diff --git a/feedback/src/Feedback/Common/OptParse.hs b/feedback/src/Feedback/Common/OptParse.hs
index 242301a..b89ca6d 100644
--- a/feedback/src/Feedback/Common/OptParse.hs
+++ b/feedback/src/Feedback/Common/OptParse.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE DerivingVia #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedLists #-}
@@ -16,9 +15,7 @@ import qualified Data.Map as M
 import Data.Maybe
 import qualified Data.Text as T
 import Data.Version
-import Data.Yaml (FromJSON, ToJSON)
 import qualified Env
-import GHC.Generics (Generic)
 import Options.Applicative as OptParse
 import qualified Options.Applicative.Help as OptParse (pretty)
 import Path
@@ -31,7 +28,7 @@ data LoopSettings = LoopSettings
     loopSettingOutputSettings :: !OutputSettings,
     loopSettingHooksSettings :: !HooksSettings
   }
-  deriving (Show, Eq, Generic)
+  deriving (Show)
 
 combineToLoopSettings :: Flags -> Environment -> Maybe OutputConfiguration -> LoopConfiguration -> IO LoopSettings
 combineToLoopSettings Flags {..} Environment {} mDefaultOutputConfig LoopConfiguration {..} = do
@@ -48,7 +45,7 @@ data RunSettings = RunSettings
     runSettingExtraEnv :: !(Map String String),
     runSettingWorkingDir :: !(Maybe (Path Abs Dir))
   }
-  deriving (Show, Eq, Generic)
+  deriving (Show)
 
 combineToRunSettings :: RunConfiguration -> IO RunSettings
 combineToRunSettings RunConfiguration {..} = do
@@ -61,7 +58,7 @@ data FilterSettings = FilterSettings
   { filterSettingGitignore :: !Bool,
     filterSettingFind :: !(Maybe String)
   }
-  deriving (Show, Eq, Generic)
+  deriving (Show)
 
 combineToFilterSettings :: FilterConfiguration -> FilterSettings
 combineToFilterSettings FilterConfiguration {..} =
@@ -72,7 +69,7 @@ combineToFilterSettings FilterConfiguration {..} =
 data OutputSettings = OutputSettings
   { outputSettingClear :: !Clear
   }
-  deriving (Show, Eq, Generic)
+  deriving (Show)
 
 combineToOutputSettings :: OutputFlags -> OutputConfiguration -> OutputSettings
 combineToOutputSettings OutputFlags {..} mConf =
@@ -85,7 +82,7 @@ data HooksSettings = HooksSettings
   { hooksSettingBeforeAll :: Maybe RunSettings,
     hooksSettingAfterFirst :: Maybe RunSettings
   }
-  deriving (Show, Eq, Generic)
+  deriving (Show)
 
 combineToHooksSettings :: HooksConfiguration -> IO HooksSettings
 combineToHooksSettings HooksConfiguration {..} = do
@@ -97,8 +94,6 @@ data Configuration = Configuration
   { configLoops :: !(Map String LoopConfiguration),
     configOutputConfiguration :: !(Maybe OutputConfiguration)
   }
-  deriving stock (Show, Eq, Generic)
-  deriving (FromJSON, ToJSON) via (Autodocodec Configuration)
 
 instance HasCodec Configuration where
   codec =
@@ -123,8 +118,7 @@ data LoopConfiguration = LoopConfiguration
     loopConfigOutputConfiguration :: !OutputConfiguration,
     loopConfigHooksConfiguration :: !HooksConfiguration
   }
-  deriving stock (Show, Eq, Generic)
-  deriving (FromJSON, ToJSON) via (Autodocodec LoopConfiguration)
+  deriving (Eq)
 
 instance HasCodec LoopConfiguration where
   codec =
@@ -192,8 +186,7 @@ data RunConfiguration = RunConfiguration
     runConfigExtraEnv :: !(Map String String),
     runConfigWorkingDir :: !(Maybe FilePath)
   }
-  deriving stock (Show, Eq, Generic)
-  deriving (FromJSON, ToJSON) via (Autodocodec RunConfiguration)
+  deriving (Eq)
 
