diff --git a/package.yaml b/package.yaml
index 820a16e46..0820ca9d3 100644
--- a/package.yaml
+++ b/package.yaml
@@ -156,24 +156,35 @@ default-extensions:
   - BinaryLiterals
   - PolyKinds
 
-ghc-options:
-  - -Wall
-  - -fwarn-tabs
+when:
+  - condition: flag(pedantic)
+    then:
+      ghc-options:
+        - -Wall
+        - -Werror
+        - -fwarn-tabs
+        - -fno-warn-type-defaults
+        - -fno-warn-partial-type-signatures
+    else:
+      ghc-options:
+        - -Wall
+        - -fno-warn-type-defaults
+        - -fno-warn-partial-type-signatures
 
 # The library contains all of our application code. The executable
 # defined below is just a thin wrapper.
 library:
   source-dirs: src
   when:
-  - condition: (flag(dev)) || (flag(library-only))
-    then:
-      ghc-options:
-        - -O0
-        - -ddump-splices
-      cpp-options: -DDEVELOPMENT
-    else:
-      ghc-options:
-        - -O2
+    - condition: (flag(dev)) || (flag(library-only))
+      then:
+        ghc-options:
+          - -O0
+          - -ddump-splices
+        cpp-options: -DDEVELOPMENT
+      else:
+        ghc-options:
+          - -O2
 
 # Runnable executable for our application
 executables:
@@ -219,3 +230,7 @@ flags:
     description: Turn on development settings, like auto-reload templates.
     manual: false
     default: false
+  pedantic:
+    description: Be very pedantic about warnings and errors
+    manual: true
+    default: true
diff --git a/routes b/routes
index 17a653125..f953da2e5 100644
--- a/routes
+++ b/routes
@@ -50,8 +50,8 @@
 !/term/#TermId             TermCourseListR   GET             !free
 !/term/#TermId/#SchoolId   TermSchoolCourseListR  GET             !free
 
-/school                    SchoolListR       GET
-/school/#SchoolId          SchoolShowR       GET
+/school                    SchoolListR       GET             !development
+/school/#SchoolId          SchoolShowR       GET             !development
 
 
 -- For Pattern Synonyms see Foundation
@@ -64,7 +64,7 @@
   /edit                       CEditR          GET POST
   /delete                     CDeleteR        GET POST        !lecturerANDempty
   /users                      CUsersR         GET
-  /user/#CryptoUUIDUser       CUserR          GET
+  /user/#CryptoUUIDUser       CUserR          GET             !development
   /correctors                 CHiWisR         GET
   /subs                       CCorrectionsR   GET POST
   /ex                         SheetListR      GET             !registered !materials
diff --git a/src/Cron.hs b/src/Cron.hs
index cb2d9a338..600eb873c 100644
--- a/src/Cron.hs
+++ b/src/Cron.hs
@@ -1,5 +1,6 @@
 module Cron
-  ( CronNextMatch(..)
+  ( evalCronMatch
+  , CronNextMatch(..)
   , nextCronMatch
   , module Cron.Types
   ) where
@@ -18,11 +19,7 @@ import Data.Ratio ((%))
 
 import qualified Data.Set as Set
 
-import Data.List.NonEmpty (NonEmpty(..))
-import qualified Data.List.NonEmpty as NonEmpty
-
-import Utils.Lens.TH
-import Control.Lens
+import Utils.Lens hiding (from, to)
 
   
 data CronDate = CronDate
@@ -38,7 +35,7 @@ makeLenses_ ''CronDate
 evalCronMatch :: CronMatch -> Natural -> Bool
 evalCronMatch CronMatchAny _ = True
 evalCronMatch CronMatchNone _ = False
-evalCronMatch (CronMatchSome set) x = Set.member x $ toNullable set
+evalCronMatch (CronMatchSome xs) x = Set.member x $ toNullable xs
 evalCronMatch (CronMatchStep step) x = (x `mod` step) == 0
 evalCronMatch (CronMatchContiguous from to) x = from <= x && x <= to
 evalCronMatch (CronMatchIntersect a b) x = evalCronMatch a x && evalCronMatch b x
@@ -115,7 +112,7 @@ genMatch :: Int -- ^ Period
          -> [Natural]
 genMatch p m st CronMatchAny = take p $ map (bool id (succ . (`mod` fromIntegral p)) m) [st..]
 genMatch _ _ _ CronMatchNone = []
-genMatch p m _ (CronMatchSome set) = take p . map (bool id (succ . (`mod` fromIntegral p)) m) . Set.toAscList $ toNullable set
+genMatch p m _ (CronMatchSome xs) = take p . map (bool id (succ . (`mod` fromIntegral p)) m) . Set.toAscList $ toNullable xs
 genMatch p m st (CronMatchStep step) = do
   start <- [st..st + step]
   guard $ (start `mod` step) == 0
@@ -135,9 +132,9 @@ genMatch p m st (CronMatchIntersect aGen bGen)
     mergeAnd [] _ = []
     mergeAnd _ [] = []
     mergeAnd (a:as) (b:bs)
-      | a <  b = mergeAnd as (b:bs)
-      | a == b = a : mergeAnd as bs
-      | a >  b = mergeAnd (a:as) bs
+      | a <  b    = mergeAnd as (b:bs)
+      | a == b    = a : mergeAnd as bs
+      | otherwise = mergeAnd (a:as) bs
 genMatch p m st (CronMatchUnion CronMatchNone other) = genMatch p m st other
 genMatch p m st (CronMatchUnion other CronMatchNone) = genMatch p m st other
 genMatch p m st (CronMatchUnion CronMatchAny _) = genMatch p m st CronMatchAny
@@ -147,9 +144,9 @@ genMatch p m st (CronMatchUnion aGen bGen) = merge (genMatch p m st aGen) (genMa
     merge [] bs = bs
     merge as [] = as
     merge (a:as) (b:bs)
-      | a <  b = a : merge as (b:bs)
-      | a == b = a : merge as bs
-      | a >  b = b : merge (a:as) bs
+      | a <  b    = a : merge as (b:bs)
+      | a == b    = a : merge as bs
+      | otherwise = b : merge (a:as) bs
 
 nextCronMatch :: TZ -- ^ Timezone of the `Cron`-Entry
               -> Maybe UTCTime -- ^ Time of last execution of the job
@@ -166,7 +163,6 @@ nextCronMatch tz mPrev now c@Cron{..} = case notAfter of
     | otherwise -> MatchNone
   MatchNone -> nextMatch
   where
-    nextMatch = nextCronMatch' tz mPrev now c
     notAfter
       | Right c' <- cronNotAfter
       , Just ref <- notAfterRef
@@ -178,34 +174,34 @@ nextCronMatch tz mPrev now c@Cron{..} = case notAfter of
     notAfterRef
       | Just prevT <- mPrev = Just prevT
       | otherwise = case execRef' now False cronInitial of
+          MatchAsap -> error "execRef' should not return MatchAsap"
           MatchAt t -> Just t
           MatchNone -> Nothing
-    
-    nextCronMatch' tz mPrev now c@Cron{..}
-      | isNothing mPrev
-      = execRef now False cronInitial
-      | Just prevT <- mPrev
-      = case cronRepeat of
-          CronRepeatOnChange
-            | not $ matchesCron tz Nothing prevT c
-              -> let
-                   cutoffTime = addUTCTime cronRateLimit prevT
-                 in case execRef now False cronInitial of
-                      MatchAsap
-                        | now < cutoffTime -> MatchAt cutoffTime
-                      MatchAt ts 
-                        | ts < cutoffTime -> MatchAt cutoffTime
-                      other -> other
-          CronRepeatScheduled cronNext
-            -> case cronNext of
-                 CronAsap
-                   | addUTCTime cronRateLimit prevT <= now
-                     -> MatchAsap
-                   | otherwise
-                     -> MatchAt $ addUTCTime cronRateLimit prevT
-                 cronNext
-                   -> execRef (addUTCTime cronRateLimit prevT) True cronNext
-          _other -> MatchNone
+    nextMatch = case mPrev of
+      Nothing
+        -> execRef now False cronInitial
+      Just prevT
+        -> case cronRepeat of
+            CronRepeatOnChange
+              | not $ matchesCron tz Nothing prevT c
+                -> let
+                     cutoffTime = addUTCTime cronRateLimit prevT
+                   in case execRef now False cronInitial of
+                        MatchAsap
+                          | now < cutoffTime -> MatchAt cutoffTime
+                        MatchAt ts 
+                          | ts < cutoffTime -> MatchAt cutoffTime
+                        other -> other
+            CronRepeatScheduled cronNext
+              -> case cronNext of
+                   CronAsap
+                     | addUTCTime cronRateLimit prevT <= now
+                       -> MatchAsap
+                     | otherwise
+                       -> MatchAt $ addUTCTime cronRateLimit prevT
+                   _other
+                     -> execRef (addUTCTime cronRateLimit prevT) True cronNext
+            _other -> MatchNone
 
     execRef ref wasExecd cronAbsolute = case execRef' ref wasExecd cronAbsolute of
       MatchAt t
@@ -219,19 +215,26 @@ nextCronMatch tz mPrev now c@Cron{..} = case notAfter of
         | otherwise -> MatchNone
       CronCalendar{..} -> listToMatch $ do
         let CronDate{..} = toCronDate $ utcToLocalTimeTZ tz ref
-        cronYear <- genMatch 400 False cdYear cronYear
-        cronWeekOfYear <- genMatch 53 True cdWeekOfYear cronWeekOfYear
-        cronDayOfYear <- genMatch 366 True cdDayOfYear cronDayOfYear
-        cronMonth <- genMatch 12 True cdMonth cronMonth
-        cronWeekOfMonth <- genMatch 5 True cdWeekOfMonth cronWeekOfMonth
-        cronDayOfMonth <- genMatch 31 True cdDayOfMonth cronDayOfMonth
-        cronDayOfWeek <- genMatch 7 True cdDayOfWeek cronDayOfWeek
-        cronHour <- genMatch 24 True cdHour cronHour
-        cronMinute <- genMatch 60 True cdMinute cronMinute
-        cronSecond <- genMatch 60 True cdSecond cronSecond
-        guard $ consistentCronDate CronDate{..}
-        localDay <- maybeToList $ fromGregorianValid (fromIntegral cronYear) (fromIntegral cronMonth) (fromIntegral cronDayOfMonth)
-        let localTimeOfDay = TimeOfDay (fromIntegral cronHour) (fromIntegral cronMinute) (fromIntegral cronSecond)
+
+        mCronYear <- genMatch 400 False cdYear cronYear
+        mCronWeekOfYear <- genMatch 53 True cdWeekOfYear cronWeekOfYear
+        mCronDayOfYear <- genMatch 366 True cdDayOfYear cronDayOfYear
+        mCronMonth <- genMatch 12 True cdMonth cronMonth
+        mCronWeekOfMonth <- genMatch 5 True cdWeekOfMonth cronWeekOfMonth
+        mCronDayOfMonth <- genMatch 31 True cdDayOfMonth cronDayOfMonth
+        mCronDayOfWeek <- genMatch 7 True cdDayOfWeek cronDayOfWeek
+        mCronHour <- genMatch 24 True cdHour cronHour
+        mCronMinute <- genMatch 60 True cdMinute cronMinute
+        mCronSecond <- genMatch 60 True cdSecond cronSecond
+        guard $ consistentCronDate CronDate
+          { cdYear = mCronYear, cdMonth = mCronMonth, cdDayOfMonth = mCronDayOfMonth
+          , cdHour = mCronHour, cdMinute = mCronMinute, cdSecond = mCronSecond
+          , cdWeekOfYear = mCronWeekOfYear, cdWeekOfMonth = mCronWeekOfMonth
+          , cdDayOfYear = mCronDayOfYear, cdDayOfWeek = mCronDayOfWeek
+          }
+
+        localDay <- maybeToList $ fromGregorianValid (fromIntegral mCronYear) (fromIntegral mCronMonth) (fromIntegral mCronDayOfMonth)
+        let localTimeOfDay = TimeOfDay (fromIntegral mCronHour) (fromIntegral mCronMinute) (fromIntegral mCronSecond)
         return $ localTimeToUTCTZ tz LocalTime{..}
       CronNotScheduled -> MatchNone
 
diff --git a/src/Foundation.hs b/src/Foundation.hs
index 4cb048b8d..ca40aa24a 100644
--- a/src/Foundation.hs
+++ b/src/Foundation.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE UndecidableInstances #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-} -- MonadCrypto
 
 module Foundation where
 
@@ -10,20 +11,18 @@ import Text.Jasmine         (minifym)
 import qualified Web.ClientSession as ClientSession
 
 import Yesod.Auth.Message
-import Yesod.Auth.Dummy
 import Auth.LDAP
 import Auth.PWHash
 import Auth.Dummy
 import Jobs.Types
 
-import qualified Network.Wai as W (requestMethod, pathInfo)
+import qualified Network.Wai as W (pathInfo)
 
 import Yesod.Default.Util   (addStaticContentExternal)
 import Yesod.Core.Types     (Logger)
 import qualified Yesod.Core.Unsafe as Unsafe
 import Data.CaseInsensitive (CI)
 import qualified Data.CaseInsensitive as CI
-import qualified Data.Text.Encoding as TE
 
 import qualified Data.CryptoID as E
 
@@ -40,12 +39,10 @@ import qualified Data.Text as Text
 import qualified Data.Text.Encoding as Text
 
 import Data.List (foldr1)
-import qualified Data.List as List
 import Data.Set (Set)
 import qualified Data.Set as Set
 import Data.Map (Map, (!?))
 import qualified Data.Map as Map
-import Data.List (findIndex)
 
 import Data.Monoid (Any(..))
 
