diff --git a/ditto.cabal b/ditto.cabal
--- a/ditto.cabal
+++ b/ditto.cabal
@@ -1,5 +1,5 @@
 Name:          ditto
-Version:       0.3
+Version:       0.3.1
 Synopsis:      ditto is a type-safe HTML form generation and validation library
 Description:   ditto follows in the footsteps of formlets and
                digestive-functors <= 0.2. It provides a
diff --git a/src/Ditto/Backend.hs b/src/Ditto/Backend.hs
--- a/src/Ditto/Backend.hs
+++ b/src/Ditto/Backend.hs
@@ -56,7 +56,7 @@
   MissingDefaultValue -> "Missing default value."
 
 -- | A Class to lift a 'CommonFormError' into an application-specific error type
-class FormError err input | err -> input where
+class FormError input err where
   commonFormError :: CommonFormError input -> err
 
 instance FormError Text Text where
@@ -73,7 +73,7 @@
   -- | Parse the input into a string. This is used for simple text fields
   -- among other things
   --
-  getInputString :: (FormError error input) => input -> Either error String
+  getInputString :: (FormError input err) => input -> Either err String
   getInputString input =
     case getInputStrings input of
       [] -> Left (commonFormError $ NoStringFound input)
@@ -86,7 +86,7 @@
 
   -- | Parse the input value into 'Text'
   --
-  getInputText :: (FormError error input) => input -> Either error Text
+  getInputText :: (FormError input err) => input -> Either err Text
   getInputText input =
     case getInputTexts input of
       [] -> Left (commonFormError $ NoStringFound input)
@@ -100,4 +100,4 @@
 
   -- | Get a file descriptor for an uploaded file
   --
-  getInputFile :: (FormError error input) => input -> Either error (FileType input)
+  getInputFile :: (FormError input err) => input -> Either err (FileType input)
diff --git a/src/Ditto/Generalized.hs b/src/Ditto/Generalized.hs
--- a/src/Ditto/Generalized.hs
+++ b/src/Ditto/Generalized.hs
@@ -11,12 +11,12 @@
 import qualified Ditto.Generalized.Internal as G
 
 -- | used for constructing elements like @\<input type=\"text\"\>@, which pure a single input value.
-input :: (Monad m, FormError err input) => (input -> Either err a) -> (FormId -> a -> view) -> a -> Form m input err view a
+input :: (Monad m, FormError input err) => (input -> Either err a) -> (FormId -> a -> view) -> a -> Form m input err view a
 input = G.input getFormId
 
 -- | used for elements like @\<input type=\"submit\"\>@ which are not always present in the form submission data.
 inputMaybe
-  :: (Monad m, FormError err input)
+  :: (Monad m, FormError input err)
   => (input -> Either err a)
   -> (FormId -> Maybe a -> view)
   -> Maybe a
@@ -25,7 +25,7 @@
 
 -- | used to construct elements with optional initial values, which are still required
 inputMaybeReq
-  :: (Monad m, FormError err input)
+  :: (Monad m, FormError input err)
   => (input -> Either err a)
   -> (FormId -> Maybe a -> view)
   -> Maybe a
@@ -41,14 +41,14 @@
 
 -- | used for @\<input type=\"file\"\>@
 inputFile
-  :: forall m input err view. (Monad m, FormInput input, FormError err input)
+  :: forall m input err view. (Monad m, FormInput input, FormError input err)
   => (FormId -> view)
   -> Form m input err view (FileType input)
 inputFile = G.inputFile getFormId
 
 -- | used for groups of checkboxes, @\<select multiple=\"multiple\"\>@ boxes
 inputMulti
-  :: forall m input err view a lbl. (FormError err input, FormInput input, Monad m)
+  :: forall m input err view a lbl. (FormError input err, FormInput input, Monad m)
   => [(a, lbl)] -- ^ value, label, initially checked
   -> (FormId -> [(FormId, Int, lbl, Bool)] -> view) -- ^ function which generates the view
   -> (a -> Bool) -- ^ isChecked/isSelected initially
@@ -57,7 +57,7 @@
 
 -- | radio buttons, single @\<select\>@ boxes
 inputChoice
-  :: forall a m err input lbl view. (FormError err input, FormInput input, Monad m)
+  :: forall a m err input lbl view. (FormError input err, FormInput input, Monad m)
   => (a -> Bool) -- ^ is default
   -> [(a, lbl)] -- ^ value, label
   -> (FormId -> [(FormId, Int, lbl, Bool)] -> view) -- ^ function which generates the view
@@ -66,7 +66,7 @@
 
