diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# happstack-server [![Hackage Status](https://img.shields.io/hackage/v/happstack-server.svg)][hackage] [![Build Status](https://travis-ci.com/Happstack/happstack-server.svg?branch=master)](https://travis-ci.com/Happstack/happstack-server)
+# happstack-server [![Hackage Status](https://img.shields.io/hackage/v/happstack-server.svg)][hackage]
 
 [hackage]: https://hackage.haskell.org/package/happstack-server
 
diff --git a/happstack-server.cabal b/happstack-server.cabal
--- a/happstack-server.cabal
+++ b/happstack-server.cabal
@@ -1,5 +1,5 @@
 Name:                happstack-server
-Version:             7.7.2
+Version:             7.8.0
 Synopsis:            Web related tools and services.
 Description:         Happstack Server provides an HTTP server and a rich set of functions for routing requests, handling query parameters, generating responses, working with cookies, serving files, and more. For in-depth documentation see the Happstack Crash Course <http://happstack.com/docs/crashcourse/index.html>
 License:             BSD3
@@ -11,7 +11,7 @@
 Build-Type:          Simple
 Cabal-Version:       >= 1.10
 Extra-Source-Files:  tests/Happstack/Server/Tests.hs README.md
-tested-with:         GHC==8.0.1, GHC==8.2.2, GHC==8.4.1, GHC==8.6.5, GHC==8.8.3, GHC==8.10.1, GHC==9.0.1
+tested-with:         GHC==8.0.2, GHC==8.2.2, GHC==8.4.4, GHC==8.6.5, GHC==8.8.4, GHC==8.10.7, GHC==9.0.2, GHC==9.2.2
 
 source-repository head
     type:     git
@@ -77,8 +77,8 @@
                        filepath,
                        hslogger               >= 1.0.2,
                        html,
-                       monad-control          >= 0.3  && < 1.1,
-                       mtl                    >= 2    && < 2.3,
+                       monad-control          >= 1.0  && < 1.1,
+                       mtl                    >= 2.2  && < 2.4,
                        old-locale,
                        parsec                            < 4,
                        process,
diff --git a/src/Happstack/Server/Error.hs b/src/Happstack/Server/Error.hs
--- a/src/Happstack/Server/Error.hs
+++ b/src/Happstack/Server/Error.hs
@@ -1,7 +1,7 @@
 -- | Some useful functions if you want to wrap the 'ServerPartT' monad transformer around the 'ErrorT' monad transformer. e.g., @'ServerPartT' ('ErrorT' e m) a@. This allows you to use 'throwError' and 'catchError' inside your monad.  
 module Happstack.Server.Error where
 
-import Control.Monad.Error              (Error, ErrorT(runErrorT))
+import Control.Monad.Trans.Except       (ExceptT, runExceptT)
 import Happstack.Server.Monads          (ServerPartT)
 import Happstack.Server.Internal.Monads (WebT, UnWebT, withRequest, mkWebT, runServerPartT, ununWebT)
 import Happstack.Server.Response        (ok, toResponse)
@@ -22,10 +22,10 @@
 -- see also: 'simpleErrorHandler'
 spUnwrapErrorT:: Monad m => (e -> ServerPartT m a)
               -> Request
-              -> UnWebT (ErrorT e m) a
+              -> UnWebT (ExceptT e m) a
               -> UnWebT m a
 spUnwrapErrorT handler rq = \x -> do
-    err <- runErrorT x
+    err <- runExceptT x
     case err of
         Left e -> ununWebT $ runServerPartT (handler e) rq
         Right a -> return a
@@ -48,9 +48,9 @@
 -- function.
 --
 -- DEPRECATED: use 'spUnwrapErrorT' instead.
-errorHandlerSP :: (Monad m, Error e) => (Request -> e -> WebT m a) -> ServerPartT (ErrorT e m) a -> ServerPartT m a
+errorHandlerSP :: (Monad m) => (Request -> e -> WebT m a) -> ServerPartT (ExceptT e m) a -> ServerPartT m a
 errorHandlerSP handler sps = withRequest $ \req -> mkWebT $ do
-                        eer <- runErrorT $ ununWebT $ runServerPartT sps req
+                        eer <- runExceptT $ ununWebT $ runServerPartT sps req
                         case eer of
                                 Left err -> ununWebT (handler req err)
                                 Right res -> return res
diff --git a/src/Happstack/Server/Internal/Monads.hs b/src/Happstack/Server/Internal/Monads.hs
--- a/src/Happstack/Server/Internal/Monads.hs
+++ b/src/Happstack/Server/Internal/Monads.hs
@@ -12,9 +12,11 @@
                                                  )
 import Control.Monad.Base                        ( MonadBase, liftBase )
 import Control.Monad.Catch                       ( MonadCatch(..), MonadThrow(..) )
-import Control.Monad.Error                       ( ErrorT(ErrorT), runErrorT
-                                                 , Error, MonadError, throwError
-                                                 , catchError, mapErrorT
+#if !MIN_VERSION_mtl(2,3,0)
+import Control.Monad.Error                       ( ErrorT, Error, mapErrorT )
+#endif
+import Control.Monad.Except                      ( MonadError, throwError
+                                                 , catchError
                                                  )
 #if MIN_VERSION_base(4,9,0)
 import Control.Monad.Fail                        (MonadFail)
@@ -26,7 +28,7 @@
 import qualified Control.Monad.RWS.Lazy as Lazy       ( RWST, mapRWST )
 import qualified Control.Monad.RWS.Strict as Strict   ( RWST, mapRWST )
 