@@ -61,22 +58,14 @@ import Control.Monad.Trans.Maybe (MaybeT(..))
 import Control.Monad.Trans.Reader (runReader, mapReaderT)
 import Control.Monad.Trans.Writer (WriterT(..))
 import Control.Monad.Writer.Class (MonadWriter(..))
-import Control.Monad.Catch (handleAll)
 import qualified Control.Monad.Catch as C
 
-import System.FilePath
-
-import Handler.Utils.Templates
 import Handler.Utils.StudyFeatures
 import Control.Lens
-import Utils
 import Utils.Form
-import Utils.Lens
 import Utils.SystemMessage
 
 import Data.Aeson hiding (Error, Success)
-import Data.Aeson.TH
-import qualified Data.Yaml as Yaml
 
 import Text.Shakespeare.Text (st)
 
@@ -147,9 +136,11 @@ type MsgRenderer = MsgRendererS UniWorX -- see Utils
 type MailM a = MailT (HandlerT UniWorX IO) a
 
 -- Pattern Synonyms for convenience
+pattern CSheetR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> SheetR -> Route UniWorX
 pattern CSheetR tid ssh csh shn ptn
   = CourseR tid ssh csh (SheetR shn ptn)
 
+pattern CSubmissionR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> CryptoFileNameSubmission -> SubmissionR -> Route UniWorX
 pattern CSubmissionR tid ssh csh shn cid ptn
   = CSheetR tid ssh csh shn (SubmissionR cid ptn)
 
@@ -212,9 +203,10 @@ instance RenderMessage UniWorX Load where
 newtype MsgLanguage = MsgLanguage Lang
   deriving (Eq, Ord, Show, Read)
 instance RenderMessage UniWorX MsgLanguage where
-  renderMessage foundation ls (MsgLanguage lang)
-    | lang == "de-DE" = mr MsgGermanGermany
-    | "de" `isPrefixOf` lang = mr MsgGerman
+  renderMessage foundation ls (MsgLanguage lang@(Text.splitOn "-" -> lang'))
+    | ["de", "DE"] <- lang' = mr MsgGermanGermany
+    | ("de" : _)   <- lang' = mr MsgGerman
+    | otherwise = lang
     where
       mr = renderMessage foundation ls
 
@@ -280,8 +272,8 @@ orAR  _  _ AuthenticationRequired  = AuthenticationRequired
 orAR  mr (Unauthorized x) (Unauthorized y) = Unauthorized . render mr $  MsgUnauthorizedOr x y
 -- and
 andAR mr (Unauthorized x) (Unauthorized y) = Unauthorized . render mr $  MsgUnauthorizedAnd x y
-andAR _  reason@(Unauthorized x) _ = reason
-andAR _  _ reason@(Unauthorized x) = reason
+andAR _  reason@(Unauthorized _) _ = reason
+andAR _  _ reason@(Unauthorized _) = reason
 andAR _  Authorized          other = other
 andAR _  AuthenticationRequired  _ = AuthenticationRequired
 
@@ -338,6 +330,14 @@ knownTags = Map.fromList -- should not throw exceptions, i.e. no getBy404 or req
       allow <- appAllowDeprecated . appSettings <$> getYesod
       return $ bool (Unauthorized "Deprecated Route") Authorized allow
     )
+  ,("development", APHandler $ \r _ -> do
+      $logWarnS "AccessControl" ("route in development: " <> tshow r)
+#ifdef DEVELOPMENT
+      return Authorized
+#else
+      return $ Unauthorized "Route under development"
+#endif
+    )
   ,("lecturer", APDB $ \route _ -> case route of
       CourseR tid ssh csh _ -> exceptT return return $ do
           authId <- maybeExceptT AuthenticationRequired $ lift maybeAuthId
@@ -406,7 +406,7 @@ knownTags = Map.fromList -- should not throw exceptions, i.e. no getBy404 or req
         return Authorized
 
       CourseR tid ssh csh CRegisterR -> maybeT (unauthorizedI MsgUnauthorizedCourseTime) $ do
-        Entity cid Course{..} <- MaybeT . getBy $ TermSchoolCourseShort tid ssh csh
+        Entity _ Course{courseRegisterFrom, courseRegisterTo} <- MaybeT . getBy $ TermSchoolCourseShort tid ssh csh
         cTime <- (NTop . Just) <$> liftIO getCurrentTime
         guard $ NTop courseRegisterFrom <= cTime
              && NTop courseRegisterTo   >= cTime
@@ -414,7 +414,7 @@ knownTags = Map.fromList -- should not throw exceptions, i.e. no getBy404 or req
 
       MessageR cID -> maybeT (unauthorizedI MsgUnauthorizedSystemMessageTime) $ do
         smId <- decrypt cID
-        SystemMessage{..} <- MaybeT $ get smId
+        SystemMessage{systemMessageFrom, systemMessageTo} <- MaybeT $ get smId
         cTime <- (NTop . Just) <$> liftIO getCurrentTime
         guard $ NTop systemMessageFrom <= cTime
              && NTop systemMessageTo   >= cTime
@@ -617,14 +617,14 @@ instance Yesod UniWorX where
         
         errPage = case err of
           NotFound -> [whamlet|<p>_{MsgErrorResponseNotFound}|]
-          InternalError err -> encrypted err [whamlet|<p .errMsg>#{err}|]
+          InternalError err' -> encrypted err' [whamlet|<p .errMsg>#{err'}|]
           InvalidArgs errs -> [whamlet|
               <ul>
-                $forall err <- errs
-                  <li .errMsg>#{err}
+                $forall err' <- errs
+                  <li .errMsg>#{err'}
             |]
           NotAuthenticated -> [whamlet|<p>_{MsgErrorResponseNotAuthenticated}|]
-          PermissionDenied err -> [whamlet|<p .errMsg>#{err}|]
+          PermissionDenied err' -> [whamlet|<p .errMsg>#{err'}|]
           BadMethod method -> [whamlet|<p>_{MsgErrorResponseBadMethod (decodeUtf8 method)}|]
       fmap toTypedContent . siteLayout (Just . toHtml . mr $ ErrorResponseTitle err) $ do
         toWidget
@@ -746,8 +746,8 @@ siteLayout headingOverride widget = do
       asidenav = $(widgetFile "widgets/asidenav")
       contentHeadline :: Maybe Widget
       contentHeadline = (toWidget <$> headingOverride) <|> (pageHeading =<< mcurrentRoute)
-      breadcrumbs :: Widget
-      breadcrumbs = $(widgetFile "widgets/breadcrumbs")
+      breadcrumbsWgt :: Widget
+      breadcrumbsWgt = $(widgetFile "widgets/breadcrumbs")
       pageactionprime :: Widget
       pageactionprime = $(widgetFile "widgets/pageactionprime") -- TODO: rename, since it also shows secondary pageActions now
       -- functions to determine if there are page-actions (primary or secondary)
@@ -786,11 +786,13 @@ applySystemMessages = liftHandlerT . runDB . runConduit $ selectSource [] [] .|
   where
     applyMessage (Entity smId SystemMessage{..}) = maybeT_ $ do
       cID <- encrypt smId
+      void . assertM (== Authorized) . lift $ evalAccessDB (MessageR cID) False
+
       let sessionKey = "sm-" <> tshow (ciphertext cID)
-      assertM (== Authorized) . lift $ evalAccessDB (MessageR cID) False
-      assertM isNothing (lookupSessionJson sessionKey :: MaybeT (YesodDB UniWorX) (Maybe ()))
+      _ <- assertM isNothing $ lookupSessionJson sessionKey :: MaybeT (YesodDB UniWorX) (Maybe ())
       setSessionJson sessionKey ()
-      (SystemMessage{..}, smTrans) <- MaybeT $ getSystemMessage appLanguages smId
+
+      (_, smTrans) <- MaybeT $ getSystemMessage appLanguages smId
       let
         (summary, content) = case smTrans of
           Nothing -> (systemMessageSummary, systemMessageContent)
@@ -1177,11 +1179,12 @@ pageActions (CorrectionsR) =
       , menuItemModal = True
       , menuItemAccessCallback' = runDB $ do
           uid <- liftHandlerT requireAuthId
-          [E.Value count] <- E.select . E.from $ \(sheet `E.InnerJoin` sheetCorrector) -> do
+          [E.Value corrCount] <- E.select . E.from $ \(sheet `E.InnerJoin` sheetCorrector) -> do
             E.on $ sheetCorrector E.^. SheetCorrectorSheet E.==. sheet E.^. SheetId
             E.where_ $ sheet E.^. SheetSubmissionMode E.==. E.val CorrectorSubmissions
+                 E.&&. sheetCorrector E.^. SheetCorrectorUser E.==. E.val uid
             return E.countRows
-          return $ (count :: Int) /= 0
+          return $ (corrCount :: Int) /= 0
       }
   , PageActionPrime $ MenuItem
       { menuItemLabel = "Korrekturen eintragen"
@@ -1206,11 +1209,12 @@ pageActions (CorrectionsGradeR) =
       , menuItemModal = True
       , menuItemAccessCallback' = runDB $ do
           uid <- liftHandlerT requireAuthId
-          [E.Value count] <- E.select . E.from $ \(sheet `E.InnerJoin` sheetCorrector) -> do
+          [E.Value corrCount] <- E.select . E.from $ \(sheet `E.InnerJoin` sheetCorrector) -> do
             E.on $ sheetCorrector E.^. SheetCorrectorSheet E.==. sheet E.^. SheetId
             E.where_ $ sheet E.^. SheetSubmissionMode E.==. E.val CorrectorSubmissions
+                 E.&&. sheetCorrector E.^. SheetCorrectorUser E.==. E.val uid
             return E.countRows
-          return $ (count :: Int) /= 0
+          return $ (corrCount :: Int) /= 0
       }
   ]
 pageActions _ = []
@@ -1287,7 +1291,7 @@ pageHeading (CSheetR tid ssh csh shn SEditR)
   = Just $ i18nHeading $ MsgSheetEditHead tid ssh csh shn
 pageHeading (CSheetR tid ssh csh shn SDelR)
   = Just $ i18nHeading $ MsgSheetDelHead tid ssh csh shn
-pageHeading (CSheetR tid ssh csh shn SSubsR)
+pageHeading (CSheetR _tid _ssh _csh shn SSubsR)
   = Just $ i18nHeading $ MsgSubmissionsSheet shn
 pageHeading (CSheetR tid ssh csh shn SubmissionNewR)
   = Just $ i18nHeading $ MsgSubmissionEditHead tid ssh csh shn
@@ -1299,7 +1303,7 @@ pageHeading (CSubmissionR tid ssh csh shn _ SubShowR) -- TODO: Rethink this one!
 pageHeading (CSubmissionR tid ssh csh shn cid CorrectionR)
   = Just $ i18nHeading $ MsgCorrectionHead tid ssh csh shn cid
 --          (CSubmissionR tid csh shn cid SubDownloadR) -- just a download
-pageHeading (CSheetR tid ssh csh shn SCorrR)
+pageHeading (CSheetR _tid _ssh _csh shn SCorrR)
   = Just $ i18nHeading $ MsgCorrectorsHead shn
 --          (CSheetR tid ssh csh shn SFileR) -- just for Downloads
 
@@ -1542,7 +1546,7 @@ instance YesodMail UniWorX where
     pool <- maybe (throwM MailNotAvailable) return =<< getsYesod appSmtpPool
     withResource pool act
   mailT ctx mail = defMailT ctx $ do 
-    setMailObjectId
+    void setMailObjectId
     setDateCurrent
     replaceMailHeader "Auto-Submitted" $ Just "auto-generated"
   
diff --git a/src/Handler/Corrections.hs b/src/Handler/Corrections.hs
index 9e2285d40..44c32bb50 100644
--- a/src/Handler/Corrections.hs
+++ b/src/Handler/Corrections.hs
@@ -24,7 +24,7 @@ import Data.Semigroup (Sum(..))
 -- import qualified Data.Text as T
 -- import Data.Function ((&))
 --
-import Colonnade hiding (fromMaybe, singleton, bool)
+-- import Colonnade hiding (fromMaybe, singleton, bool)
 -- import Yesod.Colonnade
 --
 -- import qualified Data.UUID.Cryptographic as UUID
@@ -40,25 +40,19 @@ import qualified Database.Esqueleto as E
 import Web.PathPieces
 
 import Text.Hamlet (ihamletFile)
-import Text.Blaze.Html (preEscapedToHtml)
 
 import Database.Persist.Sql (updateWhereCount)
 
 import Data.List (genericLength)
 
-import Data.CaseInsensitive (CI)
-import qualified Data.CaseInsensitive as CI
-
-import Control.Monad.Trans.Writer (Writer, WriterT(..), runWriter)
-import Control.Monad.Writer.Class (MonadWriter(..))
+import Control.Monad.Trans.Writer (WriterT(..), runWriter)
 
 import Control.Monad.Trans.RWS (RWST)
 
-import Control.Monad.Trans.State (State, StateT(..), runState)
+import Control.Monad.Trans.State (State, runState)
 import qualified Control.Monad.State.Class as State
 
 import Data.Foldable (foldrM)
-import Data.Traversable (for)
 
 
 
@@ -131,16 +125,16 @@ colSubmittors = sortable Nothing (i18nCell MsgSubmissionUsers) $ \DBRow{ dbrOutp
   tid = course ^. _3
   ssh = course ^. _4
   link cid = CourseR tid ssh csh $ CUserR cid
-  cell = listCell (Map.toList users) $ \(userId, (User{..}, mPseudo)) ->
+  protoCell = listCell (Map.toList users) $ \(userId, (User{..}, mPseudo)) ->
     anchorCellM (link <$> encrypt userId) $ case mPseudo of
       Nothing -> nameWidget userDisplayName userSurname
       Just p  -> [whamlet|^{nameWidget userDisplayName userSurname} (#{review pseudonymText p})|]
-  in cell & cellAttrs <>~ [("class", "list--inline list--comma-separated")]
+  in protoCell & cellAttrs <>~ [("class", "list--inline list--comma-separated")]
 
 colSMatrikel :: IsDBTable m a => Colonnade _ CorrectionTableData (DBCell m a)
 colSMatrikel = sortable Nothing (i18nCell MsgMatrikelNr) $ \DBRow{ dbrOutput=(_, _, _, _, users) } -> let
-  cell = listCell (Map.toList users) $ \(userId, (User{..}, _)) -> anchorCellM (AdminUserR <$> encrypt userId) (maybe mempty toWidget userMatrikelnummer)
-  in cell & cellAttrs <>~ [("class", "list--inline list--comma-separated")]
+  protoCell = listCell (Map.toList users) $ \(userId, (User{..}, _)) -> anchorCellM (AdminUserR <$> encrypt userId) (maybe mempty toWidget userMatrikelnummer)
+  in protoCell & cellAttrs <>~ [("class", "list--inline list--comma-separated")]
   
 colRating :: IsDBTable m a => Colonnade _ CorrectionTableData (DBCell m a)
 colRating = sortable (Just "rating") (i18nCell MsgRating) $  \DBRow{ dbrOutput=(Entity subId Submission{..}, Entity _ Sheet{..}, course, _, _) } ->
@@ -344,12 +338,12 @@ correctionsR whereClause (formColonnade -> displayColumns) psValidator actions =
           addMessage Warning =<< withUrlRenderer ($(ihamletFile "templates/messages/submissionsAlreadyAssigned.hamlet") mr)
         let unassigned = Set.fromList subs `Set.difference` Set.fromList (entityKey <$> alreadyAssigned)
         when (not $ null unassigned) $ do
-          (assigned, unassigned) <- assignSubmissions shid (Just unassigned)
+          (assigned, stillUnassigned) <- assignSubmissions shid (Just unassigned)
           when (not $ null assigned) $
             addMessageI Success $ MsgUpdatedAssignedCorrectorsAuto (fromIntegral $ Set.size assigned)
-          when (not $ null unassigned) $ do
+          when (not $ null stillUnassigned) $ do
             mr <- (toHtml . ) <$> getMessageRender
-            unassigned' <- forM (Set.toList unassigned) $ \sid -> (encrypt sid :: DB CryptoFileNameSubmission) 
+            unassigned' <- forM (Set.toList stillUnassigned) $ \sid -> (encrypt sid :: DB CryptoFileNameSubmission) 
             addMessage Warning =<< withUrlRenderer ($(ihamletFile "templates/messages/submissionsNotAssignedAuto.hamlet") mr)
       redirect currentRoute
 
