diff --git a/hw-int.cabal b/hw-int.cabal
--- a/hw-int.cabal
+++ b/hw-int.cabal
@@ -1,7 +1,7 @@
 cabal-version: 2.2
 
 name:                   hw-int
-version:                0.0.1.0
+version:                0.0.2.0
 synopsis:               Additional facilities for Integers
 description:            Additional faciltiies for Integers. Please see README.md
 category:               Data
@@ -45,6 +45,8 @@
                         HaskellWorks.Data.Int.Narrow.Narrow32
                         HaskellWorks.Data.Int.Narrow.Narrow64
                         HaskellWorks.Data.Int.Narrow.Narrow8
+                        HaskellWorks.Data.Int.Signed
+                        HaskellWorks.Data.Int.Unsigned
                         HaskellWorks.Data.Int.Widen
                         HaskellWorks.Data.Int.Widen.Widen16
                         HaskellWorks.Data.Int.Widen.Widen32
@@ -74,7 +76,7 @@
                       , hw-int
   default-language:     Haskell2010
   type:                 exitcode-stdio-1.0
-  ghc-options:          -threaded
+  ghc-options:          -threaded -rtsopts -with-rtsopts=-N
   main-is:              DoctestDriver.hs
   HS-Source-Dirs:       doctest
   build-tool-depends:   doctest-discover:doctest-discover
diff --git a/src/HaskellWorks/Data/Int/Narrow.hs b/src/HaskellWorks/Data/Int/Narrow.hs
--- a/src/HaskellWorks/Data/Int/Narrow.hs
+++ b/src/HaskellWorks/Data/Int/Narrow.hs
@@ -1,8 +1,102 @@
+{-# LANGUAGE MultiParamTypeClasses #-}
+
 module HaskellWorks.Data.Int.Narrow
   ( module X
+  , Narrow(..)
   ) where
 