-import Control.Monad.Trans.Except                ( ExceptT, mapExceptT )
+import Control.Monad.Trans.Except                ( ExceptT(ExceptT), mapExceptT, runExceptT )
 import Control.Monad.State.Class                      ( MonadState, get, put )
 import qualified Control.Monad.State.Lazy as Lazy     ( StateT, mapStateT )
 import qualified Control.Monad.State.Strict as Strict ( StateT, mapStateT )
@@ -93,7 +95,6 @@
     liftIO = ServerPartT . liftIO
     {-# INLINE liftIO #-}
 
-#if MIN_VERSION_monad_control(1,0,0)
 instance MonadTransControl ServerPartT where
     type StT ServerPartT a = StT WebT (StT (ReaderT Request) a)
     liftWith f = ServerPartT $ liftWith $ \runReader ->
@@ -105,20 +106,7 @@
     type StM (ServerPartT m) a = ComposeSt ServerPartT m a
     liftBaseWith = defaultLiftBaseWith
     restoreM     = defaultRestoreM
-#else
-instance MonadTransControl ServerPartT where
-    newtype StT ServerPartT a = StSP {unStSP :: StT WebT (StT (ReaderT Request) a)}
-    liftWith f = ServerPartT $ liftWith $ \runReader ->
-                                 liftWith $ \runWeb ->
-                                   f $ liftM StSP . runWeb . runReader . unServerPartT
-    restoreT = ServerPartT . restoreT . restoreT . liftM unStSP
 
-instance MonadBaseControl b m => MonadBaseControl b (ServerPartT m) where
-    newtype StM (ServerPartT m) a = StMSP {unStMSP :: ComposeSt ServerPartT m a}
-    liftBaseWith = defaultLiftBaseWith StMSP
-    restoreM     = defaultRestoreM     unStMSP
-#endif
-
 -- | Particularly useful when combined with 'runWebT' to produce
 -- a @m ('Maybe' 'Response')@ from a 'Request'.
 runServerPartT :: ServerPartT m a -> Request -> WebT m a
@@ -342,7 +330,6 @@
     liftIO = FilterT . liftIO
     {-# INLINE liftIO #-}
 
-#if MIN_VERSION_monad_control(1,0,0)
 instance MonadTransControl (FilterT a) where
     type StT (FilterT a) b = StT (Lazy.WriterT (FilterFun a)) b
     liftWith f = FilterT $ liftWith $ \run -> f $ run . unFilterT
@@ -352,18 +339,7 @@
     type StM (FilterT a m) c = ComposeSt (FilterT a) m c
     liftBaseWith = defaultLiftBaseWith
     restoreM     = defaultRestoreM
-#else
-instance MonadTransControl (FilterT a) where
-    newtype StT (FilterT a) b = StFilter {unStFilter :: StT (Lazy.WriterT (FilterFun a)) b}
-    liftWith f = FilterT $ liftWith $ \run -> f $ liftM StFilter . run . unFilterT
-    restoreT = FilterT . restoreT . liftM unStFilter
 
