diff --git a/Changes.md b/Changes.md
--- a/Changes.md
+++ b/Changes.md
@@ -1,5 +1,13 @@
 # Change log for the `probability` package
 
+## 0.2.8
+
+ * `Numeric.Probability.Either` -> `Control.Monad.Trans.Except`
+   Few functions exposed `EitherT` in their signatures,
+   but `Numeric.Probability.Either` was private.
+   Thus its removal should not be noticed by library users.
+
+
 ## 0.2.7
 
  * support `random-1.2`
diff --git a/ToDo b/ToDo
--- a/ToDo
+++ b/ToDo
@@ -1,6 +1,3 @@
-Numeric.Probability.Either -> Control.Monad.Trans.Except
-
-
 Object -> Experiment?
 
 Object
diff --git a/probability.cabal b/probability.cabal
--- a/probability.cabal
+++ b/probability.cabal
@@ -1,6 +1,6 @@
 Cabal-Version:      1.24
 Name:               probability
-Version:            0.2.7
+Version:            0.2.8
 License:            BSD3
 License-File:       COPYRIGHT
 Author:             Martin Erwig <erwig@eecs.oregonstate.edu>, Steve Kollmansberger
@@ -29,7 +29,7 @@
 Source-Repository this
   type:     darcs
   location: http://code.haskell.org/~thielema/probability/
-  tag:      0.2.7
+  tag:      0.2.8
 
 
 Flag splitBase
@@ -37,17 +37,13 @@
 
 Library
   Build-Depends:
-    utility-ht >=0.0.6 && <0.1,
-    transformers >=0.0.1 && <0.6
+    utility-ht >=0.0.12 && <0.1,
+    transformers >=0.4 && <0.7
   If flag(splitBase)
     Build-Depends:
       containers >=0.1 && <0.7,
       random >=1.0 && <1.3,
       base >=2 && <5
-    If impl(ghc>=8.8)
-      Hs-Source-Dirs: src-fail/from-4.13/
-    Else
-      Hs-Source-Dirs: src-fail/before-4.13/
   Else
     Build-Depends:
       special-functors >=1.0 && <1.1,
@@ -86,4 +82,3 @@
     Numeric.Probability.Monad
     Numeric.Probability.PrintList
     Numeric.Probability.Show
-    Numeric.Probability.Either
diff --git a/src-fail/before-4.13/Numeric/Probability/Either.hs b/src-fail/before-4.13/Numeric/Probability/Either.hs
deleted file mode 100644
--- a/src-fail/before-4.13/Numeric/Probability/Either.hs
+++ /dev/null
@@ -1,37 +0,0 @@
-module Numeric.Probability.Either where
-
-import Control.Monad.Instances ()
-
-import Control.Applicative (Applicative, pure, (<*>), liftA2, )
-
-
-newtype EitherT a m b = EitherT (m (Either a b))
-
-instance Functor m => Functor (EitherT a m) where
-   fmap f (EitherT m) = EitherT $ fmap (fmap f) m
-
-instance Applicative m => Applicative (EitherT a m) where
-   pure a = EitherT $ pure $ Right a
-   EitherT af <*> EitherT am =
-      EitherT $
-      liftA2 (\ef em ->
-         case ef of
-            Left b -> Left b
-            Right f ->
-               case em of
-                  Left b -> Left b
-                  Right m -> Right $ f m) af am
-
-instance Monad m => Monad (EitherT a m) where
-   return a = EitherT $ return $ Right a
-   EitherT m >>= f  =  EitherT $ do
-      e <- m
-      case e of
-         Left b -> return $ Left b
-         Right a ->
-            case f a of
-               EitherT n -> n
-   fail s = EitherT $ fail s
-
-throw :: Applicative m => a -> EitherT a m b
-throw a = EitherT $ pure $ Left a
diff --git a/src-fail/from-4.13/Numeric/Probability/Either.hs b/src-fail/from-4.13/Numeric/Probability/Either.hs
deleted file mode 100644
--- a/src-fail/from-4.13/Numeric/Probability/Either.hs
+++ /dev/null
@@ -1,39 +0,0 @@
-module Numeric.Probability.Either where
-
-import Control.Monad.Instances ()
-
-import Control.Applicative (Applicative, pure, (<*>), liftA2, )
-
-
-newtype EitherT a m b = EitherT (m (Either a b))
-
-instance Functor m => Functor (EitherT a m) where
-   fmap f (EitherT m) = EitherT $ fmap (fmap f) m
-
-instance Applicative m => Applicative (EitherT a m) where
-   pure a = EitherT $ pure $ Right a
-   EitherT af <*> EitherT am =
-      EitherT $
-      liftA2 (\ef em ->
-         case ef of
-            Left b -> Left b
-            Right f ->
-               case em of
-                  Left b -> Left b
-                  Right m -> Right $ f m) af am
-
-instance Monad m => Monad (EitherT a m) where
-   return a = EitherT $ return $ Right a
-   EitherT m >>= f  =  EitherT $ do
-      e <- m
-      case e of
-         Left b -> return $ Left b
-         Right a ->
-            case f a of
-               EitherT n -> n
-
-instance MonadFail m => MonadFail (EitherT a m) where
-   fail s = EitherT $ fail s
-
-throw :: Applicative m => a -> EitherT a m b
-throw a = EitherT $ pure $ Left a
diff --git a/src/Numeric/Probability/Distribution.hs b/src/Numeric/Probability/Distribution.hs
--- a/src/Numeric/Probability/Distribution.hs
+++ b/src/Numeric/Probability/Distribution.hs
@@ -5,6 +5,7 @@
 import Numeric.Probability.Show (showR)
 import qualified Numeric.Probability.Shape as Shape
 
+import qualified Control.Functor.HT as FuncHT
 import Control.Applicative (Applicative(..))
 import Control.Monad (liftM, liftM2, join, )
 
@@ -121,9 +122,7 @@
 
 
 -- ** Auxiliary functions for constructing and working with distributions
-lift :: (Num prob) =>
-   ([(a,prob)] -> [(a,prob)]) ->
-   T prob a -> T prob a
+lift :: (Num prob) => ([(a,prob)] -> [(b,prob)]) -> T prob a -> T prob b
 lift f  = Cons . f . decons
 
 size :: T prob a -> Int
@@ -358,10 +357,9 @@
 
 select :: (Num prob, Ord prob, Ord a) =>
    (prob -> Bool) -> T prob a -> T prob (Select a)
-select condp (Cons d) =
+select condp = lift $ \d ->
    let (d1,d2) = Map.partition condp $ Map.fromListWith (+) d
-   in  Cons $
-          (Other, Fold.sum d2) :
+   in  (Other, Fold.sum d2) :
           List.map (mapFst Case) (Map.toAscList d1)
 
 fromFreqs :: (Fractional prob) => [(a,prob)] -> T prob a
@@ -375,7 +373,7 @@
 mapMaybe :: (Fractional prob) =>
    (a -> Maybe b) -> T prob a -> T prob b
 mapMaybe f =
-   fromFreqs . Maybe.mapMaybe (\(x,p) -> fmap (flip (,) p) $ f x) . decons
+   fromFreqs . Maybe.mapMaybe (FuncHT.mapFst f) . decons
 
 
 -- | selecting from distributions
diff --git a/src/Numeric/Probability/Object.hs b/src/Numeric/Probability/Object.hs
--- a/src/Numeric/Probability/Object.hs
+++ b/src/Numeric/Probability/Object.hs
@@ -20,10 +20,10 @@
 import qualified Numeric.Probability.Distribution as Dist
 import qualified Numeric.Probability.Random as Rnd
 import qualified Numeric.Probability.Shape as Shape
-import qualified Numeric.Probability.Either as PE
 
 import qualified Data.List as List
 
+import qualified Control.Monad.Trans.Except as ME
 import Control.Monad (liftM, )
 
 
@@ -37,9 +37,9 @@
 instance Fractional prob => C prob (Dist.T prob) where
    fromFrequencies = Dist.fromFreqs
 
-instance C prob obj => C prob (PE.EitherT b obj) where
+instance C prob obj => C prob (ME.ExceptT b obj) where
    fromFrequencies =
-      PE.EitherT . liftM Right . fromFrequencies
+      ME.ExceptT . liftM Right . fromFrequencies
 
 
 
diff --git a/src/Numeric/Probability/Transition.hs b/src/Numeric/Probability/Transition.hs
--- a/src/Numeric/Probability/Transition.hs
+++ b/src/Numeric/Probability/Transition.hs
@@ -3,7 +3,7 @@
 
 import qualified Numeric.Probability.Distribution as Dist
 
-import qualified Numeric.Probability.Either as PE
+import qualified Control.Monad.Trans.Except as ME
 
 import qualified Data.Map as Map
 
@@ -75,13 +75,13 @@
 any action after a 'go' is ignored.
 -}
 fix :: (Num prob, Ord a, Ord b) =>
-   ((a -> PE.EitherT a (Dist.T prob) b) ->
-    (a -> PE.EitherT a (Dist.T prob) b)) ->
+   ((a -> ME.ExceptT a (Dist.T prob) b) ->
+    (a -> ME.ExceptT a (Dist.T prob) b)) ->
    Dist.T prob a -> Dist.T prob b
 fix f =
    untilLeft $ \a ->
-      case f PE.throw a of
-         PE.EitherT m -> fmap (either Right Left) m
+      case f ME.throwE a of
+         ME.ExceptT m -> fmap (either Right Left) m
 
 
 -- * Spreading changes into transitions