@@ -501,19 +495,17 @@ postCorrectionR tid ssh csh shn cid = do
       case corrResult of
         FormMissing -> return ()
         FormFailure errs -> mapM_ (addMessage Error . toHtml) errs
-        FormSuccess (rated, ratingPoints, ratingComment) -> do
+        FormSuccess (rated, ratingPoints', ratingComment') -> do
           runDBJobs $ do
             uid <- liftHandlerT requireAuthId
             now <- liftIO getCurrentTime
-
-            Submission{submissionRatingTime} <- getJust sub
           
             update sub [ SubmissionRatingBy      =. (uid <$ guard rated)
 -- SJ: I don't think we need to update AssignedTime here, since this is just for correction upload
 --                        , SubmissionRatingAssigned +=. (Just now) -- TODO: Should submissionRatingAssigned change here if userId changes?
                        , SubmissionRatingTime    =. (now <$ guard rated)
-                       , SubmissionRatingPoints  =. ratingPoints
-                       , SubmissionRatingComment =. ratingComment
+                       , SubmissionRatingPoints  =. ratingPoints'
+                       , SubmissionRatingComment =. ratingComment'
                        ]
 
             addMessageI Success $ bool MsgRatingDeleted MsgRatingUpdated rated
@@ -527,10 +519,10 @@ postCorrectionR tid ssh csh shn cid = do
       case uploadResult of
         FormMissing -> return ()
         FormFailure errs -> mapM_ (addMessage Error . toHtml) errs
-        FormSuccess fileSource -> do
+        FormSuccess fileUploads -> do
           uid <- requireAuthId
           
-          runDBJobs . runConduit $ transPipe (lift . lift) fileSource .| extractRatingsMsg .| sinkSubmission uid (Right sub) True
+          void . runDBJobs . runConduit $ transPipe (lift . lift) fileUploads .| extractRatingsMsg .| sinkSubmission uid (Right sub) True
 
           addMessageI Success MsgRatingFilesUpdated
           redirect $ CSubmissionR tid ssh csh shn cid CorrectionR
@@ -612,10 +604,9 @@ postCorrectionsCreateR = do
     FormMissing -> return ()
     FormFailure errs -> forM_ errs $ addMessage Error . toHtml
     FormSuccess (sid, pss) -> do
-      now <- liftIO getCurrentTime
       runDB $ do
         Sheet{..} <- get404 sid
-        (sps, unknown) <- fmap partition . forM pss . mapM $ \p -> maybe (Left p) Right <$> getBy (UniqueSheetPseudonym sid p)
+        (sps, unknown) <- fmap partitionEithers' . forM pss . mapM $ \p -> maybe (Left p) Right <$> getBy (UniqueSheetPseudonym sid p)
         forM_ unknown $ addMessageI Error . MsgUnknownPseudonym . review pseudonymText
         now <- liftIO getCurrentTime
         let
@@ -664,23 +655,18 @@ postCorrectionsCreateR = do
               E.where_ . E.exists . E.from $ \submissionGroupUser ->
                 E.where_ $ submissionGroupUser E.^. SubmissionGroupUserUser `E.in_` E.valList (map sheetPseudonymUser spGroup)
               return $ submissionGroup E.^. SubmissionGroupId
-            case (groups :: [E.Value SubmissionGroupId]) of
-              [x] -> do
-                subId <- insert submission
-                void . insert $ SubmissionEdit uid now subId
-                insertMany_ . flip map spGroup $ \SheetPseudonym{sheetPseudonymUser} -> SubmissionUser
+            if
+              | length (groups :: [E.Value SubmissionGroupId]) < 2
+                -> do
+                  subId <- insert submission
+                  void . insert $ SubmissionEdit uid now subId
+                  insertMany_ . flip map spGroup $ \SheetPseudonym{sheetPseudonymUser} -> SubmissionUser
                     { submissionUserUser = sheetPseudonymUser
                     , submissionUserSubmission = subId
                     }
-              [] -> do
-                subId <- insert submission
-                void . insert $ SubmissionEdit uid now subId
-                insertMany_ . flip map spGroup $ \SheetPseudonym{sheetPseudonymUser} -> SubmissionUser
-                    { submissionUserUser = sheetPseudonymUser
-                    , submissionUserSubmission = subId
-                    }               
-                addMessageI Warning $ MsgSheetNoRegisteredGroup sheetGroupDesc
-              _ -> addMessageI Error $ MsgSheetAmbiguousRegisteredGroup sheetGroupDesc
+                  when (null groups) $
+                    addMessageI Warning $ MsgSheetNoRegisteredGroup sheetGroupDesc
+              | otherwise -> addMessageI Error $ MsgSheetAmbiguousRegisteredGroup sheetGroupDesc
           NoGroups
             | [SheetPseudonym{sheetPseudonymUser}] <- spGroup
               -> do
@@ -704,15 +690,15 @@ postCorrectionsCreateR = do
   defaultLayout $ do
     $(widgetFile "corrections-create")
   where
-    partition :: [[Either a b]] -> ([[b]], [a])
-    partition = runWriter . mapM (WriterT . Identity . swap . partitionEithers) 
+    partitionEithers' :: [[Either a b]] -> ([[b]], [a])
+    partitionEithers' = runWriter . mapM (WriterT . Identity . swap . partitionEithers) 
     
     textToList :: Textarea -> Handler (Either UniWorXMessage [[Pseudonym]])
     textToList (map (map Text.strip . Text.splitOn ",") . filter (not . Text.null) . Text.lines . unTextarea -> ws)
       = let
           invalid :: [Text]
           valid :: [[Pseudonym]]
-          (valid, invalid) = partition $ map (map $ \w -> maybe (Left w) Right $ w ^? pseudonymText) ws
+          (valid, invalid) = partitionEithers' $ map (map $ \w -> maybe (Left w) Right $ w ^? pseudonymText) ws
         in case invalid of
              (i:_) -> return . Left $ MsgInvalidPseudonym i
              []    -> return $ Right valid
diff --git a/src/Handler/Course.hs b/src/Handler/Course.hs
index c9262a2b6..89b6a9e86 100644
--- a/src/Handler/Course.hs
+++ b/src/Handler/Course.hs
@@ -2,9 +2,7 @@ module Handler.Course where
 
 import Import hiding (catMaybes)
 
-import Control.Lens
 import Utils.Lens
-import Utils.TH
 -- import Utils.DB
 import Handler.Utils
 import Handler.Utils.Table.Cells
@@ -20,20 +18,15 @@ import qualified Data.Map as Map
 
 import qualified Data.CaseInsensitive as CI
 
-
-import Colonnade hiding (fromMaybe,bool)
--- import Yesod.Colonnade
-
 import qualified Database.Esqueleto as E
 
-import qualified Data.UUID.Cryptographic as UUID
 
 -- NOTE: Outdated way to use dbTable; see ProfileDataR Handler for a more recent method.
 type CourseTableData = DBRow (Entity Course, Int64, Bool, Entity School)
 
 colCourse :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
 colCourse = sortable (Just "course") (i18nCell MsgCourse)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, _, _, _) } ->
+          $ \DBRow{ dbrOutput=(Entity _ Course{..}, _, _, _) } ->
             anchorCell (CourseR courseTerm courseSchool courseShorthand CShowR)
               [whamlet|#{display courseName}|]
 
@@ -44,19 +37,19 @@ colCourseDescr = sortable (Just "course") (i18nCell MsgCourse) $ do
 
 colDescription :: IsDBTable m a => Colonnade Sortable CourseTableData (DBCell m a)
 colDescription = sortable Nothing (i18nCell MsgCourseDescription)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, _, _, _) } ->
+          $ \DBRow{ dbrOutput=(Entity _ Course{..}, _, _, _) } ->
             case courseDescription of
               Nothing      -> mempty
               (Just descr) -> cell $ modal "Beschreibung" (Right $ toWidget descr)
 
 colCShort :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
 colCShort = sortable (Just "cshort") (i18nCell MsgCourseShort)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, _, _, _) } ->
+          $ \DBRow{ dbrOutput=(Entity _ Course{..}, _, _, _) } ->
             anchorCell (CourseR courseTerm courseSchool courseShorthand CShowR) [whamlet|#{display courseShorthand}|]
 
 colCShortDescr :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
 colCShortDescr = sortable (Just "cshort") (i18nCell MsgCourseShort)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, _, _, _) } -> mappend
+          $ \DBRow{ dbrOutput=(Entity _ Course{..}, _, _, _) } -> mappend
             ( anchorCell (CourseR courseTerm courseSchool courseShorthand CShowR) [whamlet|#{display courseShorthand}|] )
             ( case courseDescription of
                 Nothing      -> mempty
@@ -70,7 +63,7 @@ colCShortDescr = sortable (Just "cshort") (i18nCell MsgCourseShort)
 
 colTerm :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
 colTerm = sortable (Just "term") (i18nCell MsgTerm)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, _, _, _) } ->
+          $ \DBRow{ dbrOutput=(Entity _ Course{..}, _, _, _) } ->
             anchorCell (TermCourseListR courseTerm) [whamlet|#{display courseTerm}|]
 
 colSchool :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
@@ -85,24 +78,24 @@ colSchoolShort = sortable (Just "schoolshort") (i18nCell MsgCourseSchoolShort)
 
 colRegFrom :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
 colRegFrom = sortable (Just "register-from") (i18nCell MsgRegisterFrom)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, _, _, _) } ->
+          $ \DBRow{ dbrOutput=(Entity _ Course{..}, _, _, _) } ->
             maybe mempty timeCell courseRegisterFrom
             -- cell $ traverse (formatTime SelFormatDateTime) courseRegisterFrom >>= maybe mempty toWidget
 
 colRegTo :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
 colRegTo = sortable (Just "register-to") (i18nCell MsgRegisterTo)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, _, _, _) } ->
-            cell $ traverse (formatTime SelFormatDateTime) courseRegisterTo >>= maybe mempty toWidget
+          $ \DBRow{ dbrOutput=(Entity _ Course{..}, _, _, _) } ->
+            maybe mempty timeCell courseRegisterTo
 
 colParticipants :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
 colParticipants = sortable (Just "participants") (i18nCell MsgCourseMembers)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, currentParticipants, _, _) } -> i18nCell $ case courseCapacity of
+          $ \DBRow{ dbrOutput=(Entity _ Course{..}, currentParticipants, _, _) } -> i18nCell $ case courseCapacity of
               Nothing -> MsgCourseMembersCount currentParticipants
-              Just max -> MsgCourseMembersCountLimited currentParticipants max
+              Just limit -> MsgCourseMembersCountLimited currentParticipants limit
 
 colRegistered :: IsDBTable m a => Colonnade _ CourseTableData (DBCell m a)
 colRegistered = sortable (Just "registered") (i18nCell MsgRegistered)
-          $ \DBRow{ dbrOutput=(Entity cid Course{..}, _, registered, _) } -> tickmarkCell registered
+          $ \DBRow{ dbrOutput=(_, _, registered, _) } -> tickmarkCell registered
 
 type CourseTableExpr = E.SqlExpr (Entity Course) `E.InnerJoin` E.SqlExpr (Entity School)
 