-instance MonadBaseControl b m => MonadBaseControl b (FilterT a m) where
-    newtype StM (FilterT a m) c = StMFilter {unStMFilter :: ComposeSt (FilterT a) m c}
-    liftBaseWith = defaultLiftBaseWith StMFilter
-    restoreM     = defaultRestoreM     unStMFilter
-#endif
-
 -- | A set of functions for manipulating filters.
 --
 -- 'ServerPartT' implements 'FilterMonad' 'Response' so these methods
@@ -397,7 +373,7 @@
     getFilter     = FilterT . listens unFilterFun . unFilterT
 
 -- | The basic 'Response' building object.
-newtype WebT m a = WebT { unWebT :: ErrorT Response (FilterT (Response) (MaybeT m)) a }
+newtype WebT m a = WebT { unWebT :: ExceptT Response (FilterT (Response) (MaybeT m)) a }
     deriving (Functor)
 
 instance MonadCatch m => MonadCatch (WebT m) where
@@ -413,41 +389,23 @@
     liftIO = WebT . liftIO
     {-# INLINE liftIO #-}
 
-#if MIN_VERSION_monad_control(1,0,0)
 instance MonadTransControl WebT where
     type StT WebT a = StT MaybeT
                        (StT (FilterT Response)
-                        (StT (ErrorT Response) a))
+                        (StT (ExceptT Response) a))
     liftWith f = WebT $ liftWith $ \runError ->
                           liftWith $ \runFilter ->
                             liftWith $ \runMaybe ->
                               f $ runMaybe .
                                    runFilter .
-                                    runError . unWebT
+                                    runExceptT . unWebT
     restoreT = WebT . restoreT . restoreT . restoreT
 
 instance MonadBaseControl b m => MonadBaseControl b (WebT m) where
     type StM (WebT m) a = ComposeSt WebT m a
     liftBaseWith = defaultLiftBaseWith
     restoreM     = defaultRestoreM
-#else
-instance MonadTransControl WebT where
-    newtype StT WebT a = StWeb {unStWeb :: StT MaybeT
-                                             (StT (FilterT Response)
-                                               (StT (ErrorT Response) a))}
-    liftWith f = WebT $ liftWith $ \runError ->
-                          liftWith $ \runFilter ->
-                            liftWith $ \runMaybe ->
-                              f $ liftM StWeb . runMaybe .
-                                                  runFilter .
-                                                    runError . unWebT
-    restoreT = WebT . restoreT . restoreT . restoreT . liftM unStWeb
 
-instance MonadBaseControl b m => MonadBaseControl b (WebT m) where
-    newtype StM (WebT m) a = StMWeb {unStMWeb :: ComposeSt WebT m a}
-    liftBaseWith = defaultLiftBaseWith StMWeb
-    restoreM     = defaultRestoreM     unStMWeb
-#endif
 -- | 'UnWebT' is almost exclusively used with 'mapServerPartT'. If you
 -- are not using 'mapServerPartT' then you do not need to wrap your
 -- head around this type. If you are -- the type is not as complex as
@@ -555,13 +513,13 @@
     -- is exactly the semantics expected from objects that take lists
     -- of 'ServerPartT'.
     mzero = WebT $ lift $ lift $ mzero
-    mplus x y =  WebT $ ErrorT $ FilterT $ (lower x) `mplus` (lower y)
-        where lower = (unFilterT . runErrorT . unWebT)
+    mplus x y =  WebT $ ExceptT $ FilterT $ (lower x) `mplus` (lower y)
+        where lower = (unFilterT . runExceptT . unWebT)
 
 instance (Monad m) => FilterMonad Response (WebT m) where
     setFilter f = WebT $ lift $ setFilter $ f
     composeFilter f = WebT . lift . composeFilter $ f
-    getFilter     m = WebT $ ErrorT $ liftM lft $ getFilter (runErrorT $ unWebT m)
+    getFilter     m = WebT $ ExceptT $ liftM lft $ getFilter (runExceptT $ unWebT m)
         where
           lft (Left  r, _) = Left r
           lft (Right a, f) = Right (a, f)
@@ -576,11 +534,11 @@
 -- | For when you really need to unpack a 'WebT' entirely (and not
 -- just unwrap the first layer with 'unWebT').
 ununWebT :: WebT m a -> UnWebT m a
-ununWebT = runMaybeT . Lazy.runWriterT . unFilterT . runErrorT . unWebT
+ununWebT = runMaybeT . Lazy.runWriterT . unFilterT . runExceptT . unWebT
 