 -- | radio buttons, single @\<select\>@ boxes
 inputChoiceForms
-  :: forall a m err input lbl view. (Monad m, FormError err input, FormInput input)
+  :: forall a m err input lbl view. (Monad m, FormError input err, FormInput input)
   => a
   -> [(Form m input err view a, lbl)] -- ^ value, label
   -> (FormId -> [(FormId, Int, FormId, view, lbl, Bool)] -> view) -- ^ function which generates the view
diff --git a/src/Ditto/Generalized/Internal.hs b/src/Ditto/Generalized/Internal.hs
--- a/src/Ditto/Generalized/Internal.hs
+++ b/src/Ditto/Generalized/Internal.hs
@@ -18,7 +18,7 @@
 
 -- | used for constructing elements like @\<input type=\"text\"\>@, which pure a single input value.
 input
-  :: (Monad m, FormError err input)
+  :: forall m input err a view. (Monad m, FormError input err)
   => FormState m input FormId
   -> (input -> Either err a)
   -> (FormId -> a -> view)
@@ -57,11 +57,11 @@
           )
       Missing -> pure
         ( View $ const $ toView i initialValue
-        , pure $ Error [(unitRange i, commonFormError (InputMissing i))]
+        , pure $ Error [(unitRange i, commonFormError (InputMissing i :: CommonFormError input) :: err)]
         )
 
 inputMaybeReq
-  :: (Monad m, FormError err input)
+  :: forall m input err a view. (Monad m, FormError input err)
   => FormState m input FormId
   -> (input -> Either err a)
   -> (FormId -> Maybe a -> view)
@@ -82,7 +82,7 @@
                        , unProved = x
                        }
                    )
-              Nothing -> pure $ Error [(unitRange i, commonFormError MissingDefaultValue)]
+              Nothing -> pure $ Error [(unitRange i, commonFormError (MissingDefaultValue :: CommonFormError input) :: err)]
           )
       Found x -> case fromInput x of
         Right a -> pure
@@ -101,13 +101,13 @@
           )
       Missing -> pure
         ( View $ const $ toView i initialValue
-        , pure $ Error [(unitRange i, commonFormError (InputMissing i))]
+        , pure $ Error [(unitRange i, commonFormError (InputMissing i :: CommonFormError input) :: err)]
         )
 
 
 -- | used for elements like @\<input type=\"submit\"\>@ which are not always present in the form submission data.
 inputMaybe
-  :: (Monad m, FormError err input)
+  :: (Monad m, FormError input err)
   => FormState m input FormId
   -> (input -> Either err a)
   -> (FormId -> Maybe a -> view)
@@ -176,7 +176,7 @@
 
 -- | used for @\<input type=\"file\"\>@
 inputFile
-  :: forall m input err view. (Monad m, FormInput input, FormError err input)
+  :: forall m input err view. (Monad m, FormInput input, FormError input err)
   => FormState m input FormId
   -> (FormId -> view)
   -> Form m input err view (FileType input)
@@ -188,7 +188,7 @@
       Default ->
         pure
           ( View $ const $ toView i
-          , pure $ Error [(unitRange i, commonFormError (InputMissing i))]
+          , pure $ Error [(unitRange i, commonFormError (InputMissing i :: CommonFormError input) :: err)]
           )
       Found x -> case getInputFile' x of
         Right a -> pure
@@ -208,16 +208,16 @@
       Missing ->
         pure
           ( View $ const $ toView i
-          , pure $ Error [(unitRange i, commonFormError (InputMissing i))]
+          , pure $ Error [(unitRange i, commonFormError (InputMissing i :: CommonFormError input) ::err)]
           )
   where
     -- just here for the type-signature to make the type-checker happy
-    getInputFile' :: (FormError err input) => input -> Either err (FileType input)
+    getInputFile' :: (FormError input err) => input -> Either err (FileType input)
     getInputFile' = getInputFile
 
 -- | used for groups of checkboxes, @\<select multiple=\"multiple\"\>@ boxes
 inputMulti
-  :: forall m input err view a lbl. (FormError err input, FormInput input, Monad m)
+  :: forall m input err view a lbl. (FormError input err, FormInput input, Monad m)
   => FormState m input FormId
   -> [(a, lbl)] -- ^ value, label, initially checked
   -> (FormId -> [(FormId, Int, lbl, Bool)] -> view) -- ^ function which generates the view
@@ -274,7 +274,7 @@
 