@@ -326,7 +319,6 @@ getCourseNewR = do
     FormFailure msgs -> forM_ msgs ((addMessage Error) . toHtml) >>
                         noTemplateAction
     FormSuccess (fmap TermKey -> mbTid, fmap SchoolKey -> mbSsh, mbCsh) -> do
-      uid <- requireAuthId
       oldCourses <- runDB $ do
         E.select $ E.from $ \course -> do
           whenIsJust mbTid $ \tid -> E.where_ $ course E.^. CourseTerm       E.==. E.val tid
@@ -403,8 +395,8 @@ postCDeleteR = error "TODO: implement getCDeleteR"
 -- | Course Creation and Editing
 -- | IMPORTANT: in case of Edit, Post/Get Request is provided with the same CourseForm template (cannot be Nothing),
 -- |            since an edit is identified via cfCourseId which is not contained in the received form data for security reasons!
-courseEditHandler :: Bool -> Maybe CourseForm -> Handler Html
-courseEditHandler isGet mbCourseForm = do
+courseEditHandler :: Bool -> Maybe CourseForm -> Handler Html -- FIXME: _isGet is not used
+courseEditHandler _isGet mbCourseForm = do
     aid <- requireAuthId -- TODO: Verify that Editor is owner of the Course to be Edited!!!
     ((result, formWidget), formEnctype) <- runFormPost $ newCourseForm mbCourseForm
     case result of
@@ -451,7 +443,7 @@ courseEditHandler isGet mbCourseForm = do
             old <- get cid
             case old of
               Nothing -> addMessageI Error MsgInvalidInput $> False
-              (Just oldCourse) -> do
+              (Just _) -> do
                 updOkay <- myReplaceUnique cid (  -- replaceUnique requires Eq Course, which we cannot have
                     Course  {  courseName            = cfName       res
                             ,  courseDescription     = cfDesc       res
@@ -598,18 +590,24 @@ validateCourse (CourseForm{..}) =
 
 
 getCUsersR :: TermId -> SchoolId -> CourseShorthand -> Handler Html
-getCUsersR tid ssh csh = undefined -- TODO
+getCUsersR = error "CUsersR: Not implemented"
 
 
 getCUserR :: TermId -> SchoolId -> CourseShorthand -> CryptoUUIDUser -> Handler Html
-getCUserR tid ssh csh uuid = do
-  uid <- decrypt uuid
+getCUserR _tid _ssh _csh uCId = do
+  -- Needs authorization check:
+  --
+  --   - User is current member of course
+  --   - User has submitted in course
+  --   - User is member of registered group for course
+  --   - User is corrector for course (?)
+  --   - User is lecturer for course (?)
+  uid <- decrypt uCId
   User{..} <- runDB $ get404 uid
-  defaultLayout $
+  defaultLayout $ -- TODO
     [whamlet|
-      <h1>TODO
-      <h2>Lecturer's Page for User ^{nameWidget userDisplayName userSurname}
+      <p>^{nameWidget userDisplayName userSurname}
     |]
 
 getCHiWisR :: TermId -> SchoolId -> CourseShorthand -> Handler Html
-getCHiWisR tid ssh csh = undefined -- TODO
+getCHiWisR = error "CHiWisR: Not implemented"
diff --git a/src/Handler/Home.hs b/src/Handler/Home.hs
index 8c93c4a17..03b0d3843 100644
--- a/src/Handler/Home.hs
+++ b/src/Handler/Home.hs
@@ -8,7 +8,6 @@ import qualified Data.Map as Map
 import qualified Data.Text as Text
 import Data.Text.Encoding (decodeUtf8')
 import Data.Time hiding (formatTime)
-import Data.Universe
 import Data.Universe.Helpers
 
 import Network.Wai (requestHeaderReferer)
diff --git a/src/Handler/School.hs b/src/Handler/School.hs
index 92f0d2ec0..9dad647e0 100644
--- a/src/Handler/School.hs
+++ b/src/Handler/School.hs
@@ -2,37 +2,9 @@ module Handler.School where
 
 import Import
 
--- import Control.Lens
--- import Utils.Lens
--- import Utils.TH
--- import Handler.Utils
--- import Handler.Utils.Table.Cells
---
--- -- import Data.Time
--- import qualified Data.Text as T
--- import Data.Function ((&))
--- -- import Yesod.Form.Bootstrap3
---
--- import qualified Data.Set as Set
--- import qualified Data.Map as Map
---
--- import Colonnade hiding (fromMaybe,bool)
---
--- import qualified Database.Esqueleto as E
---
--- import qualified Data.UUID.Cryptographic as UUID
-
-
 getSchoolListR :: Handler Html
-getSchoolListR = do
-  -- muid <- maybeAuthId
-  defaultLayout $ do
-    [whamlet|TODO: Liste aller Institute |] -- TODO
-
+getSchoolListR = error "getSchoolListR: Not implemented"
 
 getSchoolShowR :: SchoolId -> Handler Html
-getSchoolShowR ssh = do -- TODO
-  -- muid <- maybeAuthId
-  defaultLayout $ do
-    [whamlet|TODO: Informationen zu einem Institut |] -- TODO
+getSchoolShowR = error "getSchoolShowR: Not implemented"
 
diff --git a/src/Handler/Sheet.hs b/src/Handler/Sheet.hs
index 0a25a30a6..582344a3f 100644
--- a/src/Handler/Sheet.hs
+++ b/src/Handler/Sheet.hs
@@ -31,7 +31,7 @@ import Control.Monad.Writer (MonadWriter(..), execWriterT)
 
 -- import qualified Data.List as List
 
-import Control.Monad.Trans.Except (ExceptT(..), runExceptT, mapExceptT, throwE)
+import Control.Monad.Trans.Except (runExceptT, mapExceptT, throwE)
 
 import Network.Mime
 
@@ -39,8 +39,7 @@ import Data.Set (Set)
 import qualified Data.Set as Set
 import qualified Data.Map as Map
 
-import Data.Map (Map, (!), (!?))
-import qualified Data.Map as Map
+import Data.Map (Map, (!?))
 
 import Data.Monoid (Sum(..), Any(..))
 
@@ -54,10 +53,6 @@ import Control.Monad.Random.Class (MonadRandom(..))
 import Utils.Sql
 
 
-instance Eq (Unique Sheet) where
-  (CourseSheet cid1 name1) == (CourseSheet cid2 name2) =
-    cid1 == cid2 && name1 == name2
-
 {-
   * Implement Handlers
   * Implement Breadcrumbs in Foundation
@@ -182,8 +177,8 @@ getSheetListR tid ssh csh = do
               (Just (Entity sid Submission{..})) ->
                 let mkCid = encrypt sid
                     mkRoute = do
-                      cid <- mkCid
-                      return $ CSubmissionR tid ssh csh sheetName cid CorrectionR
+                      cid' <- mkCid
+                      return $ CSubmissionR tid ssh csh sheetName cid' CorrectionR
                     protoCell = anchorCellM mkRoute $(widgetFile "widgets/rating")
                 in protoCell & cellContents %~ (<* tell (sheetTypeSum (sheetType, submissionRatingPoints)))
       , sortable Nothing -- (Just "percent")
@@ -218,7 +213,7 @@ getSheetListR tid ssh csh = do
         , SortColumn $ \(sheet `E.LeftOuterJoin` _) -> sheet E.^. SheetActiveTo
         )
       , ( "rating"
-        , SortColumn $ \(_ `E.LeftOuterJoin` (submission `E.InnerJoin` submissionUser)) -> submission E.?. SubmissionRatingPoints
+        , SortColumn $ \(_sheet `E.LeftOuterJoin` (submission `E.InnerJoin` _submissionUser)) -> submission E.?. SubmissionRatingPoints
         )
 --    GitLab Issue $143: HOW TO SORT?
 --       , ( "percent"
@@ -254,9 +249,7 @@ instance Button UniWorX ButtonGeneratePseudonym where
 -- Show single sheet
 getSShowR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> Handler Html
 getSShowR tid ssh csh shn = do
-  entSheet <- runDB $ fetchSheet tid ssh csh shn
-  let sheet = entityVal entSheet
-      sid   = entityKey entSheet
+  Entity sid sheet <- runDB $ fetchSheet tid ssh csh shn
   -- without Colonnade
 --   fileNameTypes <- runDB $ E.select $ E.from $
 --     \(sheet `E.InnerJoin` sheetFile `E.InnerJoin` file) -> do
@@ -270,19 +263,20 @@ getSShowR tid ssh csh shn = do
 --   let fileLinks = map (\(E.Value fName, E.Value modified, E.Value fType) -> (CSheetR tid ssh csh (SheetFileR shn fType fName),modified)) fileNameTypes
   -- with Colonnade
 
-  let fileData (sheet `E.InnerJoin` sheetFile `E.InnerJoin` file) = do
+  let fileData (sheet' `E.InnerJoin` sheetFile `E.InnerJoin` file) = do
         -- Restrict to consistent rows that correspond to each other
         E.on (file      E.^. FileId           E.==. sheetFile E.^. SheetFileFile)
-        E.on (sheetFile E.^. SheetFileSheet E.==. sheet     E.^. SheetId)
+        E.on (sheetFile E.^. SheetFileSheet   E.==. sheet'    E.^. SheetId)
         -- filter to requested file
-        E.where_ $  sheet     E.^. SheetId      E.==. E.val sid
+        E.where_ $  sheet'    E.^. SheetId      E.==. E.val sid
               E.&&. E.not_ (E.isNothing $ file E.^. FileContent)
         -- return desired columns
         return $ (file E.^. FileTitle, file E.^. FileModified, sheetFile E.^. SheetFileType)
   let colonnadeFiles = widgetColonnade $ mconcat
         [ sortable (Just "type") "Typ" $ \(_,_, E.Value ftype) -> i18nCell ftype & cellContents %~ (\act -> act <* tell (Any True))
-        , sortable (Just "path") "Dateiname" $ anchorCell' (\(E.Value fName,_,E.Value fType) -> CSheetR tid ssh csh shn (SFileR fType fName))
-                                                           (\(E.Value fName,_,_) -> str2widget fName)
+        , sortable (Just "path") "Dateiname" $ \(E.Value fName,_,E.Value fType) -> anchorCell
+            (CSheetR tid ssh csh shn (SFileR fType fName))
+            (str2widget fName)
         , sortable (Just "time") "Modifikation" $ \(_,E.Value modified,_) -> cell $ formatTime SelFormatDateTime (modified :: UTCTime) >>= toWidget
         ]
   let psValidator = def
@@ -297,13 +291,13 @@ getSShowR tid ssh csh shn = do
     , dbtIdent = "files" :: Text
     , dbtSorting = Map.fromList
       [ ( "type"
-        , SortColumn $ \(sheet `E.InnerJoin` sheetFile `E.InnerJoin` file) -> sheetFile E.^. SheetFileType
+        , SortColumn $ \(_sheet `E.InnerJoin` sheetFile `E.InnerJoin` _file) -> sheetFile E.^. SheetFileType
         )
       , ( "path"
-        , SortColumn $ \(sheet `E.InnerJoin` sheetFile `E.InnerJoin` file) -> file E.^. FileTitle
+        , SortColumn $ \(_sheet `E.InnerJoin` _sheetFile `E.InnerJoin` file) -> file E.^. FileTitle
         )
       , ( "time"
-        , SortColumn $ \(sheet `E.InnerJoin` sheetFile `E.InnerJoin` file) -> file E.^. FileModified
+        , SortColumn $ \(_sheet `E.InnerJoin` _sheetFile `E.InnerJoin` file) -> file E.^. FileModified
         )
       ]
     }
@@ -329,7 +323,7 @@ getSShowR tid ssh csh shn = do
     solutionFrom <- traverse (formatTime SelFormatDateTime) $ sheetSolutionFrom sheet
     $(widgetFile "sheetShow")
 
-postSPseudonymR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> Handler TypedContent
+getSPseudonymR, postSPseudonymR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> Handler TypedContent
 getSPseudonymR = postSPseudonymR
 postSPseudonymR tid ssh csh shn = do
   uid <- requireAuthId
@@ -373,7 +367,6 @@ getSFileR tid ssh csh shn typ title = do
         )
       -- return desired columns
       return $ (file E.^. FileTitle, file E.^. FileContent)
-  let mimeType = defaultMimeLookup $ pack title
   case results of
     [(E.Value fileTitle, E.Value fileContent)]
       | Just fileContent' <- fileContent -> do
@@ -426,12 +419,10 @@ postSheetNewR = getSheetNewR
 
 getSEditR :: TermId -> SchoolId -> CourseShorthand -> SheetName -> Handler Html
 getSEditR tid ssh csh shn = do
-  (sheetEnt, sheetFileIds) <- runDB $ do
+  (Entity sid Sheet{..}, sheetFileIds) <- runDB $ do
     ent <- fetchSheet tid ssh csh shn
     fti <- getFtIdMap $ entityKey ent
     return (ent, fti)
-  let sid = entityKey sheetEnt
-  let oldSheet@(Sheet {..}) = entityVal sheetEnt
   let template = Just $ SheetForm
         { sfName         = sheetName
         , sfDescription  = sheetDescription
@@ -530,7 +521,6 @@ getSDelR tid ssh csh shn = do
       submissionno <- runDB $ do
           sid <- fetchSheetId tid ssh csh shn
           count [SubmissionSheet ==. sid]
-      let formTitle = MsgSheetDelHead tid ssh csh shn
       let formText  = Just $ MsgSheetDelText submissionno
       let actionUrl = CSheetR tid ssh csh shn SDelR
       defaultLayout $ do
@@ -605,7 +595,7 @@ correctorForm shid = do
   let
     guardNonDeleted :: UserId -> Handler (Maybe UserId)
     guardNonDeleted uid = do
-      cID@CryptoID{..} <- encrypt uid :: Handler CryptoUUIDUser
+      CryptoID{ciphertext} <- encrypt uid :: Handler CryptoUUIDUser
       deleted <- lookupPostParam $ tshow ciphertext <> "-" <> "del"
       return $ bool Just (const Nothing) (isJust deleted) uid
   formCIDs <- mapM decrypt =<< catMaybes <$> liftHandlerT (map fromPathPiece <$> lookupPostParams cListIdent :: Handler [Maybe CryptoUUIDUser])
@@ -627,7 +617,7 @@ correctorForm shid = do
   let
     tutorField :: Field Handler [UserEmail]
     tutorField = convertField (map CI.mk) (map CI.original) $ multiEmailField
-      { fieldView = \theId name attrs val isReq -> asWidgetT $ do
+      { fieldView = \theId name attrs _val isReq -> asWidgetT $ do
           listIdent <- newIdent
           userId <- handlerToWidget requireAuthId
           previousCorrectors <- handlerToWidget . runDB . E.select . E.from $ \(user `E.InnerJoin` sheetCorrector `E.InnerJoin` sheet `E.InnerJoin` course `E.InnerJoin` lecturer) -> E.distinctOnOrderBy [E.asc $ user E.^. UserEmail ] $ do
@@ -667,7 +657,7 @@ correctorForm shid = do
   let
     constructFields :: (UserId, Text, (CorrectorState, Load)) -> MForm Handler CorrectorForm
     constructFields (uid, uname, (state, Load{..})) = do
-      cID@CryptoID{..} <- encrypt uid :: MForm Handler CryptoUUIDUser
+      CryptoID{ciphertext} <- encrypt uid :: MForm Handler CryptoUUIDUser
       let
         fs name = ""
           { fsName = Just $ tshow ciphertext <> "-" <> name
@@ -722,7 +712,7 @@ correctorForm shid = do
                            { fvLabel = text $ mr MsgCorrectors
                            , fvTooltip = Nothing
                            , fvId = ""
-                           , fvInput = Yesod.encodeCellTable tableDefault corrColonnade corrData >> mapM_ idField corrData >> mapM_ delField deletions
+                           , fvInput = Yesod.encodeCellTable tableDefault corrColonnade corrData >> mapM_ idField corrData >> mapM_ delField deletions'
                            , fvErrors = Nothing
                            , fvRequired = True
                            }
@@ -747,9 +737,9 @@ getSCorrR tid ssh csh shn = do
 
