diff --git a/src/Niv/Cli.hs b/src/Niv/Cli.hs
index c16ecf0..6fc37f7 100644
--- a/src/Niv/Cli.hs
+++ b/src/Niv/Cli.hs
@@ -55,8 +55,7 @@ li = liftIO
 cli :: IO ()
 cli = do
   ((fsj, colors), nio) <-
-    execParserPure' Opts.defaultPrefs opts <$> getArgs
-      >>= Opts.handleParseResult
+    getArgs >>= Opts.handleParseResult . execParserPure' Opts.defaultPrefs opts
   setColors colors
   runReaderT (runNIO nio) fsj
   where
@@ -471,8 +470,7 @@ cmdUpdate = \case
               Just "git" -> gitCmd
               Just "local" -> localCmd
               _ -> githubCmd
-        finalSpec <- fmap attrsToSpec <$> li (doUpdate initialSpec cmd)
-        pure finalSpec
+        fmap attrsToSpec <$> li (doUpdate initialSpec cmd)
     let (failed, sources') = partitionEithersHMS esources'
     unless (HMS.null failed) $
       li $
@@ -578,7 +576,7 @@ cmdDrop packageName = \case
     tsay $ "Dropping package: " <> unPackageName packageName
     fsj <- getFindSourcesJson
     sources <- unSources <$> li (getSources fsj)
-    when (not $ HMS.member packageName sources) $
+    unless (HMS.member packageName sources) $
       li $
         abortCannotDropNoSuchPackage packageName
     li $
diff --git a/src/Niv/Git/Cmd.hs b/src/Niv/Git/Cmd.hs
index 7a86eea..78a1444 100644
--- a/src/Niv/Git/Cmd.hs
+++ b/src/Niv/Git/Cmd.hs
@@ -15,6 +15,7 @@ import qualified Data.ByteString.Char8 as B8
 import qualified Data.HashMap.Strict as HMS
 import Data.Maybe
 import qualified Data.Text as T
+import Data.Char (isDigit)
 import Data.Text.Extended as T
 import Niv.Cmd
 import Niv.Logger
@@ -52,7 +53,7 @@ gitExtraLogs attrs = noteRef <> warnRefBranch <> warnRefTag
         mkWarn
           "Your source contains both a `ref` and a `tag`. The `ref` will be used by Nix to fetch the repo."
     member x = HMS.member x attrs
-    textIf cond txt = if cond then [txt] else []
+    textIf cond txt = [txt | cond]
 
 parseGitShortcut :: T.Text -> Maybe (PackageName, Aeson.Object)
 parseGitShortcut txt'@(T.dropWhileEnd (== '/') -> txt) =
@@ -179,7 +180,7 @@ latestRev repo branch = do
   sout <- runGit gitArgs
   case sout of
     ls@(_ : _ : _) -> abortTooMuchOutput gitArgs ls
-    (l1 : []) -> parseRev gitArgs l1
+    [l1] -> parseRev gitArgs l1
     [] -> abortNoOutput gitArgs
   where
     parseRev args l = maybe (abortNoRev args l) pure $ do
@@ -241,7 +242,7 @@ runGit args = do
 isRev :: T.Text -> Bool
 isRev t =
   -- commit hashes are comprised of abcdef0123456789
-  T.all (\c -> (c >= 'a' && c <= 'f') || (c >= '0' && c <= '9')) t
+  T.all (\c -> (c >= 'a' && c <= 'f') || isDigit c) t
     &&
     -- commit _should_ be 40 chars long, but to be sure we pick 7
     T.length t >= 7
diff --git a/src/Niv/Git/Test.hs b/src/Niv/Git/Test.hs
index 8a0f9d0..36f105e 100644
--- a/src/Niv/Git/Test.hs
+++ b/src/Niv/Git/Test.hs
@@ -59,7 +59,7 @@ test_gitUpdateRev :: IO ()
 test_gitUpdateRev = do
   interState <- evalUpdate initialState $ proc () ->
     gitUpdate (error "should be def") defaultBranchAndHEAD' -< ()
-  let interState' = HMS.map (first (\_ -> Free)) interState
+  let interState' = HMS.map (first (const Free)) interState
   actualState <- evalUpdate interState' $ proc () ->
     gitUpdate latestRev' (error "should update") -< ()
   unless ((snd <$> actualState) == expectedState) $
@@ -109,7 +109,7 @@ test_gitCalledOnce = do
   latestRev'' <- once2 latestRev'
   interState <- evalUpdate initialState $ proc () ->
     gitUpdate (error "should be def") defaultBranchAndHEAD'' -< ()
-  let interState' = HMS.map (first (\_ -> Free)) interState
+  let interState' = HMS.map (first (const Free)) interState
   actualState <- evalUpdate interState' $ proc () ->
     gitUpdate latestRev'' (error "should update") -< ()
   unless ((snd <$> actualState) == expectedState) $
diff --git a/src/Niv/GitHub.hs b/src/Niv/GitHub.hs
index fdb2918..2291e8a 100644
--- a/src/Niv/GitHub.hs
+++ b/src/Niv/GitHub.hs
@@ -35,14 +35,14 @@ githubUpdate prefetch latestRev ghRepo = proc () -> do
   let isTarGuess = (\u -> "tar.gz" `T.isSuffixOf` u || ".tgz" `T.isSuffixOf` u) <$> url
   type' <- useOrSet "type" -< bool "file" "tarball" <$> isTarGuess :: Box T.Text
   let doUnpack = (== "tarball") <$> type'
-  _sha256 <- update "sha256" <<< run (\(up, u) -> prefetch up u) -< (,) <$> doUnpack <*> url
+  _sha256 <- update "sha256" <<< run (uncurry prefetch) -< (,) <$> doUnpack <*> url
   returnA -< ()
   where
     completeSpec :: Update () (Box T.Text)
     completeSpec = proc () -> do
       owner <- load "owner" -< ()
       repo <- load "repo" -< ()
-      repoInfo <- run (\(a, b) -> ghRepo a b) -< (,) <$> owner <*> repo
+      repoInfo <- run (uncurry ghRepo) -< (,) <$> owner <*> repo
       branch <-
         useOrSet "branch" <<< arr (fmap $ fromMaybe "master")
           -<
diff --git a/src/Niv/GitHub/API.hs b/src/Niv/GitHub/API.hs
index c79f89e..18e6294 100644
--- a/src/Niv/GitHub/API.hs
+++ b/src/Niv/GitHub/API.hs
@@ -81,9 +81,8 @@ defaultRequest (map T.encodeUtf8 -> parts) = do
   let path = T.encodeUtf8 githubPath <> BS8.intercalate "/" parts
   mtoken <- lookupEnv' "GITHUB_TOKEN"
   pure
-    $ ( flip (maybe id) mtoken $ \token ->
-          HTTP.addRequestHeader "authorization" ("token " <> BS8.pack token)
-      )
+    $ maybe id (\token ->
+          HTTP.addRequestHeader "authorization" ("token " <> BS8.pack token)) mtoken
     $ HTTP.setRequestPath path
     $ HTTP.addRequestHeader "user-agent" "niv"
     $ HTTP.addRequestHeader "accept" "application/vnd.github.v3+json"
@@ -140,18 +139,21 @@ lookupEnv' vn =
     Nothing -> lookupEnv ("NIV_" <> vn)
 