 -- | For wrapping a 'WebT' back up.  @'mkWebT' . 'ununWebT' = 'id'@
 mkWebT :: UnWebT m a -> WebT m a
-mkWebT = WebT . ErrorT . FilterT . Lazy.WriterT . MaybeT
+mkWebT = WebT . ExceptT . FilterT . Lazy.WriterT . MaybeT
 
 -- | See 'mapServerPartT' for a discussion of this function.
 mapWebT :: (UnWebT m a -> UnWebT n b)
@@ -798,6 +756,7 @@
 
 -- ErrorT
 
+#if !MIN_VERSION_mtl(2,3,0)
 instance (Error e, ServerMonad m) => ServerMonad (ErrorT e m) where
     askRq     = lift askRq
     localRq f = mapErrorT $ localRq f
@@ -814,6 +773,7 @@
 
 instance (Error e, WebMonad a m) => WebMonad a (ErrorT e m) where
     finishWith    = lift . finishWith
+#endif
 
 -- ExceptT
 
diff --git a/src/Happstack/Server/Internal/Types.hs b/src/Happstack/Server/Internal/Types.hs
--- a/src/Happstack/Server/Internal/Types.hs
+++ b/src/Happstack/Server/Internal/Types.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE TypeSynonymInstances, DeriveDataTypeable, FlexibleInstances, RankNTypes #-}
+{-# LANGUAGE TypeSynonymInstances, DeriveDataTypeable, FlexibleInstances, RankNTypes, CPP #-}
 
 module Happstack.Server.Internal.Types
     (Request(..), Response(..), RqBody(..), Input(..), HeaderPair(..),
@@ -21,7 +21,9 @@
 
 
 import Control.Exception (Exception, SomeException)
+#if !MIN_VERSION_mtl(2,3,0)
 import Control.Monad.Error (Error(strMsg))
+#endif
 import Control.Monad.Fail (MonadFail)
 import Control.Monad.Trans (MonadIO(liftIO))
 import qualified Control.Concurrent.Thread.Group as TG
@@ -246,11 +248,13 @@
 showRsValidator :: Maybe (Response -> IO Response) -> String
 showRsValidator = maybe "Nothing" (const "Just <function>")
 
+#if !MIN_VERSION_mtl(2,3,0)
 -- what should the status code be ?
 instance Error Response where
   strMsg str =
       setHeader "Content-Type" "text/plain; charset=UTF-8" $
        result 500 str
+#endif
 
 -- | an HTTP request
 data Request = Request
diff --git a/src/Happstack/Server/Monads.hs b/src/Happstack/Server/Monads.hs
--- a/src/Happstack/Server/Monads.hs
+++ b/src/Happstack/Server/Monads.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleContexts, CPP #-}
 -- | This module provides four classes and some related functions
 -- which provide 'ServerPartT' with much of its web-centric behavior.
 --
@@ -41,7 +41,9 @@
 
 import Control.Applicative               (Alternative, Applicative)
 import Control.Monad                     (MonadPlus(mzero))
+#if !MIN_VERSION_mtl(2,3,0)
 import Control.Monad.Error               (Error, ErrorT)
+#endif
 import Control.Monad.Trans               (MonadIO(..),MonadTrans(lift))
 import Control.Monad.Trans.Except        (ExceptT)
 import Control.Monad.Reader              (ReaderT)
@@ -71,7 +73,9 @@
 instance (Happstack m, Monoid w) => Happstack (Strict.WriterT   w   m)
 instance (Happstack m, Monoid w) => Happstack (Lazy.RWST      r w s m)
 instance (Happstack m, Monoid w) => Happstack (Strict.RWST    r w s m)
+#if !MIN_VERSION_mtl(2,3,0)
 instance (Happstack m, Error e)  => Happstack (ErrorT e m)
+#endif
 instance (Happstack m, Monoid e) => Happstack (ExceptT e m)
 