   case res of
     FormFailure errs -> mapM_ (addMessage Error . toHtml) errs
-    FormSuccess res -> runDB $ do
+    FormSuccess res' -> runDB $ do
       deleteWhere [SheetCorrectorSheet ==. shid]
-      insertMany_ $ Set.toList res
+      insertMany_ $ Set.toList res'
       addMessageI Success MsgCorrectorsUpdated
     FormMissing -> return ()
 
diff --git a/src/Handler/Submission.hs b/src/Handler/Submission.hs
index 25cac807d..7c3b0d3ba 100644
--- a/src/Handler/Submission.hs
+++ b/src/Handler/Submission.hs
@@ -19,7 +19,6 @@ import Network.Mime
 import Data.Monoid (Any(..))
 import Data.Maybe (fromJust)
 -- import qualified Data.Maybe
-import qualified Data.Text as Text
 import qualified Data.Text.Encoding as Text
 
 import Data.CaseInsensitive (CI)
@@ -51,11 +50,11 @@ import System.FilePath
 makeSubmissionForm :: Maybe SubmissionId -> UploadMode -> SheetGroup -> [UserEmail] -> Form (Maybe (Source Handler File), [UserEmail])
 makeSubmissionForm msmid uploadMode grouping buddies = identForm FIDsubmission $ \html -> do
     let
-      fileUpload = case uploadMode of
+      fileUploadForm = case uploadMode of
         NoUpload -> pure Nothing
         (Upload unpackZips) -> (bool (\f fs _ -> Just <$> areq f fs Nothing) aopt $ isJust msmid) (zipFileField unpackZips) (fsm $ bool MsgSubmissionFile MsgSubmissionArchive unpackZips) Nothing
     flip (renderAForm FormStandard) html $ (,)
-      <$> fileUpload
+      <$> fileUploadForm
       <*> (catMaybes <$> sequenceA [bool aforced' aopt editableBuddies ciField (fslpI (MsgSubmissionMember g) "user@campus.lmu.de" ) buddy
                                     | g <- [1..(max (fromIntegral groupNr) $ length buddies)] -- groupNr might have decreased meanwhile
                                     | buddy <- map (Just . Just) buddies ++ repeat Nothing -- show current buddies
@@ -138,6 +137,8 @@ submissionHelper tid ssh csh shn (SubmissionMode mcid) = do
         void $ submissionMatchesSheet tid ssh csh shn (fromJust mcid)
         
         shid' <- submissionSheet <$> get404 smid
+        unless (shid == shid') $
+          invalidArgsI [MsgSubmissionWrongSheet]
         -- fetch buddies from current submission
         (Any isOwner, buddies) <- do
           submittors <- E.select . E.from $ \(submissionUser `E.InnerJoin` user) -> do
@@ -212,7 +213,6 @@ submissionHelper tid ssh csh shn (SubmissionMode mcid) = do
 
     case res' of
       (FormSuccess (mFiles,(setFromList -> adhocIds))) -> do
-        now <- liftIO $ getCurrentTime
         smid <- do
           smid <- case (mFiles, msmid) of
             (Nothing, Just smid)   -- no new files, existing submission partners updated
@@ -298,10 +298,10 @@ submissionHelper tid ssh csh shn (SubmissionMode mcid) = do
         , dbtIdent = "files" :: Text
         , dbtSorting = Map.fromList
           [ ( "path"
-            , SortColumn $ \((sf1 `E.InnerJoin` f1) `E.FullOuterJoin` (sf2 `E.InnerJoin` f2)) -> E.coalesce [f1 E.?. FileTitle, f2 E.?. FileTitle]
+            , SortColumn $ \((_sf1 `E.InnerJoin` f1) `E.FullOuterJoin` (_sf2 `E.InnerJoin` f2)) -> E.coalesce [f1 E.?. FileTitle, f2 E.?. FileTitle]
             )
           , ( "time"
-            , SortColumn $ \((sf1 `E.InnerJoin` f1) `E.FullOuterJoin` (sf2 `E.InnerJoin` f2)) -> (E.unsafeSqlFunction "GREATEST" ([f1 E.?. FileModified, f2 E.?. FileModified] :: [E.SqlExpr (E.Value (Maybe UTCTime))]) :: E.SqlExpr (E.Value (Maybe UTCTime)))
+            , SortColumn $ \((_sf1 `E.InnerJoin` f1) `E.FullOuterJoin` (_sf2 `E.InnerJoin` f2)) -> (E.unsafeSqlFunction "GREATEST" ([f1 E.?. FileModified, f2 E.?. FileModified] :: [E.SqlExpr (E.Value (Maybe UTCTime))]) :: E.SqlExpr (E.Value (Maybe UTCTime)))
             )
           ]
         , dbtFilter = Map.empty
@@ -341,7 +341,6 @@ getSubDownloadR tid ssh csh shn cID (submissionFileTypeIsUpdate -> isUpdate) pat
                -- E.&&. E.not_ (E.isNothing $ f E.^. FileContent) -- This is fine, we just return 204
           return f
 
-        let fileName = Text.pack $ takeFileName path
         case results of
           [Entity _ File{ fileContent = Just c, fileTitle }] -> do
             whenM downloadFiles $ 
@@ -367,7 +366,7 @@ getSubArchiveR tid ssh csh shn cID (ZIPArchiveName sfType) = do
     rating <- lift $ getRating submissionID
 
     let
-      fileSource = case sfType of
+      fileSelect = case sfType of
         SubmissionOriginal -> E.selectSource . E.from $ \(sf `E.InnerJoin` f) -> do
           E.on $ f E.^. FileId E.==. sf E.^. SubmissionFileFile
           E.where_ $ sf E.^. SubmissionFileSubmission E.==. E.val submissionID
@@ -376,7 +375,7 @@ getSubArchiveR tid ssh csh shn cID (ZIPArchiveName sfType) = do
         _ -> submissionFileSource submissionID
 
       fileSource' = do
-        fileSource .| Conduit.map entityVal
+        fileSelect .| Conduit.map entityVal
         when (sfType == SubmissionCorrected) $
           maybe (return ()) (yieldM . ratingFile cID) rating
 
diff --git a/src/Handler/SystemMessage.hs b/src/Handler/SystemMessage.hs
index 487b79331..647d1e273 100644
--- a/src/Handler/SystemMessage.hs
+++ b/src/Handler/SystemMessage.hs
@@ -68,23 +68,9 @@ postMessageR cID = do
           <*> aopt htmlField' (fslpI MsgSystemMessageSummary "HTML") Nothing
           <* submitButton
 
-      formResult modifyRes $ \SystemMessage{..} -> do
-        runDB $ update smId
-          [ SystemMessageFrom =. systemMessageFrom
-          , SystemMessageTo =. systemMessageTo
-          , SystemMessageAuthenticatedOnly =. systemMessageAuthenticatedOnly
-          , SystemMessageSeverity =. systemMessageSeverity
-          , SystemMessageDefaultLanguage =. systemMessageDefaultLanguage
-          , SystemMessageContent =. systemMessageContent
-          , SystemMessageSummary =. systemMessageSummary
-          ]
-        addMessageI Success MsgSystemMessageEditSuccess
-        redirect $ MessageR cID
+      formResult modifyRes $ modifySystemMessage smId
 
-      formResult addTransRes $ \smt -> do
-        runDB . void . insert $ smt
-        addMessageI Success MsgSystemMessageAddTranslationSuccess
-        redirect $ MessageR cID
+      formResult addTransRes addTranslation
 
       forM_ modifyTranss . flip formResult $ \(Entity tId SystemMessageTranslation{..}, (catMaybes -> acts)) -> case acts of
         [BtnDelete'] -> do
@@ -127,7 +113,24 @@ postMessageR cID = do
   
   defaultLayout $ do
     $(widgetFile "system-message")
+  where
+    modifySystemMessage smId SystemMessage{..} = do
+      runDB $ update smId
+        [ SystemMessageFrom =. systemMessageFrom
+        , SystemMessageTo =. systemMessageTo
+        , SystemMessageAuthenticatedOnly =. systemMessageAuthenticatedOnly
+        , SystemMessageSeverity =. systemMessageSeverity
+        , SystemMessageDefaultLanguage =. systemMessageDefaultLanguage
+        , SystemMessageContent =. systemMessageContent
+        , SystemMessageSummary =. systemMessageSummary
+        ]
+      addMessageI Success MsgSystemMessageEditSuccess
+      redirect $ MessageR cID
 
+    addTranslation translation = do
+      runDB . void $ insert translation
+      addMessageI Success MsgSystemMessageAddTranslationSuccess
+      redirect $ MessageR cID
 
 type MessageListData = DBRow (Entity SystemMessage, Maybe SystemMessageTranslation)
 
@@ -223,8 +226,8 @@ postMessageListR = do
           runDB $ updateWhere [ SystemMessageId <-. selection' ] [ SystemMessageTo =. ts ]
           $(addMessageFile Success "templates/messages/systemMessagesSetTo.hamlet")
           redirect MessageListR
-    FormSuccess (_, selection)
-      | null selection -> addMessageI Error MsgSystemMessageEmptySelection
+    FormSuccess (_, _selection) -- prop> null _selection
+      -> addMessageI Error MsgSystemMessageEmptySelection
 
   ((addRes, addView), addEncoding) <- runFormPost . identForm FIDSystemMessageAdd . renderAForm FormStandard $ SystemMessage
     <$> aopt utcTimeField (fslI MsgSystemMessageFrom) Nothing
diff --git a/src/Handler/Term.hs b/src/Handler/Term.hs
index 611a4cc9a..8507168e7 100644
--- a/src/Handler/Term.hs
+++ b/src/Handler/Term.hs
@@ -60,9 +60,9 @@ getTermShowR = do
     provideRep $ toJSON . map fst <$> runDB (E.select $ E.from termData)
     provideRep $ do
       let colonnadeTerms = widgetColonnade $ mconcat
-            [ sortable Nothing "Kürzel" $
-                anchorCell' (\(Entity tid _, _) -> TermCourseListR tid)
-                            (\(Entity tid _, _) -> [whamlet|#{toPathPiece tid}|])
+            [ sortable Nothing "Kürzel" $ \(Entity tid _, _) -> anchorCell
+                (TermCourseListR tid)
+                [whamlet|#{toPathPiece tid}|]
             , sortable (Just "lecture-start") (i18nCell MsgLectureStart) $ \(Entity _ Term{..},_) ->
                 cell $ formatTime SelFormatDate termLectureStart >>= toWidget
             , sortable (Just "lecture-end") "Ende Vorlesungen"   $ \(Entity _ Term{..},_) ->
diff --git a/src/Handler/Utils/DateTime.hs b/src/Handler/Utils/DateTime.hs
index dcacedadb..f5db92758 100644
--- a/src/Handler/Utils/DateTime.hs
+++ b/src/Handler/Utils/DateTime.hs
@@ -20,8 +20,6 @@ import qualified Data.Time.Format as Time
 import Data.Set (Set)
 import qualified Data.Set as Set
 
-import Mail
-
 utcToLocalTime :: UTCTime -> LocalTime
 utcToLocalTime = TZ.utcToLocalTimeTZ appTZ
 
diff --git a/src/Handler/Utils/Form.hs b/src/Handler/Utils/Form.hs
index cc3d146fc..bdf9490d9 100644
--- a/src/Handler/Utils/Form.hs
+++ b/src/Handler/Utils/Form.hs
@@ -6,16 +6,12 @@ module Handler.Utils.Form
 import Utils.Form
 
 import Handler.Utils.Form.Types
-import Handler.Utils.Templates
 
 import Handler.Utils.DateTime
-import qualified Data.Time as Time
 
 import Import hiding (cons)
 import qualified Data.Char as Char
-import Data.String (IsString(..))
 
-import Data.CaseInsensitive (CI)
 import qualified Data.CaseInsensitive as CI
 
 import qualified Data.Foldable as Foldable
@@ -32,10 +28,8 @@ import Handler.Utils.Zip
 import qualified Data.Conduit.List as C
 
 import qualified Database.Esqueleto as E
-import qualified Database.Esqueleto.Internal.Sql as E
 
 import Data.Set (Set)
-import qualified Data.Set as Set
 
 import Data.Map (Map)
 import qualified Data.Map as Map
@@ -287,7 +281,7 @@ multiFileField permittedFiles' = Field{..}
       mapM_ handleFile files .| C.map Right
       where
         doUnpack = unpackZips `elem` vals
-    fieldView fieldId fieldName attrs val req = do
+    fieldView fieldId fieldName _attrs val req = do
       pVals <- handlerToWidget permittedFiles'
       sentVals <- for val $ \src -> handlerToWidget . sourceToList $ src .| takeLefts
       let
@@ -507,7 +501,7 @@ optionsPersistCryptoId filts ords toDisplay = fmap mkOptionList $ do
   mr <- getMessageRender
   pairs <- runDB $ selectList filts ords
   cPairs <- forM pairs $ \e@(Entity key _) -> (,) <$> encrypt key <*> pure e
-  return $ map (\(cId, e@(Entity key value)) -> Option
+  return $ map (\(cId, e@(Entity _key value)) -> Option
                  { optionDisplay = mr (toDisplay value)
                  , optionInternalValue = e
                  , optionExternalValue = toPathPiece (cId :: CryptoID UUID (Key a))
@@ -575,7 +569,7 @@ multiAction acts defAction = do
       mToWidget aForm = Just . snd <$> renderAForm FormStandard (formToAForm $ return aForm) mempty
   widgets <- mapM mToWidget results
   let actionWidgets = Map.foldrWithKey accWidget [] widgets
-      accWidget act Nothing = id
+      accWidget _act Nothing = id
       accWidget act (Just w) = cons $(widgetFile "widgets/multiAction")
       actionResults = Map.map fst results
   return ((actionResults Map.!) =<< actionRes, $(widgetFile "widgets/multiActionCollect"))
diff --git a/src/Handler/Utils/Mail.hs b/src/Handler/Utils/Mail.hs
index 4ade0952d..5c35dd4aa 100644
--- a/src/Handler/Utils/Mail.hs
+++ b/src/Handler/Utils/Mail.hs
@@ -4,7 +4,7 @@ module Handler.Utils.Mail
   , addFileDB
   ) where
 