 instance HasCodec RunConfiguration where
   codec =
@@ -234,8 +227,7 @@ data FilterConfiguration = FilterConfiguration
   { filterConfigGitignore :: !(Maybe Bool),
     filterConfigFind :: !(Maybe String)
   }
-  deriving stock (Show, Eq, Generic)
-  deriving (FromJSON, ToJSON) via (Autodocodec FilterConfiguration)
+  deriving (Eq)
 
 instance HasCodec FilterConfiguration where
   codec =
@@ -269,8 +261,7 @@ emptyFilterConfiguration =
 data OutputConfiguration = OutputConfiguration
   { outputConfigClear :: !(Maybe Clear)
   }
-  deriving stock (Show, Eq, Generic)
-  deriving (FromJSON, ToJSON) via (Autodocodec OutputConfiguration)
+  deriving (Eq)
 
 instance HasCodec OutputConfiguration where
   codec =
@@ -299,7 +290,7 @@ data HooksConfiguration = HooksConfiguration
   { hooksConfigurationBeforeAll :: !(Maybe RunConfiguration),
     hooksConfigurationAfterFirst :: !(Maybe RunConfiguration)
   }
-  deriving (Show, Eq, Generic)
+  deriving (Eq)
 
 instance HasCodec HooksConfiguration where
   codec =
@@ -339,7 +330,6 @@ defaultConfigFile = do
 data Environment = Environment
   { envConfigFile :: !(Maybe FilePath)
   }
-  deriving (Show, Eq, Generic)
 
 getEnvironment :: IO Environment
 getEnvironment = Env.parse (Env.header "Environment") environmentParser
@@ -386,13 +376,11 @@ data Flags = Flags
     flagConfigFile :: !(Maybe FilePath),
     flagOutputFlags :: !OutputFlags
   }
-  deriving (Show, Eq, Generic)
 
 data OutputFlags = OutputFlags
   { outputFlagClear :: !(Maybe Clear),
     outputFlagDebug :: Bool
   }
-  deriving (Show, Eq, Generic)
 
 parseFlags :: OptParse.Parser Flags
 parseFlags =
@@ -440,7 +428,7 @@ parseOutputFlags =
       )
 
 newtype Command = CommandScript {unScript :: String}
-  deriving (Show, Eq, Generic)
+  deriving (Show, Eq)
 
 instance HasCodec Command where
   codec = dimapCodec CommandScript unScript codec
@@ -452,7 +440,7 @@ commandObjectCodec =
     (requiredField "command" "the command to run on change (alias for 'script' for backward compatibility)")
 
 data Clear = ClearScreen | DoNotClearScreen
-  deriving (Show, Eq, Generic)
+  deriving (Show, Eq)
 
 instance HasCodec Clear where
   codec = dimapCodec f g codec
diff --git a/feedback/src/Feedback/Common/Output.hs b/feedback/src/Feedback/Common/Output.hs
index a83c506..8652cde 100644
--- a/feedback/src/Feedback/Common/Output.hs
+++ b/feedback/src/Feedback/Common/Output.hs
@@ -37,9 +37,6 @@ indicatorChunk = fore cyan . chunk . T.pack . printf "%-12s"
 loopNameChunk :: String -> Chunk
 loopNameChunk = fore yellow . chunk . T.pack
 
-commandChunk :: String -> Chunk
-commandChunk = fore blue . chunk . T.pack
-
 startingLines :: RunSettings -> [[Chunk]]
 startingLines RunSettings {..} =
   let RunSettings _ _ _ = undefined
diff --git a/feedback/src/Feedback/Loop.hs b/feedback/src/Feedback/Loop.hs
index 1e6cf8b..98bae43 100644
--- a/feedback/src/Feedback/Loop.hs
+++ b/feedback/src/Feedback/Loop.hs
@@ -174,7 +174,6 @@ getTermCaps = pure WithoutColours
 data RestartEvent
   = FSEvent !FS.Event
   | StdinEvent !Char
-  deriving (Show, Eq)
 
 worker ::
   ThreadId ->
@@ -308,7 +307,6 @@ data Output
   | OutputKilled
   | OutputProcessStarted !RunSettings
   | OutputProcessExited !ExitCode !Word64
-  deriving (Show)
 
 putOutput :: OutputSettings -> TerminalCapabilities -> ZonedTime -> Output -> IO ()
 putOutput OutputSettings {..} terminalCapabilities loopBegin =
diff --git a/feedback/src/Feedback/Loop/Filter.hs b/feedback/src/Feedback/Loop/Filter.hs
index e796d9e..e5dd579 100644
--- a/feedback/src/Feedback/Loop/Filter.hs
+++ b/feedback/src/Feedback/Loop/Filter.hs
@@ -149,16 +149,6 @@ standardFilter here =
           ]
     }
 
-hidden :: Path Rel File -> Bool
-hidden = goFile
-  where
-    goFile :: Path Rel File -> Bool
-    goFile f = isHiddenIn (parent f) f || goDir (parent f)
-    goDir :: Path Rel Dir -> Bool
-    goDir f
-      | parent f == f = False
-      | otherwise = isHiddenIn (parent f) f || goDir (parent f)
-
 isHiddenIn :: Path b Dir -> Path b t -> Bool
 isHiddenIn curdir ad =
   case stripProperPrefix curdir ad of
diff --git a/feedback/src/Feedback/Test/OptParse.hs b/feedback/src/Feedback/Test/OptParse.hs
index efb0557..c7557fe 100644
--- a/feedback/src/Feedback/Test/OptParse.hs
+++ b/feedback/src/Feedback/Test/OptParse.hs
@@ -18,7 +18,7 @@ getSettings = do
 data TestSettings = TestSettings
   { testSettingLoops :: !(Map String LoopSettings)
   }
-  deriving (Show, Eq)
+  deriving (Show)
 
 combineToTestSettings :: Flags -> Environment -> Maybe Configuration -> IO TestSettings
 combineToTestSettings flags@Flags {..} environment mConf = do
diff --git a/flake.lock b/flake.lock
index 1fe0886..c8ffa08 100644
--- a/flake.lock
+++ b/flake.lock
@@ -182,7 +182,8 @@
         "pre-commit-hooks": "pre-commit-hooks",
         "safe-coloured-text": "safe-coloured-text",
         "sydtest": "sydtest",
-        "validity": "validity"
+        "validity": "validity",
+        "weeder-nix": "weeder-nix"
       }
     },
     "safe-coloured-text": {
@@ -247,6 +248,22 @@
         "repo": "validity",
         "type": "github"
       }
+    },
+    "weeder-nix": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1712652513,
+        "narHash": "sha256-etbllbKKJNVHogT89VkgevuaSLa0SA24OGpSDKTrGX0=",
+        "owner": "NorfairKing",
+        "repo": "weeder-nix",
+        "rev": "d49eebf716fd512d5e521bfed49c3281ca12dc1c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NorfairKing",
+        "repo": "weeder-nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index 496f209..3a11332 100644
--- a/flake.nix
+++ b/flake.nix
@@ -8,6 +8,8 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs?ref=nixos-23.11";
     pre-commit-hooks.url = "github:cachix/pre-commit-hooks.nix";
+    weeder-nix.url = "github:NorfairKing/weeder-nix";
+    weeder-nix.flake = false;
     validity.url = "github:NorfairKing/validity";
     validity.flake = false;
     autodocodec.url = "github:NorfairKing/autodocodec";
@@ -26,6 +28,7 @@
     { self
     , nixpkgs
     , pre-commit-hooks
+    , weeder-nix
     , validity
     , safe-coloured-text
     , sydtest
@@ -46,6 +49,7 @@
           (import (fast-myers-diff + "/nix/overlay.nix"))
           (import (validity + "/nix/overlay.nix"))
           (import (dekking + "/nix/overlay.nix"))
+          (import (weeder-nix + "/nix/overlay.nix"))
         ];
       };
       pkgs = pkgsFor nixpkgs;
@@ -66,6 +70,10 @@
           coverables = [ "feedback" ];
           coverage = [ "feedback-test-harness" ];
         };
+        weeder-check = pkgs.weeder-nix.makeWeederCheck {
+          weederToml = ./weeder.toml;
+          packages = [ "feedback" "feedback-test-harness" ];
+        };
         pre-commit = pre-commit-hooks.lib.${system}.run {
           src = ./.;
           hooks = {
diff --git a/weeder.toml b/weeder.toml
new file mode 100644
index 0000000..e689d0b
--- /dev/null
+++ b/weeder.toml
@@ -0,0 +1,9 @@
+unused-types = true
+type-class-roots = false
+roots = [
+  # General
+  ".main$",
+  "^Paths_.*",
+]
+root-instances = [
+]