[commit: ghc] master: Define `Data` instance for `Natural` type (#9818) (4bf055c)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/4bf055c70d07b98be1e7749e0306e406dfbbc006/ghc

>---------------------------------------------------------------

commit 4bf055c70d07b98be1e7749e0306e406dfbbc006
Author: Herbert Valerio Riedel <hvr at gnu.org>
Date:   Tue Nov 25 23:23:08 2014 +0100

    Define `Data` instance for `Natural` type (#9818)
    
    This follows the same style as the other integral `Data` instances
    defined in the `Data.Data` module.
    
    Reviewed By: ekmett
    
    Differential Revision: https://phabricator.haskell.org/D526


>---------------------------------------------------------------

4bf055c70d07b98be1e7749e0306e406dfbbc006
 libraries/base/GHC/Natural.hs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/libraries/base/GHC/Natural.hs b/libraries/base/GHC/Natural.hs
index e9b37b1..221bc31 100644
--- a/libraries/base/GHC/Natural.hs
+++ b/libraries/base/GHC/Natural.hs
@@ -67,6 +67,7 @@ import GHC.Enum
 import GHC.List
 
 import Data.Bits
+import Data.Data
 
 default ()
 
@@ -588,3 +589,16 @@ naturalToWordMaybe (Natural i)
   where
     maxw = toInteger (maxBound :: Word)
 #endif
+
+-- This follows the same style as the other integral 'Data' instances
+-- defined in "Data.Data"
+naturalType :: DataType
+naturalType = mkIntType "Numeric.Natural.Natural"
+
+instance Data Natural where
+  toConstr x = mkIntegralConstr naturalType x
+  gunfold _ z c = case constrRep c of
+                    (IntConstr x) -> z (fromIntegral x)
+                    _ -> error $ "Data.Data.gunfold: Constructor " ++ show c
+                                 ++ " is not of type Natural"
+  dataTypeOf _ = naturalType