-import Import hiding ((.=))
+import Import
 
 import Utils.Lens hiding (snoc)
 
diff --git a/src/Handler/Utils/Rating.hs b/src/Handler/Utils/Rating.hs
index b5438b299..dc8bbc8dd 100644
--- a/src/Handler/Utils/Rating.hs
+++ b/src/Handler/Utils/Rating.hs
@@ -149,10 +149,10 @@ parseRating :: MonadThrow m => File -> m Rating'
 parseRating File{ fileContent = Just input, .. } = do
   inputText <- either (throw . RatingNotUnicode) return $ Text.decodeUtf8' input
   let
-    (headerLines', commentLines) = break (sep `Text.isInfixOf`) $ Text.lines inputText
-    (reverse -> ratingLines, reverse -> headerLines) = break (sep' `Text.isInfixOf`) $ reverse headerLines'
+    (headerLines', commentLines) = break (commentSep `Text.isInfixOf`) $ Text.lines inputText
+    (reverse -> ratingLines, reverse -> _headerLines) = break (sep' `Text.isInfixOf`) $ reverse headerLines'
     ratingLines' = filter (rating `Text.isInfixOf`) ratingLines
-    sep = "Beginn der Kommentare"
+    commentSep = "Beginn der Kommentare"
     sep' = Text.pack $ replicate 40 '='
     rating = "Bewertung:"
   comment' <- case commentLines of
@@ -162,7 +162,7 @@ parseRating File{ fileContent = Just input, .. } = do
     ratingComment
       | Text.null comment' = Nothing
       | otherwise = Just comment'
-  ratingLine' <- case ratingLines of
+  ratingLine' <- case ratingLines' of
     [l] -> return l
     _ -> throw RatingMultiple
   let
diff --git a/src/Handler/Utils/Submission.hs b/src/Handler/Utils/Submission.hs
index 78f836f46..e6cbe3c37 100644
--- a/src/Handler/Utils/Submission.hs
+++ b/src/Handler/Utils/Submission.hs
@@ -9,13 +9,11 @@ module Handler.Utils.Submission
   , submissionMatchesSheet
   ) where
 
-import Import hiding ((.=), joinPath)
+import Import hiding (joinPath)
 import Jobs
 import Prelude (lcm)
 import Yesod.Core.Types (HandlerContents(..), ErrorResponse(..))
 
-import Control.Lens
-import Control.Lens.Extras (is)
 import Utils.Lens
 
 import Control.Monad.State hiding (forM_, mapM_,foldM)
@@ -29,15 +27,12 @@ import Data.Maybe ()
 import qualified Data.List as List
 import Data.Set (Set)
 import qualified Data.Set as Set
-import Data.Map (Map, (!?))
+import Data.Map (Map)
 import qualified Data.Map as Map
 
 import qualified Data.Text as Text
 import Data.Ratio
 
-import Data.CaseInsensitive (CI)
-import qualified Data.CaseInsensitive as CI
-
 import Data.Monoid (Monoid, Any(..), Sum(..))
 import Generics.Deriving.Monoid (memptydefault, mappenddefault)
 
@@ -49,7 +44,6 @@ import Handler.Utils.Submission.TH
 
 import qualified Database.Esqueleto as E
 
-import Data.Conduit
 import qualified Data.Conduit.List as Conduit
 import Data.Conduit.ResumableSink
 
@@ -76,7 +70,7 @@ assignSubmissions sid restriction = do
     Sheet{..} <- getJust sid
     correctors <- selectList [ SheetCorrectorSheet ==. sid, SheetCorrectorState ==. CorrectorNormal ] []
     let
-      byTutorial' uid = join . Map.lookup uid $ Map.fromList [ (sheetCorrectorUser, byTutorial sheetCorrectorLoad) | Entity _ SheetCorrector{..} <- corrsTutorial ]
+      -- byTutorial' uid = join . Map.lookup uid $ Map.fromList [ (sheetCorrectorUser, byTutorial sheetCorrectorLoad) | Entity _ SheetCorrector{..} <- corrsTutorial ]
       corrsTutorial = filter hasTutorialLoad correctors -- needed as List within Esqueleto
       corrsProp  = filter hasPositiveLoad correctors
       countsToLoad' :: UserId -> Bool
@@ -118,7 +112,7 @@ assignSubmissions sid restriction = do
     let
       prevSubs' :: Map SheetId (Map UserId (Rational, Integer))
       prevSubs' = Map.unionsWith (Map.unionWith $ \(prop, n) (_, n') -> (prop, n + n')) $ do
-        (Entity _ sc@SheetCorrector{ sheetCorrectorLoad = Load{..}, .. }, E.Value isByTutorial, E.Value isPlaceholder) <- prevSubs
+        (Entity _ SheetCorrector{ sheetCorrectorLoad = Load{..}, .. }, E.Value isByTutorial, E.Value isPlaceholder) <- prevSubs
         guard $ maybe True (not isByTutorial ||) byTutorial
         let proportion
               | CorrectorExcused <- sheetCorrectorState = 0
@@ -311,9 +305,9 @@ extractRatingsMsg :: ( MonadHandler m
                      ) => Conduit File m SubmissionContent
 extractRatingsMsg = do
   ignored' <- filterSubmission `fuseUpstream` Rating.extractRatings
-  let ignored :: Set (Either CryptoFileNameSubmission FilePath)
-      ignored = Right `Set.map` ignored'
-  unless (null ignored) $ do
+  let ignoredFiles :: Set (Either CryptoFileNameSubmission FilePath)
+      ignoredFiles = Right `Set.map` ignored'
+  unless (null ignoredFiles) $ do
     mr <- (toHtml . ) <$> getMessageRender
     addMessage Warning =<< withUrlRenderer ($(ihamletFile "templates/messages/submissionFilesIgnored.hamlet") mr)
 
@@ -346,20 +340,19 @@ sinkSubmission userId mExists isUpdate = do
       return sId
     Right sId -> return sId
 
-  sId <$ sinkSubmission' sId isUpdate
+  sId <$ sinkSubmission' sId
   where
-    tell = modify . mappend
+    tellSt = modify . mappend
 
     sinkSubmission' :: SubmissionId
-                    -> Bool -- ^ Is this a correction
                     -> Sink SubmissionContent (YesodJobDB UniWorX) ()
-    sinkSubmission' submissionId isUpdate = lift . finalize <=< execStateLC mempty . Conduit.mapM_ $ \case
+    sinkSubmission' submissionId = lift . finalize <=< execStateLC mempty . Conduit.mapM_ $ \case
       Left file@(File{..}) -> do
         $logDebugS "sinkSubmission" . tshow $ (submissionId, fileTitle)
 
         alreadySeen <- gets (Set.member fileTitle . sinkFilenames)
         when alreadySeen . throwM $ DuplicateFileTitle fileTitle
-        tell $ mempty{ sinkFilenames = Set.singleton fileTitle  }
+        tellSt $ mempty{ sinkFilenames = Set.singleton fileTitle  }
 
         otherVersions <- lift . E.select . E.from $ \(sf `E.InnerJoin` f) -> do
           E.on $ sf E.^. SubmissionFileFile E.==. f E.^. FileId
@@ -411,7 +404,7 @@ sinkSubmission userId mExists isUpdate = do
         
         alreadySeen <- gets $ getAny . sinkSeenRating
         when alreadySeen $ throwM DuplicateRating
-        tell $ mempty{ sinkSeenRating = Any True }
+        tellSt $ mempty{ sinkSeenRating = Any True }
 
         unless isUpdate $ throwM RatingWithoutUpdate
 
@@ -459,10 +452,10 @@ sinkSubmission userId mExists isUpdate = do
               False -> lift . insert_ $ SubmissionEdit userId now submissionId
               True  -> do
                 Submission{submissionRatingTime} <- lift $ getJust submissionId
-                when (isNothing submissionRatingTime) $ tell mempty { sinkSubmissionNotifyRating = Any True }
+                when (isNothing submissionRatingTime) $ tellSt mempty { sinkSubmissionNotifyRating = Any True }
                 lift $ update submissionId [ SubmissionRatingBy =. Just userId, SubmissionRatingTime =. Just now ]
                 -- TODO: Should submissionRatingAssigned change here if userId changes?
-            tell $ mempty{ sinkSubmissionTouched = Any True }
+            tellSt $ mempty{ sinkSubmissionTouched = Any True }
 
         finalize :: SubmissionSinkState -> YesodJobDB UniWorX ()
         finalize SubmissionSinkState{..} = do
@@ -515,9 +508,9 @@ sinkSubmission userId mExists isUpdate = do
 
 data SubmissionMultiSinkException
   = SubmissionSinkException
-    { submissionSinkId :: CryptoFileNameSubmission
-    , submissionSinkFedFile :: Maybe FilePath
-    , submissionSinkException :: SubmissionSinkException
+    { _submissionSinkId :: CryptoFileNameSubmission
+    , _submissionSinkFedFile :: Maybe FilePath
+    , _submissionSinkException :: SubmissionSinkException
     }                                   
   deriving (Typeable, Show)
 
@@ -559,7 +552,7 @@ sinkMultiSubmission userId isUpdate = do
       case sink' of
         Left _ -> error "sinkSubmission returned prematurely"
         Right nSink -> modify $ Map.insert sId nSink
-  (sinks, ignored) <- execRWSLC () Map.empty . awaitForever $ \case
+  (sinks, ignoredFiles) <- execRWSLC () Map.empty . awaitForever $ \case
     v@(Right (sId, _)) -> do
       cID <- encrypt sId
       $logDebugS "sinkMultiSubmission" $ "Feeding rating for " <> toPathPiece cID
@@ -586,7 +579,7 @@ sinkMultiSubmission userId isUpdate = do
           cID <- encrypt sId
           handle (throwM . SubmissionSinkException cID (Just fileTitle)) $
             lift . feed sId $ Left f{ fileTitle = fileTitle' }
-  when (not $ null ignored) $ do
+  when (not $ null ignoredFiles) $ do
     mr <- (toHtml .) <$> getMessageRender
     addMessage Warning =<< withUrlRenderer ($(ihamletFile "templates/messages/submissionFilesIgnored.hamlet") mr)
   lift . fmap Set.fromList . forM (Map.toList sinks) $ \(sId, sink) -> do
diff --git a/src/Handler/Utils/Table/Pagination.hs b/src/Handler/Utils/Table/Pagination.hs
index f36fba523..550aca3ca 100644
--- a/src/Handler/Utils/Table/Pagination.hs
+++ b/src/Handler/Utils/Table/Pagination.hs
@@ -27,13 +27,10 @@ module Handler.Utils.Table.Pagination
 import Handler.Utils.Table.Pagination.Types
 import Utils.Lens.TH
 
-import Import
+import Import hiding (pi)
 import qualified Database.Esqueleto as E
 import qualified Database.Esqueleto.Internal.Sql as E (SqlSelect,unsafeSqlValue)
 import qualified Database.Esqueleto.Internal.Language as E (From)
-import Text.Blaze (Attribute)
-import qualified Text.Blaze.Html5.Attributes as Html5
-import qualified Text.Blaze.Html5 as Html5
 
 import qualified Data.Binary.Builder as Builder
 
@@ -42,8 +39,8 @@ import qualified Network.Wai as Wai
 import Data.CaseInsensitive (CI)
 import qualified Data.CaseInsensitive as CI
 
-import Control.Monad.RWS hiding ((<>), Foldable(..), mapM_, forM_)
-import Control.Monad.Writer hiding ((<>), Foldable(..), mapM_, forM_)
+import Control.Monad.RWS hiding ((<>), mapM_, forM_)
+import Control.Monad.Writer hiding ((<>), mapM_, forM_)
 import Control.Monad.Reader (ReaderT(..), mapReaderT)
 import Control.Monad.Trans.Maybe
 
@@ -52,8 +49,6 @@ import Data.Foldable (Foldable(foldMap))
 import Data.Map (Map, (!))
 import qualified Data.Map as Map
 
-import Data.Profunctor (lmap)
-
 import Colonnade hiding (bool, fromMaybe, singleton)
 import qualified Colonnade (singleton)
 import Colonnade.Encode
@@ -64,8 +59,6 @@ import Data.Ratio ((%))
 
 import Control.Lens
 
-import Data.Proxy
-
 
 data SortColumn t = forall a. PersistField a => SortColumn { getSortColumn :: t -> E.SqlExpr (E.Value a) }
 
@@ -103,9 +96,9 @@ instance {-# OVERLAPPABLE #-} (PathPiece (Element l), IsFilterColumn t cont, Mon
     where
       (input, ($ []) -> is') = go (mempty, id) is
       go acc [] = acc
-      go (acc, is') (i:is)
-        | Just i' <- fromPathPiece i = go (acc `mappend` singleton i', is') is
-        | otherwise = go (acc, is' . (i:)) is
+      go (acc, is3) (i:is2)
+        | Just i' <- fromPathPiece i = go (acc `mappend` singleton i', is3) is2
+        | otherwise = go (acc, is3 . (i:)) is2
 
 data PaginationSettings = PaginationSettings
   { psSorting      :: [(CI Text, SortDirection)]
@@ -181,26 +174,26 @@ instance Default (PSValidator m x) where
       asks piShortcircuit >>= (\s -> modify $ \ps -> ps { psShortcircuit = s })
 
 defaultFilter :: Map (CI Text) [Text] -> PSValidator m x -> PSValidator m x
-defaultFilter psFilter (runPSValidator -> f) = PSValidator $ \dbTable -> injectDefault <*> f dbTable
+defaultFilter psFilter (runPSValidator -> f) = PSValidator $ \dbTable' -> injectDefault <*> f dbTable'
   where
     injectDefault x = case x >>= piFilter of
       Just _  -> id
       Nothing -> set (_2._psFilter) psFilter
 
 defaultSorting :: [(CI Text, SortDirection)] -> PSValidator m x -> PSValidator m x
-defaultSorting psSorting (runPSValidator -> f) = PSValidator $ \dbTable -> injectDefault <*> f dbTable
+defaultSorting psSorting (runPSValidator -> f) = PSValidator $ \dbTable' -> injectDefault <*> f dbTable'
   where
     injectDefault x = case x >>= piSorting of
       Just _  -> id
       Nothing -> set (_2._psSorting) psSorting
 
 restrictFilter :: (CI Text -> [Text] -> Bool) -> PSValidator m x -> PSValidator m x
-restrictFilter restrict (runPSValidator -> f) = PSValidator $ \dbTable ps -> over _2 restrict' $ f dbTable ps
+restrictFilter restrict (runPSValidator -> f) = PSValidator $ \dbTable' ps -> over _2 restrict' $ f dbTable' ps
   where
     restrict' p = p { psFilter = Map.filterWithKey restrict $ psFilter p }
 
 restrictSorting :: (CI Text -> SortDirection -> Bool) -> PSValidator m x -> PSValidator m x
-restrictSorting restrict (runPSValidator -> f) = PSValidator $ \dbTable ps -> over _2 restrict' $ f dbTable ps
+restrictSorting restrict (runPSValidator -> f) = PSValidator $ \dbTable' ps -> over _2 restrict' $ f dbTable' ps
   where
     restrict' p = p { psSorting = filter (uncurry restrict) $ psSorting p }
 