 -- | Get a header out of the request.
diff --git a/src/Happstack/Server/Routing.hs b/src/Happstack/Server/Routing.hs
--- a/src/Happstack/Server/Routing.hs
+++ b/src/Happstack/Server/Routing.hs
@@ -109,7 +109,7 @@
 --
 -- > handler :: ServerPart Response
 -- > handler =
--- >     do methodOnly [GET, HEAD]
+-- >     do method [GET, HEAD]
 -- >        ...
 method :: (ServerMonad m, MonadPlus m, MatchMethod method) => method -> m ()
 method meth = guardRq $ \rq -> matchMethod meth (rqMethod rq)
diff --git a/src/Happstack/Server/RqData.hs b/src/Happstack/Server/RqData.hs
--- a/src/Happstack/Server/RqData.hs
+++ b/src/Happstack/Server/RqData.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE DeriveDataTypeable, GeneralizedNewtypeDeriving, FlexibleContexts, FlexibleInstances, MultiParamTypeClasses #-}
+{-# LANGUAGE CPP, DeriveDataTypeable, GeneralizedNewtypeDeriving, FlexibleContexts, FlexibleInstances, MultiParamTypeClasses, StandaloneDeriving, UndecidableInstances #-}
 -- | Functions for extracting values from the query string, form data, cookies, etc.
 --
 -- For in-depth documentation see the following section of the Happstack Crash Course:
@@ -59,7 +59,7 @@
     ) where
 
 import Control.Applicative                      (Applicative((<*>), pure), Alternative((<|>), empty), WrappedMonad(WrapMonad, unwrapMonad))
-import Control.Monad                            (MonadPlus(mzero))
+import Control.Monad                            (MonadPlus(mzero, mplus))
 import Control.Monad.Reader                     (ReaderT(ReaderT, runReaderT), MonadReader(ask, local), mapReaderT)
 import qualified Control.Monad.State.Lazy as Lazy      (StateT, mapStateT)
 import qualified Control.Monad.State.Strict as Strict  (StateT, mapStateT)
@@ -67,7 +67,10 @@
 import qualified Control.Monad.Writer.Strict as Strict (WriterT, mapWriterT)
 import qualified Control.Monad.RWS.Lazy as Lazy        (RWST, mapRWST)
 import qualified Control.Monad.RWS.Strict as Strict    (RWST, mapRWST)
-import Control.Monad.Error                      (Error(noMsg, strMsg), ErrorT, mapErrorT)
+#if !MIN_VERSION_mtl(2,3,0)
+import qualified Control.Monad.Error as DeprecatedError
+#endif
+import Control.Monad.Except                     (throwError)
 import Control.Monad.Trans                      (MonadIO(..), lift)
 import Control.Monad.Trans.Except               (ExceptT, mapExceptT)
 import qualified Data.ByteString.Char8          as P
@@ -90,18 +93,36 @@
 import Network.URI                              (unEscapeString)
 
 newtype ReaderError r e a = ReaderError { unReaderError :: ReaderT r (Either e) a }
-    deriving (Functor, Monad, MonadPlus)
+    deriving (Functor, Monad)
 
-instance (Error e, Monoid e) => MonadReader r (ReaderError r e) where
+#if MIN_VERSION_mtl(2,3,0)
+deriving instance (Monoid e, MonadPlus (Either e)) => MonadPlus (ReaderError r e)
+#else
+deriving instance (Monoid e, DeprecatedError.Error e, MonadPlus (Either e)) => MonadPlus (ReaderError r e)
+#endif
+
+#if MIN_VERSION_mtl(2,3,0)
+instance (Monoid e) => MonadReader r (ReaderError r e) where
+#else
+instance (DeprecatedError.Error e, Monoid e) => MonadReader r (ReaderError r e) where
+#endif
     ask = ReaderError ask
     local f m = ReaderError $ local f (unReaderError m)
 
-instance (Monoid e, Error e) => Applicative (ReaderError r e) where
+#if MIN_VERSION_mtl(2,3,0)
+instance (Monoid e) => Applicative (ReaderError r e) where
+#else
+instance (Monoid e, DeprecatedError.Error e) => Applicative (ReaderError r e) where
+#endif
     pure = return
     (ReaderError (ReaderT f)) <*> (ReaderError (ReaderT a))
         = ReaderError $ ReaderT $ \env -> (f env) `apEither` (a env)
 
-instance (Monoid e, Error e) => Alternative (ReaderError r e) where
+#if MIN_VERSION_mtl(2,3,0)
+instance (MonadPlus (Either e), Monoid e) => Alternative (ReaderError r e) where
+#else
+instance (Monoid e, DeprecatedError.Error e) => Alternative (ReaderError r e) where
+#endif
     empty = unwrapMonad empty
     f <|> g = unwrapMonad $ (WrapMonad f) <|> (WrapMonad g)
 
