hs b/src/Pretty.hs
index 666c5d5..dc90b7f 100644
--- a/src/Pretty.hs
+++ b/src/Pretty.hs
@@ -1,3 +1,10 @@
+-- |
+-- Module      : Pretty
+-- Copyright   : (c) 2022 Composewell Technologies
+-- License     : BSD-3-Clause
+-- Maintainer  : streamly@composewell.com
+-- Stability   : released
+-- Portability : GHC
 
 module Pretty
     ( prettyAPI
@@ -24,11 +31,13 @@ import Diff
 -- Printing helpers
 --------------------------------------------------------------------------------
 
+{-
 prettyTag :: StatusTag s -> String
 prettyTag Added = "[A]"
 prettyTag Removed = "[R]"
 prettyTag Same = "[S]"
 prettyTag (Changed _) = "[C]"
+-}
 
 isDeprecated :: [Annotation] -> Bool
 isDeprecated anns =
@@ -72,12 +81,13 @@ prettyD0_ _ (Tagged (Attach (DBoth annsL annsR) Same) b) =
     if isDeprecated annsR && not (isDeprecated annsL)
     then ["[D] " ++ showECT b]
     else [""]
+prettyD0_ _ _ = error "prettyD0_: impossible pattern"
 
 prettyD1_ ::
        String
     -> Tagged (Attach (Diff [Annotation]) (StatusTag ())) (Map String (Tagged (Attach (Diff [Annotation]) (StatusTag EntityContextType)) EntityContextType))
     -> [String]
-prettyD1_ k (Tagged (Attach (DLeft anns) Removed) b) =
+prettyD1_ k (Tagged (Attach (DLeft anns) Removed) _) =
     if isDeprecated anns
     then [""]
     else ["[R] " ++ k]
@@ -93,17 +103,18 @@ prettyD1_ k (Tagged (Attach (DBoth annsL annsR) (Changed ())) b) =
          else if not (isDeprecated annsR) && isDeprecated annsL
               then [""]
               else concat [["[C] " ++ k], indenter 4 (prettyD0 b)]
-prettyD1_ k (Tagged (Attach (DBoth annsL annsR) Same) b) =
+prettyD1_ k (Tagged (Attach (DBoth annsL annsR) Same) _) =
     if isDeprecated annsR && not (isDeprecated annsL)
     then ["[D] " ++ k]
     else [""]
+prettyD1_ _ _ = error "prettyD1_: impossible pattern"
 
 prettyAPI_ ::
        [Element]
     -> ModuleName
     -> Tagged (Attach (Diff [Annotation]) (StatusTag ())) (ModuleContextDefault (Attach (Diff [Annotation]) (StatusTag ())) (Attach (Diff [Annotation]) (StatusTag EntityContextType)))
     -> [String]
-prettyAPI_ _ k (Tagged (Attach (DLeft anns) Removed) b) =
+prettyAPI_ _ k (Tagged (Attach (DLeft anns) Removed) _) =
     if isDeprecated anns
     then [""]
     else ["[R] " ++ k]
@@ -119,10 +130,11 @@ prettyAPI_ elems k (Tagged (Attach (DBoth annsL annsR) (Changed ())) b) =
          else if not (isDeprecated annsR) && isDeprecated annsL
               then [""]
               else concat [["[C] " ++ k], indenter 4 (prettyMC elems b)]
-prettyAPI_ _ k (Tagged (Attach (DBoth annsL annsR) Same) b) =
+prettyAPI_ _ k (Tagged (Attach (DBoth annsL annsR) Same) _) =
     if isDeprecated annsR && not (isDeprecated annsL)
     then ["[D] " ++ k]
     else [""]
+prettyAPI_ _ _ _ = error "prettyAPI_: impossible pattern"
 
 indenter :: Int -> [String] -> [String]
 indenter i = map (replicate i ' ' ++)
@@ -156,7 +168,7 @@ prettyD1 ::
        Bool
     -> Map String (Tagged (Attach (Diff [Annotation]) (StatusTag ())) (Map String (Tagged (Attach (Diff [Annotation]) (StatusTag EntityContextType)) EntityContextType)))
     -> [String]
-prettyD1 l = SMap.foldlWithKey step initial
+prettyD1 _ = SMap.foldlWithKey step initial
 
     where