@@ -319,8 +312,8 @@ instance Monoid a => IsDBTable (RWST (Maybe (Env, FileEnv), UniWorX, [Lang]) Enc
   
   -- dbWidget Proxy Proxy = iso ((,) <$> view (_1._2) <*> ((,) <$> view (_1._1) <*> view _2))
   --                            ((,) <$> ((,) <$> view (_2._1) <*> view _1) <*> view (_2._2))
-  dbWidget DBTable{ dbtIdent = (toPathPiece -> dbtIdent) } = liftHandlerT . fmap (view $ _1 . _2) . runFormPost
-  dbHandler DBTable{ dbtIdent = (toPathPiece -> dbtIdent) } f form = return $ \csrf -> over _2 f <$> form csrf
+  dbWidget _ = liftHandlerT . fmap (view $ _1 . _2) . runFormPost
+  dbHandler _ f form = return $ \csrf -> over _2 f <$> form csrf
   -- runDBTable :: MForm (HandlerT UniWorX IO) (FormResult a, Widget) -> m ((FormResult a, Widget), Enctype)
   -- runDBTable form = liftHandlerT . runFormPost $ \html -> over _2 (<> toWidget html) <$> form
   -- runDBTable :: MForm (HandlerT UniWorX IO) (FormResult a, Widget) -> m (Html -> MForm (HandleT UniWorX IO) (FormResult a, Widget))
@@ -343,7 +336,6 @@ dbTable PSValidator{..} dbtable@(DBTable{ dbtIdent = (toPathPiece -> dbtIdent),
       , d <- [SortAsc, SortDesc]
       , let t' = CI.foldedCase t <> "-" <> toPathPiece d
       ]
-    (_, defPS) = runPSValidator dbtable Nothing
     wIdent n
       | not $ null dbtIdent = dbtIdent <> "-" <> n
       | otherwise           = n
@@ -352,7 +344,7 @@ dbTable PSValidator{..} dbtable@(DBTable{ dbtIdent = (toPathPiece -> dbtIdent),
       | otherwise           = dbsAttrs
     multiTextField = Field
       { fieldParse = \ts _ -> return . Right $ Just ts
-      , fieldView = undefined
+      , fieldView = error "multiTextField: should not be rendered"
       , fieldEnctype = UrlEncoded
       }
     
@@ -373,7 +365,7 @@ dbTable PSValidator{..} dbtable@(DBTable{ dbtIdent = (toPathPiece -> dbtIdent),
     (errs, PaginationSettings{..}) = case psResult of
       FormSuccess pi
         | not (piIsUnset pi) -> runPSValidator dbtable $ Just pi
-      FormFailure errs       -> first (map SomeMessage errs <>) $ runPSValidator dbtable Nothing
+      FormFailure errs'      -> first (map SomeMessage errs' <>) $ runPSValidator dbtable Nothing
       _                      -> runPSValidator dbtable Nothing
     psSorting' = map (first (dbtSorting !)) psSorting
     sqlQuery' = E.from $ \t -> dbtSQLQuery t
@@ -417,9 +409,9 @@ dbTable PSValidator{..} dbtable@(DBTable{ dbtIdent = (toPathPiece -> dbtIdent),
 
         wHeaders <- maybe (return Nothing) (fmap Just . genHeaders) pSortable
 
-        wRows <- forM rows $ \row -> forM (oneColonnadeEncode <$> getColonnade dbtColonnade) $ \(($ row) -> cell) -> do
-          widget <- cell ^. cellContents
-          let attrs = cell ^. cellAttrs
+        wRows <- forM rows $ \row' -> forM (oneColonnadeEncode <$> getColonnade dbtColonnade) $ \(($ row') -> cell') -> do
+          widget <- cell' ^. cellContents
+          let attrs = cell' ^. cellAttrs
           return $(widgetFile "table/cell/body")
       
         let table = $(widgetFile "table/colonnade")
@@ -480,7 +472,7 @@ tickmarkCell True  = textCell (tickmark :: Text)
 tickmarkCell False = mempty
 
 cellTooltip :: (RenderMessage UniWorX msg, IsDBTable m a) => msg -> DBCell m a -> DBCell m a
-cellTooltip msg cell = cell & cellContents.mapped %~ (<> tipWdgt)
+cellTooltip msg = cellContents.mapped %~ (<> tipWdgt)
   where
     tipWdgt = [whamlet|
         <div .js-tooltip>
diff --git a/src/Handler/Utils/Templates.hs b/src/Handler/Utils/Templates.hs
index bdd82db86..14f8ce38c 100644
--- a/src/Handler/Utils/Templates.hs
+++ b/src/Handler/Utils/Templates.hs
@@ -14,5 +14,5 @@ modal modalTrigger modalContent = do
   triggerId <- newIdent
   $(widgetFile "widgets/modal")
   case modalContent of
-    Left route -> [whamlet|<a .btn ##{triggerId} href=@{route}>^{modalTrigger}|]
-    Right content -> [whamlet|<div .btn ##{triggerId}>^{modalTrigger}|]
+    Left  route -> [whamlet|<a .btn ##{triggerId} href=@{route}>^{modalTrigger}|]
+    Right _     -> [whamlet|<div .btn ##{triggerId}>^{modalTrigger}|]
diff --git a/src/Jobs.hs b/src/Jobs.hs
index e3b4b0276..50bb56e5d 100644
--- a/src/Jobs.hs
+++ b/src/Jobs.hs
@@ -34,16 +34,15 @@ import Data.HashMap.Strict (HashMap)
 
 import qualified Data.List.NonEmpty as NonEmpty
 
-import Data.Map.Strict (Map)
 import qualified Data.Map.Strict as Map
 
 import Data.Foldable (foldrM)
 
 import Control.Monad.Trans.Reader (mapReaderT)
-import Control.Monad.Trans.State (StateT, evalStateT, mapStateT)
+import Control.Monad.Trans.State (evalStateT, mapStateT)
 import qualified Control.Monad.State.Class as State
 import Control.Monad.Reader.Class (MonadReader(..))
-import Control.Monad.Trans.Resource (MonadResourceBase, ResourceT, runResourceT, allocate, release)
+import Control.Monad.Trans.Resource (MonadResourceBase, runResourceT, allocate, release)
 import Control.Monad.Trans.Maybe (MaybeT(..))
 import Control.Monad.Logger
 
@@ -134,7 +133,7 @@ execCrontab = evalStateT go HashMap.empty
             | otherwise = lift $ delete leId
         runConduit $ transPipe lift (selectSource [] []) .| C.mapM_ merge
 
-      now <- liftIO getCurrentTime
+      refT <- liftIO getCurrentTime
       currentState <- mapStateT (mapReaderT $ liftIO . atomically) $ do
         crontab' <- liftBase . tryReadTMVar =<< asks jobCrontab
         case crontab' of
@@ -142,7 +141,7 @@ execCrontab = evalStateT go HashMap.empty
           Just crontab -> Just <$> do
             State.modify . HashMap.filterWithKey $ \k _ -> HashMap.member k crontab
             prevExec <- State.get
-            case earliestJob prevExec crontab now of
+            case earliestJob prevExec crontab refT of
               Nothing -> liftBase retry
               Just (_, MatchNone) -> liftBase retry
               Just x -> return (crontab, x)
@@ -160,7 +159,7 @@ execCrontab = evalStateT go HashMap.empty
                         State.modify $ HashMap.alter (Just . ($ Max now) . maybe id (<>)) jobCtl
                         case jobCtl of
                           JobCtlQueue job -> do
-                            lift . lift $ upsertBy
+                            void . lift . lift $ upsertBy
                               (UniqueCronLastExec $ toJSON job)
                               CronLastExec
                                 { cronLastExecJob = toJSON job
diff --git a/src/Jobs/Handler/HelpRequest.hs b/src/Jobs/Handler/HelpRequest.hs
index 73642e90b..d1f98d5ad 100644
--- a/src/Jobs/Handler/HelpRequest.hs
+++ b/src/Jobs/Handler/HelpRequest.hs
@@ -2,7 +2,7 @@ module Jobs.Handler.HelpRequest
   ( dispatchJobHelpRequest
   ) where
 
-import Import hiding ((.=))
+import Import
 
 import Text.Hamlet
 import qualified Data.CaseInsensitive as CI
diff --git a/src/Jobs/Handler/SendNotification/CorrectionsAssigned.hs b/src/Jobs/Handler/SendNotification/CorrectionsAssigned.hs
index 15f7a0289..dd4987437 100644
--- a/src/Jobs/Handler/SendNotification/CorrectionsAssigned.hs
+++ b/src/Jobs/Handler/SendNotification/CorrectionsAssigned.hs
@@ -1,10 +1,11 @@
+{-# OPTIONS_GHC -fno-warn-unused-do-bind #-} -- ihamletFile discards do results
+
 module Jobs.Handler.SendNotification.CorrectionsAssigned
   ( dispatchNotificationCorrectionsAssigned
   ) where
 
 import Import
 
-import Utils.Lens
 import Handler.Utils.Mail
 
 import Text.Hamlet
@@ -25,10 +26,6 @@ dispatchNotificationCorrectionsAssigned  nUser nSheet jRecipient = do
 
     MsgRenderer mr <- getMailMsgRenderer
     let termDesc = mr . ShortTermIdentifier $ unTermKey courseTerm
-        tid = courseTerm
-        ssh = courseSchool
-        csh = courseShorthand
-        shn = sheetName
 
     addAlternatives $ do
       let editNotifications = $(ihamletFile "templates/mail/editNotifications.hamlet")
diff --git a/src/Jobs/Handler/SendNotification/SheetActive.hs b/src/Jobs/Handler/SendNotification/SheetActive.hs
index 0de2ff787..91a8fc716 100644
--- a/src/Jobs/Handler/SendNotification/SheetActive.hs
+++ b/src/Jobs/Handler/SendNotification/SheetActive.hs
@@ -1,10 +1,11 @@
+{-# OPTIONS_GHC -fno-warn-unused-do-bind #-} -- ihamletFile discards do results
+
 module Jobs.Handler.SendNotification.SheetActive
   ( dispatchNotificationSheetActive
   ) where
 
 import Import
 
-import Utils.Lens
 import Handler.Utils.Mail
 
 import Text.Hamlet
diff --git a/src/Jobs/Handler/SendNotification/SheetInactive.hs b/src/Jobs/Handler/SendNotification/SheetInactive.hs
index 99248e777..f318539f4 100644
--- a/src/Jobs/Handler/SendNotification/SheetInactive.hs
+++ b/src/Jobs/Handler/SendNotification/SheetInactive.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-unused-do-bind #-} -- ihamletFile discards do results
+
 module Jobs.Handler.SendNotification.SheetInactive
   ( dispatchNotificationSheetSoonInactive
   , dispatchNotificationSheetInactive
@@ -5,7 +7,6 @@ module Jobs.Handler.SendNotification.SheetInactive
 
 import Import
 
-import Utils.Lens
 import Handler.Utils.Mail
 
 import Text.Hamlet
diff --git a/src/Jobs/Handler/SendNotification/SubmissionRated.hs b/src/Jobs/Handler/SendNotification/SubmissionRated.hs
index 204ac5392..4e4f403c5 100644
--- a/src/Jobs/Handler/SendNotification/SubmissionRated.hs
+++ b/src/Jobs/Handler/SendNotification/SubmissionRated.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-unused-do-bind #-} -- ihamletFile discards do results
+
 module Jobs.Handler.SendNotification.SubmissionRated
   ( dispatchNotificationSubmissionRated
   ) where
diff --git a/src/Jobs/Queue.hs b/src/Jobs/Queue.hs
index bc9ab4fee..001471544 100644
--- a/src/Jobs/Queue.hs
+++ b/src/Jobs/Queue.hs
@@ -17,7 +17,6 @@ import Control.Monad.Trans.Reader (ReaderT, mapReaderT)
 import qualified Data.Set as Set
 import qualified Data.List.NonEmpty as NonEmpty
 import qualified Data.HashMap.Strict as HashMap
-import qualified Data.Map.Strict as Map
 
 import Control.Monad.Random (evalRand, mkStdGen, uniform)
 
diff --git a/src/Mail.hs b/src/Mail.hs
index cbbc1c933..1d83e7d1c 100644
--- a/src/Mail.hs
+++ b/src/Mail.hs
@@ -32,14 +32,13 @@ module Mail
   ) where
 
 import ClassyPrelude.Yesod hiding (snoc, (.=), getMessageRender)
-import qualified ClassyPrelude.Yesod as Yesod (getMessageRender)
 
 import Network.Mail.Mime hiding (addPart, addAttachment)
 import qualified Network.Mail.Mime as Mime (addPart)
 
 import Data.Monoid (Last(..))
-import Control.Monad.Trans.RWS (RWST(..), execRWST)
-import Control.Monad.Trans.State (StateT(..), execStateT, State, mapStateT)
+import Control.Monad.Trans.RWS (RWST(..))
+import Control.Monad.Trans.State (StateT(..), execStateT, mapStateT)
 import Control.Monad.Trans.Writer (execWriter, Writer)
 import Control.Monad.RWS.Class (MonadWriter(..), MonadReader(..), MonadState(..), modify)
 import Control.Monad.Fail
@@ -50,8 +49,6 @@ import Generics.Deriving.Monoid (memptydefault, mappenddefault)
 import Data.Sequence (Seq)
 import qualified Data.Sequence as Seq
 