@@ -123,10 +144,27 @@
     mappend = (SG.<>)
     mconcat errs = Errors $ concatMap unErrors errs
 
-instance Error (Errors String) where
+#if MIN_VERSION_transformers(0,6,0)
+instance (Alternative (Either (Errors a))) => MonadPlus (Either (Errors a)) where
+  mzero = Left (Errors [])
+  (Left _) `mplus` n = n
+  m        `mplus` _ = m
+
+instance Alternative (Either (Errors a)) where
+  empty = Left (Errors [])
+  (Left _) <|> n = n
+  m        <|> _ = m
+#endif
+
+#if !MIN_VERSION_mtl(2,3,0)
+instance DeprecatedError.Error (Errors String) where
     noMsg = Errors []
     strMsg str = Errors [str]
+#endif
 
+strMsg :: a -> Errors a
+strMsg errMsg = Errors [errMsg]
+
 {- commented out to avoid 'Defined but not used' warning.
 readerError :: (Monoid e, Error e) => e -> ReaderError r e b
 readerError e = mapReaderErrorT ((Left e) `apEither`) (return ())
@@ -204,10 +242,12 @@
     localRqEnv f  = Strict.mapRWST (localRqEnv f)
     rqDataError e = lift (rqDataError e)
 
-instance (Monad m, Error e, HasRqData m) => HasRqData (ErrorT e m) where
+#if !MIN_VERSION_mtl(2,3,0)
+instance (Monad m, DeprecatedError.Error e, HasRqData m) => HasRqData (DeprecatedError.ErrorT e m) where
     askRqEnv      = lift askRqEnv
-    localRqEnv f  = mapErrorT (localRqEnv f)
+    localRqEnv f  = DeprecatedError.mapErrorT (localRqEnv f)
     rqDataError e = lift (rqDataError e)
+#endif
 
 instance (Monad m, HasRqData m) => HasRqData (ExceptT e m) where
     askRqEnv      = lift askRqEnv
@@ -263,7 +303,6 @@
     case fromReqURI val of
       (Just a) -> Right a
       _        -> Left $ "readRq failed while parsing key: " ++ key ++ " which has the value: " ++ val
-
 
 -- | convert or validate a value
 --
diff --git a/tests/Happstack/Server/Tests.hs b/tests/Happstack/Server/Tests.hs
--- a/tests/Happstack/Server/Tests.hs
+++ b/tests/Happstack/Server/Tests.hs
@@ -10,9 +10,11 @@
 import Data.ByteString.Lazy.Char8     (pack, unpack)
 import qualified Data.ByteString.Char8 as B
 import qualified Data.ByteString.Lazy  as L
+import Data.List (intercalate)
 import qualified Data.Map              as Map
 import Happstack.Server                      ( Request(..), Method(..), Response(..), ServerPart, Headers, RqBody(Body), HttpVersion(..)
-                                             , ToMessage(..), HeaderPair(..), ok, dir, simpleHTTP'', composeFilter, noContentLength, matchMethod)
+                                             , ToMessage(..), HeaderPair(..), ok, dir, simpleHTTP'', composeFilter, noContentLength, matchMethod
+                                             , look, getDataFn)
 import Happstack.Server.FileServe.BuildingBlocks (sendFileResponse)
 import Happstack.Server.Cookie
 import Happstack.Server.Internal.Compression
@@ -34,6 +36,7 @@
                                 , matchMethodTest
                                 , cookieHeaderOrderTest
                                 , pContentDispositionFilename
+                                , applicativeTest
                                 ]
 
 cookieParserTest :: Test
@@ -247,3 +250,13 @@
     do let doesNotWorkWithOldParserButWithNew = "form-data; filename=\"file.pdf\"; name=\"file\"" :: String
        c <- parseContentDisposition doesNotWorkWithOldParserButWithNew
        assertEqual "parseContentDisposition" c (ContentDisposition "form-data" [("filename","file.pdf"),("name","file")])
+
+applicativeTest :: Test
+applicativeTest =
+  "applicativeTest" ~:
+    do req <- mkRequest GET "/response" [] mempty L.empty
+       res <- flip simpleHTTP'' req $ do
+         Left errors <- getDataFn $ (++) <$> look "a" <*> look "b"
+         pure $ intercalate "," errors
+       let ref = "Parameter not found: a,Parameter not found: b"
+       assertEqual "getDataFn/ReaderError doesn't short-circuit" ref (unpack (rsBody res))