diff --git a/library/Rebase/Data/Bifunctor.hs b/library/Rebase/Data/Bifunctor.hs
--- a/library/Rebase/Data/Bifunctor.hs
+++ b/library/Rebase/Data/Bifunctor.hs
@@ -1,7 +1,24 @@
 module Rebase.Data.Bifunctor
 (
   module Data.Bifunctor,
+  mapLeft,
+  mapRight,
 )
 where
 
 import Data.Bifunctor
+
+
+-- |
+-- A more meaningful and conflict-free alias for 'first'.
+{-# INLINE mapLeft #-}
+mapLeft :: Bifunctor p => (a -> b) -> p a c -> p b c
+mapLeft =
+  first
+
+-- |
+-- A more meaningful and conflict-free alias for 'second'.
+{-# INLINE mapRight #-}
+mapRight :: Bifunctor p => (b -> c) -> p a b -> p a c
+mapRight =
+  second
diff --git a/library/Rebase/Prelude.hs b/library/Rebase/Prelude.hs
--- a/library/Rebase/Prelude.hs
+++ b/library/Rebase/Prelude.hs
@@ -65,7 +65,7 @@
 -- either
 -------------------------
 import Rebase.Control.Monad.Trans.Either as Exports hiding (left, right)
-import Rebase.Data.Either.Combinators as Exports hiding (isLeft, isRight)
+import Rebase.Data.Either.Combinators as Exports hiding (isLeft, isRight, mapLeft, mapRight)
 import Rebase.Data.Either.Validation as Exports
 
 -- fail
diff --git a/rebase.cabal b/rebase.cabal
--- a/rebase.cabal
+++ b/rebase.cabal
@@ -1,7 +1,7 @@
 name:
   rebase
 version:
-  0.5
+  0.5.1
 synopsis:
   A more progressive alternative to the "base" package
 description: