diff --git a/hw-polysemy.cabal b/hw-polysemy.cabal
--- a/hw-polysemy.cabal
+++ b/hw-polysemy.cabal
@@ -1,6 +1,6 @@
 cabal-version:          3.4
 name:                   hw-polysemy
-version:                0.1.0.0
+version:                0.1.1.0
 synopsis:               Opinionated polysemy library
 description:            Opinionated polysemy library.
 license:                Apache-2.0
@@ -20,7 +20,9 @@
 common base                       { build-depends: base                       >= 4.18.2.1   && < 5      }
 
 common bytestring                 { build-depends: bytestring                                  < 0.13   }
+common contravariant              { build-depends: contravariant                               < 1.6    }
 common filepath                   { build-depends: filepath                                    < 1.6    }
+common ghc-prim                   { build-depends: ghc-prim                                    < 0.12   }
 common hedgehog                   { build-depends: hedgehog                                    < 1.5    }
 common polysemy                   { build-depends: polysemy                                    < 2      }
 common polysemy-log               { build-depends: polysemy-log                                < 0.11   }
@@ -49,7 +51,9 @@
 library
   import:               base, project-config,
                         bytestring,
+                        contravariant,
                         filepath,
+                        ghc-prim,
                         hedgehog,
                         polysemy,
                         polysemy-log,
@@ -61,6 +65,7 @@
                         HaskellWorks.Polysemy.ByteString.Strict
                         HaskellWorks.Polysemy.Data.String
                         HaskellWorks.Polysemy.Either
+                        HaskellWorks.Polysemy.Error
                         HaskellWorks.Polysemy.Hedgehog
                         HaskellWorks.Polysemy.Hedgehog.Assert
                         HaskellWorks.Polysemy.Hedgehog.Effect.Hedgehog
diff --git a/src/HaskellWorks/Polysemy/Error.hs b/src/HaskellWorks/Polysemy/Error.hs
new file mode 100644
--- /dev/null
+++ b/src/HaskellWorks/Polysemy/Error.hs
@@ -0,0 +1,20 @@
+module HaskellWorks.Polysemy.Error
+  ( onLeft
+  , onNothing
+  , onLeftM
+  , onNothingM
+  ) where
+
+import           HaskellWorks.Polysemy.Prelude
+
+onLeft :: Monad m => (e -> m a) -> Either e a -> m a
+onLeft f = either f pure
+
+onNothing :: Monad m => m b -> Maybe b -> m b
+onNothing h = maybe h return
+
+onLeftM :: Monad m => (e -> m a) -> m (Either e a) -> m a
+onLeftM f action = onLeft f =<< action
+
+onNothingM :: Monad m => m b -> m (Maybe b) -> m b
+onNothingM h f = onNothing h =<< f
diff --git a/src/HaskellWorks/Polysemy/Prelude.hs b/src/HaskellWorks/Polysemy/Prelude.hs
--- a/src/HaskellWorks/Polysemy/Prelude.hs
+++ b/src/HaskellWorks/Polysemy/Prelude.hs
@@ -1,7 +1,9 @@
 module HaskellWorks.Polysemy.Prelude
   ( Bool(..)
+  , Char(..)
   , Maybe(..)
   , Either(..)
+
   , String
   , Text
   , ByteString
@@ -10,35 +12,105 @@
   , Int16
   , Int32
   , Int64
+  , Integer
   , Word
   , Word8
   , Word16
   , Word32
   , Word64
+  , Float
+  , Double
   , FilePath
+  , Void
 
   , Eq(..)
   , Ord(..)
+  , Num(..)
   , Show(..)
+  , IsString(..)
   , tshow
 
+  , bool
   , const
+
+  , absurd
+  , vacuous
+
   , either
+  , lefts
+  , rights
+  , isLeft
+  , isRight
+  , fromLeft
+  , fromRight
+
   , maybe
+  , isJust
+  , isNothing
+  , fromMaybe
+  , listToMaybe
+  , maybeToList
+  , catMaybes
+  , mapMaybe
+
   , fst
+  , flip
   , snd
   , id
+  , seq
+  , curry
+  , uncurry
+  , ($!)
   , ($)
   , (&)
   , (.)
   , (</>)
 
   , void
+  , mapM_
+  , forM
+  , forM_
+  , sequence_
+  , (=<<)
+  , (>=>)
+  , (<=<)
+  , forever
+  , join
+  , msum
+  , mfilter
+  , filterM
+  , foldM
+  , foldM_
+  , replicateM
+  , replicateM_
+  , guard
+  , when
+  , unless
+  , liftM
+  , liftM2
+  , liftM3
+  , liftM4
+  , liftM5
+  , ap
+  , (<$!>)
 
+  , (<$>)
+
+  , (<**>)
+  , liftA
+  , liftA3
+  , optional
+  , asum
+
   , for_
 
   , Monad(..)
+  , MonadFail(..)
+  , MonadPlus(..)
   , Applicative(..)
+  , Alternative(..)
+  , Contravariant(..)
+  , Divisible(..)
   , Functor(..)
   , Bifunctor(..)
   , Semigroup(..)
@@ -52,6 +124,8 @@
   , HasCallStack
   , withFrozenCallStack
 
+  , Generic
+
   , IOException
   , SomeException(..)
   ) where
@@ -62,10 +136,13 @@
 import           Data.Bifunctor
 import           Data.Bool
 import           Data.ByteString
+import           Data.Char
 import           Data.Either
 import           Data.Eq
 import           Data.Foldable
 import           Data.Function
+import           Data.Functor.Contravariant
+import           Data.Functor.Contravariant.Divisible
 import           Data.Int
 import           Data.Maybe
 import           Data.Monoid
@@ -75,13 +152,16 @@
 import           Data.Text
 import           Data.Traversable
 import           Data.Tuple
+import           Data.Void
 import           Data.Word
+import           GHC.Base
+import           GHC.Generics
+import           GHC.Num
 import           GHC.Stack
 import           System.FilePath
-import           System.IO
 import           Text.Show
 
-import qualified Data.Text           as T
+import qualified Data.Text                            as T
 
 tshow :: Show a => a -> Text
 tshow = T.pack . show