diff --git a/Data/Bimap.hs b/Data/Bimap.hs
--- a/Data/Bimap.hs
+++ b/Data/Bimap.hs
@@ -36,6 +36,8 @@
     lookupR,
     (!),
     (!>),
+    (!?),
+    (!?>),
     -- * Construction
     empty,
     singleton,
@@ -103,7 +105,7 @@
 import           Data.Typeable
 
 #if __GLASGOW_HASKELL__ >= 708
-import qualified GHC.Exts            as GHCExts
+import qualified Data.BimapExt       as GHCExts
 #endif
 import           GHC.Generics        (Generic)
 
@@ -346,6 +348,9 @@
 This function will @return@ the result in the monad, or @fail@ if
 the value isn't in the bimap.
 
+Note that the signature differs slightly from Data.Map's @lookup@. This one is more general -
+it functions the same way as the "original" if @m@ is cast (or inferred) to Maybe.
+
 /Version: 0.2/-}
 lookup :: (Ord a, Ord b, MonadThrow m)
        => a -> Bimap a b -> m b
@@ -357,6 +362,8 @@
 {-| /O(log n)/.
 A version of 'lookup' that is specialized to the right key,
 and returns the corresponding left key.
+
+
 /Version: 0.2/-}
 lookupR :: (Ord a, Ord b, MonadThrow m)
         => b -> Bimap a b -> m a
@@ -378,6 +385,16 @@
 /Version: 0.2/-}
 (!>) :: (Ord a, Ord b) => Bimap a b -> b -> a
 (!>) bi y = fromMaybe (error "Data.Bimap.(!>): Right key not found") $ lookupR y bi
+
+{-| /O(log n)/.
+See 'lookup'. -}
+(!?) :: (Ord a, Ord b, MonadThrow m) => Bimap a b -> a -> m b
+(!?) = flip lookup
+
+{-| /O(log n)/.
+See 'lookupR'. -}
+(!?>) :: (Ord a, Ord b, MonadThrow m) => Bimap a b -> b -> m a
+(!?>) = flip lookupR
 
 {-| /O(n*log n)/.
 Build a map from a list of pairs. If there are any overlapping
diff --git a/Data/BimapExt.hs b/Data/BimapExt.hs
new file mode 100644
--- /dev/null
+++ b/Data/BimapExt.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE Trustworthy #-}
+{-|
+An auxiliary module that exports the 'IsList' class from "GHC.Exts". We use
+this intermediate module to isolate a safe feature from an otherwise non-safe
+module, and prevent all of "Data.Bimap" from being marked as not safe just
+because we are importing "GHC.Exts".
+
+The module only exports a class, and the class does not define any methods in
+an unsafe way. We therefore consider it safe and mark this module as
+trustworthy.
+-}
+module Data.BimapExt (
+    IsList(..)
+) where
+
+import GHC.Exts (IsList(..))
diff --git a/bimap.cabal b/bimap.cabal
--- a/bimap.cabal
+++ b/bimap.cabal
@@ -1,6 +1,6 @@
-cabal-version:       >= 1.8
+cabal-version:       >= 1.10
 name:                bimap
-version:             0.4.0
+version:             0.5.0
 synopsis:            Bidirectional mapping between two key types
 description:
   A data structure representing a bidirectional mapping between two
@@ -22,11 +22,21 @@
   build-depends:       base >= 4 && <5, containers, deepseq, exceptions
   if impl(ghc < 7.6.1)
     build-depends: ghc-prim
-  extensions:          DeriveDataTypeable
+    default-extensions:  CPP
+                         DeriveGeneric
+                         TypeFamilies
+  else
+    default-extensions: CPP
+                        TypeFamilies
+  default-language:    Haskell98   
   ghc-options:         -Wall
   exposed-modules:
       Data.Bimap
 
+  if impl(ghc >= 7.8)
+    other-modules:
+      Data.BimapExt
+
 test-suite tests
     type:            exitcode-stdio-1.0
     main-is:         Test/RunTests.hs
@@ -40,7 +50,8 @@
                      template-haskell >= 2 && < 3
     if impl(ghc < 7.6.1)
       build-depends: ghc-prim
-  extensions:        DeriveDataTypeable
+  default-extensions:  TemplateHaskell
+  default-language:    Haskell98   
 
 source-repository head
     type:         git