-import Data.Data (Data)
-
 import Data.Set (Set)
 import qualified Data.Set as Set
 
@@ -59,15 +56,13 @@ import qualified Data.Text as Text
 
 import qualified Data.Foldable as Foldable
 
-import Data.Hashable
-
 import qualified Data.Text.Lazy as LT
 import qualified Data.Text.Lazy.Builder as LTB
 import qualified Data.ByteString.Lazy as LBS
 
 import Utils (MsgRendererS(..))
 import Utils.Lens.TH
-import Control.Lens
+import Control.Lens hiding (from)
 
 import Text.Blaze.Renderer.Utf8
 
@@ -84,7 +79,6 @@ import Network.BSD (getHostName)
 
 import Data.Time.Zones (TZ, utcTZ, utcToLocalTimeTZ, timeZoneForUTCTime)
 import Data.Time.LocalTime (ZonedTime(..))
-import Data.Time.Format
 
 import Network.HaskellNet.SMTP (SMTPConnection)
 import qualified Network.HaskellNet.SMTP as SMTP
@@ -96,7 +90,6 @@ import qualified Data.Aeson as Aeson
 import qualified Data.Aeson.Encode.Pretty as Aeson
 import Data.Aeson (Options(..))
 import Data.Aeson.TH
-import Utils (MsgRendererS(..))
 import Utils.PathPiece (splitCamel)
 import Utils.DateTime
 
@@ -108,7 +101,7 @@ makeLenses_ ''Mail
 makeLenses_ ''Part
 
 
-newtype MailT m a = MailT { unMailT :: RWST MailContext MailSmtpData Mail m a }
+newtype MailT m a = MailT { _unMailT :: RWST MailContext MailSmtpData Mail m a }
   deriving newtype ( MonadTrans, Monad, Functor, MonadFail, Applicative, Alternative, MonadPlus
                    , MonadIO, MonadHandler, MonadCatch, MonadThrow, MonadMask, MonadResource, MonadBase b
                    , MonadState Mail, MonadWriter MailSmtpData, MonadReader MailContext
@@ -250,11 +243,11 @@ defMailT :: ( MonadHandler m
             ) => MailContext
               -> MailT m a
               -> m a
-defMailT ls (MailT mail) = do
+defMailT ls (MailT mailC) = do
   fromAddress <- defaultFromAddress
-  (ret, mail, smtpData) <- runRWST mail ls (emptyMail fromAddress)
+  (ret, mail, smtpData) <- runRWST mailC ls (emptyMail fromAddress)
   mail' <- liftIO $ LBS.toStrict <$> renderMail' mail
-  $logDebugS "Mail" $ "Rendered mail:\n" <> decodeUtf8 mail'
+  -- $logDebugS "Mail" $ "Rendered mail:\n" <> decodeUtf8 mail'
   ret <$ case smtpData of
     MailSmtpData{ smtpEnvelopeFrom = Last Nothing } -> throwM MailNoSenderSpecified
     MailSmtpData{ smtpRecipients }
@@ -457,12 +450,13 @@ setMailSmtpData = do
   if
     | Verp{..} <- verpMode
     , [recp] <- Set.toList recps
-    -> let doVerp (Text.breakOn "@" -> (user, domain)) recp = mconcat
+    -> let (user, domain) = Text.breakOn "@" from
+           verp = mconcat
              [ user
              , Text.singleton verpSeparator
              , Text.replace "@" (Text.singleton verpAtReplacement) recp
              , domain
              ]
-        in tell $ mempty { smtpEnvelopeFrom = Last . Just $ doVerp from recp }
+        in tell $ mempty { smtpEnvelopeFrom = Last $ Just verp }
     | otherwise
     -> tell $ mempty { smtpEnvelopeFrom = Last $ Just from }
diff --git a/src/Model.hs b/src/Model.hs
index 15da993f1..91de5c48c 100644
--- a/src/Model.hs
+++ b/src/Model.hs
@@ -14,7 +14,6 @@ import Model.Types
 import Cron.Types
 
 import Data.Aeson (Value)
-import Data.Aeson.TH (deriveJSON, defaultOptions)
 
 import Data.CaseInsensitive (CI)
 import Data.CaseInsensitive.Instances ()
@@ -31,6 +30,7 @@ share [mkPersist sqlSettings, mkDeleteCascade sqlSettings, mkMigrate "migrateAll
 
 -- (Eq Course) is impossible so we derive it for the Uniqueness Constraint only
 deriving instance Eq (Unique Course)
+deriving instance Eq (Unique Sheet)
 
 submissionRatingDone :: Submission -> Bool
 submissionRatingDone Submission{..} = isJust submissionRatingTime
diff --git a/src/Model/Migration/Types.hs b/src/Model/Migration/Types.hs
index c3885f3ff..f3bac96b6 100644
--- a/src/Model/Migration/Types.hs
+++ b/src/Model/Migration/Types.hs
@@ -1,11 +1,7 @@
 module Model.Migration.Types where 
 
 import ClassyPrelude.Yesod hiding  (derivePersistFieldJSON)
-import qualified Data.Aeson as Aeson
-import qualified Data.Aeson.Types as Aeson
-import Data.Aeson (FromJSON(..), ToJSON(..), FromJSONKey(..), ToJSONKey(..), FromJSONKeyFunction(..), withText, withObject, Value())
-import Data.Aeson.Types (toJSONKeyText)
-import Data.Aeson.TH (deriveJSON, defaultOptions, Options(..), SumEncoding(..))
+import Data.Aeson.TH (deriveJSON, defaultOptions)
 import Database.Persist.Sql
 
 import qualified Model as Current
@@ -30,4 +26,4 @@ sheetType NotGraded   = Current.NotGraded
 
 
 deriveJSON defaultOptions ''SheetType
-Current.derivePersistFieldJSON ''SheetType
\ No newline at end of file
+Current.derivePersistFieldJSON ''SheetType
diff --git a/src/Model/Types/JSON.hs b/src/Model/Types/JSON.hs
index 4e2927edb..e69f8f1b2 100644
--- a/src/Model/Types/JSON.hs
+++ b/src/Model/Types/JSON.hs
@@ -16,10 +16,10 @@ import Language.Haskell.TH.Datatype
 
 
 derivePersistFieldJSON :: Name -> DecsQ
-derivePersistFieldJSON n = do
-  DatatypeInfo{..} <- reifyDatatype n
+derivePersistFieldJSON tName = do
+  DatatypeInfo{..} <- reifyDatatype tName
   vars <- forM datatypeVars (const $ newName "a")
-  let t = foldl (\t n -> t `appT` varT n) (conT n) vars
+  let t = foldl (\t' n' -> t' `appT` varT n') (conT tName) vars
       iCxt
         | null vars = cxt []
         | otherwise = cxt [[t|ToJSON|] `appT` t, [t|FromJSON|] `appT` t]
@@ -39,8 +39,8 @@ derivePersistFieldJSON n = do
             bs <- newName "bs"
             clause [[p|PersistByteString $(varP bs)|]] (normalB [e|first pack $ JSON.eitherDecodeStrict' $(varE bs)|]) []
         , do
-            t <- newName "t"
-            clause [[p|PersistText $(varP t)|]] (normalB [e|first pack . JSON.eitherDecodeStrict' $ Text.encodeUtf8 $(varE t)|]) []
+            text <- newName "text"
+            clause [[p|PersistText $(varP text)|]] (normalB [e|first pack . JSON.eitherDecodeStrict' $ Text.encodeUtf8 $(varE text)|]) []
         , clause [wildP] (normalB [e|Left "JSON values must be converted from PersistDbSpecific, PersistText, or PersistByteString"|]) []
         ]
       ]
diff --git a/src/Utils/Lens.hs b/src/Utils/Lens.hs
index 00b2e77d6..46a2a5344 100644
--- a/src/Utils/Lens.hs
+++ b/src/Utils/Lens.hs
@@ -2,7 +2,7 @@ module Utils.Lens ( module Utils.Lens ) where
 
 import Import.NoFoundation
 import Control.Lens as Utils.Lens
-import Utils.Lens.TH
+import Utils.Lens.TH as Utils.Lens (makeLenses_)
 
 import qualified Database.Esqueleto as E (Value(..),InnerJoin(..))
 
diff --git a/templates/correction-user.hamlet b/templates/correction-user.hamlet
index 8c0b21a71..0a639bf81 100644
--- a/templates/correction-user.hamlet
+++ b/templates/correction-user.hamlet
@@ -3,7 +3,7 @@
     <tr .table__row>
       <th .table__th>_{MsgSubmission}
       <td .table__td>#{display cid}
-    $maybe Entity _ User{..} <- corrector
+    $maybe Entity _ User{userDisplayName} <- corrector
       <tr .table__row>
         <th .table__th>_{MsgRatingBy}
         <td .table__td>#{display userDisplayName}
diff --git a/templates/default-layout.hamlet b/templates/default-layout.hamlet
index 63ecb972a..f9f4bb3cb 100644
--- a/templates/default-layout.hamlet
+++ b/templates/default-layout.hamlet
@@ -10,7 +10,7 @@
 
     <!-- breadcrumbs -->
     $if not $ Just HomeR == mcurrentRoute
-      ^{breadcrumbs}
+      ^{breadcrumbsWgt}
 
     <div .main__content-body>
 
diff --git a/templates/login.hamlet b/templates/login.hamlet
index f3cf5ece8..f39c36e64 100644
--- a/templates/login.hamlet
+++ b/templates/login.hamlet
@@ -1,4 +1,4 @@
-$forall AuthPlugin{..} <- plugins
+$forall AuthPlugin{apName, apLogin} <- plugins
   $if apName == "LDAP"
     <section>
       <h2>_{MsgLDAPLoginTitle}
diff --git a/templates/mail/submissionRated.hamlet b/templates/mail/submissionRated.hamlet
index 77b7ba80c..63afe4ee5 100644
--- a/templates/mail/submissionRated.hamlet
+++ b/templates/mail/submissionRated.hamlet
@@ -23,7 +23,7 @@ $newline never
       <dd>
         <a href=@{CSubmissionR tid ssh csh shn csid SubShowR}>
           #{display csid}
-      $maybe User{..} <- corrector
+      $maybe User{userDisplayName} <- corrector
         <dt>
           _{MsgRatingBy}
         <dd>
diff --git a/templates/mail/support.hamlet b/templates/mail/support.hamlet
index 43555df6f..1b3d7e1f7 100644
--- a/templates/mail/support.hamlet
+++ b/templates/mail/support.hamlet
@@ -12,7 +12,7 @@ $newline never
         $of Left  Nothing
         $of Right Nothing
           <dt>Ungültige UserId erhalten!
-        $of Right (Just (Entity _ User{..}))
+        $of Right (Just (Entity _ User{userDisplayName, userSurname, userIdent, userEmail, userMatrikelnummer, userMailLanguages}))
           <dt>Name
           <dd>^{const (const (nameHtml userDisplayName userSurname))}
           <dt>Identifikation
diff --git a/templates/messages/submissionFilesIgnored.hamlet b/templates/messages/submissionFilesIgnored.hamlet
index f02bed623..ebb61695e 100644
--- a/templates/messages/submissionFilesIgnored.hamlet
+++ b/templates/messages/submissionFilesIgnored.hamlet
@@ -1,6 +1,6 @@
 _{MsgSubmissionFilesIgnored}
 <ul>
-  $forall ident <- ignored
+  $forall ident <- ignoredFiles
     $case ident
       $of Right fileTitle
         <li style="font-family: monospace">#{fileTitle}
diff --git a/templates/widgets/asidenav.hamlet b/templates/widgets/asidenav.hamlet
index f75a8f162..bb5f41407 100644
--- a/templates/widgets/asidenav.hamlet
+++ b/templates/widgets/asidenav.hamlet
@@ -1,16 +1,12 @@
 $newline never
 <aside .main__aside>
   <div .asidenav>
-    $forall tid@TermIdentifier{..} <- favouriteTerms
+    $forall tid <- favouriteTerms
       <div .asidenav__box.js-show-hide>
-        <h3 .asidenav__box-title.js-show-hide__toggle data-sh-index="#{display season}-#{year}">
-          $case season
-            $of Winter
-              _{MsgWinterTermShort year}
-            $of Summer
-              _{MsgSummerTermShort year}
+        <h3 .asidenav__box-title.js-show-hide__toggle data-sh-index="#{termToText tid}">
+          _{ShortTermIdentifier tid}
         <ul .asidenav__list.js-show-hide__target.list--iconless>
-          $forall (Course{..}, courseRoute, pageActions) <- favouriteTerm tid
+          $forall (Course{courseShorthand, courseName}, courseRoute, pageActions) <- favouriteTerm tid
             <li .asidenav__list-item :highlight courseRoute:.asidenav__list-item--active>
               <a .asidenav__link-wrapper href=@{courseRoute}>
                 <div .asidenav__link-shorthand>#{courseShorthand}
@@ -18,7 +14,7 @@ $newline never
               <ul .asidenav__nested-list.list--iconless>
                 $forall action <- pageActions
                   $case action
-                    $of PageActionPrime (MenuItem{..})
+                    $of PageActionPrime (MenuItem{menuItemRoute, menuItemLabel})
                       <li .asidenav__nested-list-item>
                         <a .asidenav__link-wrapper href=@{menuItemRoute}>#{menuItemLabel}
                     $of _
diff --git a/templates/widgets/rating.hamlet b/templates/widgets/rating.hamlet
index 2b3d021e1..d9241e561 100644
--- a/templates/widgets/rating.hamlet
+++ b/templates/widgets/rating.hamlet
@@ -6,7 +6,7 @@ $maybe points <- submissionRatingPoints
     $case grading	
       $of Points{..}
         _{MsgAchievedOf points maxPoints}          
-      $of PassPoints{..}
+      $of PassPoints{}
         $if fromMaybe False (gradingPassed grading points)
           _{MsgPassed}
         $else