-import HaskellWorks.Data.Int.Narrow.Narrow8   as X
-import HaskellWorks.Data.Int.Narrow.Narrow16  as X
-import HaskellWorks.Data.Int.Narrow.Narrow32  as X
-import HaskellWorks.Data.Int.Narrow.Narrow64  as X
+import Data.Int
+import Data.Word
+
+import HaskellWorks.Data.Int.Narrow.Narrow16 as X
+import HaskellWorks.Data.Int.Narrow.Narrow32 as X
+import HaskellWorks.Data.Int.Narrow.Narrow64 as X
+import HaskellWorks.Data.Int.Narrow.Narrow8  as X
+
+class Narrow a b where
+  -- | Cast the value to a smaller size.
+  --
+  -- If the value does not fit in the smaller size, data will be lost.
+  --
+  -- This gives a better indication of intent than `Prelude.fromIntegral'.
+  narrow :: a -> b
+
+instance Narrow Int8 Int8 where
+  narrow = id
+  {-# INLINE narrow #-}
+
+instance Narrow Int16 Int8 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Int32 Int8 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Int64 Int8 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Int16 Int16 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Int32 Int16 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Int64 Int16 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Int32 Int32 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Int64 Int32 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Int64 Int64 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word8 Word8 where
+  narrow = id
+  {-# INLINE narrow #-}
+
+instance Narrow Word16 Word8 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word32 Word8 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word64 Word8 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word16 Word16 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word32 Word16 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word64 Word16 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word32 Word32 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word64 Word32 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
+
+instance Narrow Word64 Word64 where
+  narrow = fromIntegral
+  {-# INLINE narrow #-}
diff --git a/src/HaskellWorks/Data/Int/Signed.hs b/src/HaskellWorks/Data/Int/Signed.hs
new file mode 100644
--- /dev/null
+++ b/src/HaskellWorks/Data/Int/Signed.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE TypeFamilies #-}
+
+module HaskellWorks.Data.Int.Signed
+  ( Signed(..)
+  ) where
+
+import Data.Int
+import Data.Word
+
+class Signed a where
+  type SignedOf a
+
+  -- | Cast the value to a larger size.
+  --
+  -- This is safer to use than 'Prelude.fromIntegral'.
+  signed :: a -> SignedOf a
+
+instance Signed Word8 where
+  type SignedOf Word8 = Int8
+
+  signed = fromIntegral
+  {-# INLINE signed #-}
+
+instance Signed Word16 where
+  type SignedOf Word16 = Int16
+
+  signed = fromIntegral
+  {-# INLINE signed #-}
+
+instance Signed Word32 where
+  type SignedOf Word32 = Int32
+
+  signed = fromIntegral
+  {-# INLINE signed #-}
+
+instance Signed Word64 where
+  type SignedOf Word64 = Int64
+
+  signed = fromIntegral
+  {-# INLINE signed #-}
diff --git a/src/HaskellWorks/Data/Int/Unsigned.hs b/src/HaskellWorks/Data/Int/Unsigned.hs
new file mode 100644
--- /dev/null
+++ b/src/HaskellWorks/Data/Int/Unsigned.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE TypeFamilies #-}
+
+module HaskellWorks.Data.Int.Unsigned
+  ( Unsigned(..)
+  ) where
+
+import Data.Int
+import Data.Word
+
+class Unsigned a where
+  type UnsignedOf a
+
+  -- | Cast the value to a larger size.
+  --
+  -- This is safer to use than 'Prelude.fromIntegral'.
+  unsigned :: a -> UnsignedOf a
+
+instance Unsigned Int8 where
+  type UnsignedOf Int8 = Word8
+
+  unsigned = fromIntegral
+  {-# INLINE unsigned #-}
+
+instance Unsigned Int16 where
+  type UnsignedOf Int16 = Word16
+
+  unsigned = fromIntegral
+  {-# INLINE unsigned #-}
+
+instance Unsigned Int32 where
+  type UnsignedOf Int32 = Word32
+
+  unsigned = fromIntegral
+  {-# INLINE unsigned #-}
+
+instance Unsigned Int64 where
+  type UnsignedOf Int64 = Word64
+
+  unsigned = fromIntegral
+  {-# INLINE unsigned #-}
diff --git a/src/HaskellWorks/Data/Int/Widen.hs b/src/HaskellWorks/Data/Int/Widen.hs
--- a/src/HaskellWorks/Data/Int/Widen.hs
+++ b/src/HaskellWorks/Data/Int/Widen.hs
@@ -1,8 +1,100 @@
+{-# LANGUAGE MultiParamTypeClasses #-}
+
 module HaskellWorks.Data.Int.Widen
   ( module X
+  , Widen(..)
   ) where
 
-import HaskellWorks.Data.Int.Widen.Widen8  as X
+import Data.Int
+import Data.Word
+
 import HaskellWorks.Data.Int.Widen.Widen16 as X
 import HaskellWorks.Data.Int.Widen.Widen32 as X
 import HaskellWorks.Data.Int.Widen.Widen64 as X
+import HaskellWorks.Data.Int.Widen.Widen8  as X
+
+class Widen a b where
+  -- | Cast the value to a larger size.
+  --
+  -- This is safer to use than 'Prelude.fromIntegral'.
+  widen :: a -> b
+
+instance Widen Int8 Int8 where
+  widen = id
+  {-# INLINE widen #-}
+
+instance Widen Int8 Int16 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Int8 Int32 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Int8 Int64 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Int16 Int16 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Int16 Int32 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Int16 Int64 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Int32 Int32 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Int32 Int64 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Int64 Int64 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word8 Word8 where
+  widen = id
+  {-# INLINE widen #-}
+
+instance Widen Word8 Word16 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word8 Word32 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word8 Word64 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word16 Word16 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word16 Word32 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word16 Word64 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word32 Word32 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word32 Word64 where
+  widen = fromIntegral
+  {-# INLINE widen #-}
+
+instance Widen Word64 Word64 where
+  widen = fromIntegral
+  {-# INLINE widen #-}