 githubHost :: T.Text
+{-# NOINLINE githubHost #-}
 githubHost = unsafePerformIO $ do
   lookupEnv' "GITHUB_HOST" >>= \case
     Just (T.pack -> x) -> pure x
     Nothing -> pure "github.com"
 
 githubApiPort :: Int
+{-# NOINLINE githubApiPort #-}
 githubApiPort = unsafePerformIO $ do
   lookupEnv' "GITHUB_API_PORT" >>= \case
     Just (readMaybe -> Just x) -> pure x
     _ -> pure $ if githubSecure then 443 else 80
 
 githubApiHost :: T.Text
+{-# NOINLINE githubApiHost #-}
 githubApiHost = unsafePerformIO $ do
   lookupEnv' "GITHUB_API_HOST" >>= \case
     Just (T.pack -> x) -> pure x
@@ -162,6 +164,7 @@ githubApiHost = unsafePerformIO $ do
 -- https://github.com/nmattia/niv/issues/280
 
 githubSecure :: Bool
+{-# NOINLINE githubSecure #-}
 githubSecure = unsafePerformIO $ do
   lookupEnv "NIV_GITHUB_INSECURE" >>= \case
     Just "" -> pure True
@@ -169,6 +172,7 @@ githubSecure = unsafePerformIO $ do
     Nothing -> pure True
 
 githubPath :: T.Text
+{-# NOINLINE githubPath #-}
 githubPath = unsafePerformIO $ do
   lookupEnv "NIV_GITHUB_PATH" >>= \case
     Just (T.pack -> x) -> pure $ fromMaybe x (T.stripSuffix "/" x) <> "/"
diff --git a/src/Niv/GitHub/Cmd.hs b/src/Niv/GitHub/Cmd.hs
index 00bbe0a..7dfde16 100644
--- a/src/Niv/GitHub/Cmd.hs
+++ b/src/Niv/GitHub/Cmd.hs
@@ -96,9 +96,7 @@ parseGitHubPackageSpec =
     -- Shortcuts for common attributes
     shortcutAttributes :: Opts.Parser (K.Key, Aeson.Value)
     shortcutAttributes =
-      foldr (<|>) empty $
-        mkShortcutAttribute
-          <$> ["branch", "owner", "rev", "version"]
+      foldr ((<|>) . mkShortcutAttribute) empty ["branch", "owner", "rev", "version"]
     -- TODO: infer those shortcuts from 'Update' keys
     mkShortcutAttribute :: T.Text -> Opts.Parser (K.Key, Aeson.Value)
     mkShortcutAttribute = \case
@@ -165,7 +163,7 @@ nixPrefetchURL unpack turl@(T.unpack -> url) = do
     (ExitSuccess, l : _) -> pure $ T.pack l
     _ -> abortNixPrefetchExpectedOutput (T.pack <$> args) (T.pack sout) (T.pack serr)
   where
-    args = (if unpack then ["--unpack"] else []) <> [url, "--name", sanitizeName basename]
+    args = (["--unpack" | unpack]) <> [url, "--name", sanitizeName basename]
     runNixPrefetch = readProcessWithExitCode "nix-prefetch-url" args ""
     sanitizeName = T.unpack . T.filter isOk
     basename = last $ T.splitOn "/" turl
@@ -173,7 +171,7 @@ nixPrefetchURL unpack turl@(T.unpack -> url) = do
     --  Path names are alphanumeric and can include the symbols +-._?= and must
     --  not begin with a period.
     -- (note: we assume they don't begin with a period)
-    isOk = \c -> isAlphaNum c || T.any (c ==) "+-._?="
+    isOk c = isAlphaNum c || T.any (c ==) "+-._?="
 