 -- | radio buttons, single @\<select\>@ boxes
 inputChoice
-  :: forall a m err input lbl view. (FormError err input, FormInput input, Monad m)
+  :: forall a m err input lbl view. (FormError input err, FormInput input, Monad m)
   => FormState m input FormId
   -> (a -> Bool) -- ^ is default
   -> [(a, lbl)] -- ^ value, label
@@ -318,7 +318,7 @@
             Nothing ->
               pure
                 ( View $ const view'
-                , pure $ Error [(unitRange i, commonFormError (InputMissing i))]
+                , pure $ Error [(unitRange i, commonFormError (InputMissing i :: CommonFormError input) :: err)]
                 )
             (Just val) -> mkOk i view' val
   where
@@ -326,7 +326,7 @@
     mkOk' i view' Nothing =
       pure
         ( View $ const $ view'
-        , pure $ Error [(unitRange i, commonFormError MissingDefaultValue)]
+        , pure $ Error [(unitRange i, commonFormError (MissingDefaultValue :: CommonFormError input) :: err)]
         )
     markSelected :: [(a, lbl)] -> ([(a, lbl, Bool)], Maybe a)
     markSelected cs =
@@ -349,7 +349,7 @@
 
 -- | radio buttons, single @\<select\>@ boxes
 inputChoiceForms
-  :: forall a m err input lbl view. (Monad m, FormError err input, FormInput input)
+  :: forall a m err input lbl view. (Monad m, FormError input err, FormInput input)
   => FormState m input FormId
   -> a
   -> [(Form m input err view a, lbl)] -- ^ value, label
@@ -397,7 +397,7 @@
                     (v0, _) <- unForm frm
                     pure ((fid, val, iview, unView v0 [], lbl, selected) : views, res)
               )
-              ([], pure $ Error [(unitRange i, commonFormError (InputMissing i))])
+              ([], pure $ Error [(unitRange i, commonFormError (InputMissing i :: CommonFormError input) :: err)])
               (choices')
           let view' = mkView i (reverse choices'')
           pure (View (const view'), mres)
diff --git a/src/Ditto/Generalized/Named.hs b/src/Ditto/Generalized/Named.hs
--- a/src/Ditto/Generalized/Named.hs
+++ b/src/Ditto/Generalized/Named.hs
@@ -12,13 +12,13 @@
 import qualified Ditto.Generalized.Internal as G
 
 -- | used for constructing elements like @\<input type=\"text\"\>@, which pure a single input value.
-input :: (Monad m, FormError err input) => String -> (input -> Either err a) -> (FormId -> a -> view) -> a -> Form m input err view a
+input :: (Monad m, FormError input err) => String -> (input -> Either err a) -> (FormId -> a -> view) -> a -> Form m input err view a
 input name = G.input (getNamedFormId name)
 
 
 -- | used to construct elements with optional initial values, which are still required
 inputMaybeReq
-  :: (Monad m, FormError err input)
+  :: (Monad m, FormError input err)
   => String
   -> (input -> Either err a)
   -> (FormId -> Maybe a -> view)
@@ -28,7 +28,7 @@
 
 -- | used for elements like @\<input type=\"submit\"\>@ which are not always present in the form submission data.
 inputMaybe
-  :: (Monad m, FormError err input)
+  :: (Monad m, FormError input err)
   => String
   -> (input -> Either err a)
   -> (FormId -> Maybe a -> view)
@@ -46,7 +46,7 @@
 
 -- | used for @\<input type=\"file\"\>@
 inputFile
-  :: forall m input err view. (Monad m, FormInput input, FormError err input)
+  :: forall m input err view. (Monad m, FormInput input, FormError input err)
   => String
   -> (FormId -> view)
   -> Form m input err view (FileType input)
@@ -54,7 +54,7 @@
 
 -- | used for groups of checkboxes, @\<select multiple=\"multiple\"\>@ boxes
 inputMulti
-  :: forall m input err view a lbl. (FormError err input, FormInput input, Monad m)
+  :: forall m input err view a lbl. (FormError input err, FormInput input, Monad m)
   => String
   -> [(a, lbl)] -- ^ value, label, initially checked
   -> (FormId -> [(FormId, Int, lbl, Bool)] -> view) -- ^ function which generates the view
@@ -64,7 +64,7 @@
 
 -- | radio buttons, single @\<select\>@ boxes
 inputChoice
-  :: forall a m err input lbl view. (FormError err input, FormInput input, Monad m)
+  :: forall a m err input lbl view. (FormError input err, FormInput input, Monad m)
   => String
   -> (a -> Bool) -- ^ is default
   -> [(a, lbl)] -- ^ value, label
@@ -74,7 +74,7 @@
 
 -- | radio buttons, single @\<select\>@ boxes
 inputChoiceForms
-  :: forall a m err input lbl view. (Monad m, FormError err input, FormInput input)
+  :: forall a m err input lbl view. (Monad m, FormError input err, FormInput input)
   => String
   -> a
   -> [(Form m input err view a, lbl)] -- ^ value, label