 abortNixPrefetchExpectedOutput :: [T.Text] -> T.Text -> T.Text -> IO a
 abortNixPrefetchExpectedOutput args sout serr =
diff --git a/src/Niv/GitHub/Test.hs b/src/Niv/GitHub/Test.hs
index 438ef3c..fa65876 100644
--- a/src/Niv/GitHub/Test.hs
+++ b/src/Niv/GitHub/Test.hs
@@ -165,7 +165,7 @@ test_githubUpdatesOnce = do
     error $
       "State mismatch: " <> show tmpState
   -- Set everything free
-  let tmpState' = HMS.map (first (\_ -> Free)) tmpState
+  let tmpState' = HMS.map (first (const Free)) tmpState
   actualState <- evalUpdate tmpState' $ proc () ->
     githubUpdate (prefetch ioref) latestRev ghRepo -< ()
   unless ((snd <$> actualState) == expectedState) $
diff --git a/src/Niv/Logger.hs b/src/Niv/Logger.hs
index 97f23be..883570c 100644
--- a/src/Niv/Logger.hs
+++ b/src/Niv/Logger.hs
@@ -55,7 +55,8 @@ setColors :: Colors -> IO ()
 setColors = writeIORef colors
 
 useColors :: Bool
-useColors = unsafePerformIO $ (\c -> c == Always) <$> readIORef colors
+{-# NOINLINE useColors #-}
+useColors = unsafePerformIO $ (== Always) <$> readIORef colors
 
 type S = String -> String
 
@@ -83,6 +84,7 @@ jobStackSize :: (MonadIO io) => io Int
 jobStackSize = readIORef jobStack
 
 jobStack :: IORef Int
+{-# NOINLINE jobStack #-}
 jobStack = unsafePerformIO $ newIORef 0
 
 {-# NOINLINE jobStackSize #-}
diff --git a/src/Niv/Sources.hs b/src/Niv/Sources.hs
index ac7b453..afe8690 100644
--- a/src/Niv/Sources.hs
+++ b/src/Niv/Sources.hs
@@ -62,13 +62,12 @@ getSourcesEither fsj = do
     valueToSources :: Aeson.Value -> Maybe Sources
     valueToSources = \case
       Aeson.Object obj ->
-        fmap (Sources . mapKeys PackageName . KM.toHashMapText) $
-          traverse
+        (Sources . mapKeys PackageName . KM.toHashMapText <$> traverse
             ( \case
                 Aeson.Object obj' -> Just (PackageSpec obj')
                 _ -> Nothing
             )
-            obj
+            obj)
       _ -> Nothing
     mapKeys :: (Eq k2, Hashable k2) => (k1 -> k2) -> HMS.HashMap k1 v -> HMS.HashMap k2 v
     mapKeys f = HMS.fromList . map (first f) . HMS.toList
@@ -86,7 +85,7 @@ getSources fsj = do
       pure
 
 setSources :: FindSourcesJson -> Sources -> IO ()
-setSources fsj sources = Aeson.encodeFilePretty (pathNixSourcesJson fsj) sources
+setSources fsj = Aeson.encodeFilePretty (pathNixSourcesJson fsj)
 
 newtype PackageName = PackageName {unPackageName :: T.Text}
   deriving newtype (Eq, Hashable, FromJSONKey, ToJSONKey, Show)
diff --git a/src/Niv/Update.hs b/src/Niv/Update.hs
index b8d2ed4..2bcddbf 100644
--- a/src/Niv/Update.hs
+++ b/src/Niv/Update.hs
@@ -276,7 +276,7 @@ runUpdate' attrs = \case
       v' <- runBox v
       case renderTemplate
         ( \k ->
-            (decodeBox $ "When rendering template " <> v') . snd
+            decodeBox ("When rendering template " <> v') . snd
               <$> HMS.lookup k attrs
         )
         v' of