haskell-Crypto: fix build on GHC 7.4.1

http://anonscm.debian.org/cgi-bin/darcsweb.cgi?r=pkg-haskell/haskell-crypto;a=filediff;h=20120213034652-b2814-0019a3f92e453e9be86166d6c1f1bc0dad6e4d12.gz;f=patches/class-constraints.diff

svn path=/nixpkgs/trunk/; revision=32808

pkgs/development/libraries/haskell/Crypto/class-constraints.diff

@@ -0,0 +1,27 @@
+--- a/Data/Digest/SHA2.hs
++++ b/Data/Digest/SHA2.hs
+@@ -106,7 +106,7 @@
+ data Hash384 = Hash384 !Word64 !Word64 !Word64 !Word64 !Word64 !Word64 deriving (Eq, Ord)
+ data Hash224 = Hash224 !Word32 !Word32 !Word32 !Word32 !Word32 !Word32 !Word32 deriving (Eq, Ord)
+ 
+-instance (Integral a) => Show (Hash8 a) where
++instance (Integral a, Show a) => Show (Hash8 a) where
+  showsPrec _ (Hash8 a b c d e f g h) =
+   (showHex a) . (' ':) .
+   (showHex b) . (' ':) .
+@@ -146,7 +146,7 @@
+      where
+       bs = bitSize (head r)
+ 
+-instance (Integral h, Bits h) => Hash (Hash8 h) where
++instance (Integral h, Bits h, Show h) => Hash (Hash8 h) where
+   toOctets (Hash8 x0 x1 x2 x3 x4 x5 x6 x7) = bitsToOctets =<< [x0, x1, x2, x3, x4, x5, x6, x7]
+ 
+ instance Hash Hash384 where
+@@ -282,4 +282,4 @@
+ 
+ -- Test with:
+ -- ghc -no-recomp -O --make Data/Digest/SHA2.hs -main-is Data.Digest.SHA2.moduleTest -o moduleTest && ./moduleTest && rm moduleTest
+-moduleTest = runTestTT test_sha2
+\ No newline at end of file
++moduleTest = runTestTT test_sha2

pkgs/development/libraries/haskell/Crypto/default.nix

@@ -7,6 +7,7 @@ cabal.mkDerivation (self: {
   isLibrary = true;
   isExecutable = true;
   buildDepends = [ HUnit QuickCheck random ];
+  patches = [ ./class-constraints.diff ];
   meta = {
     description = "Collects together existing Haskell cryptographic functions into a package";
     license = "unknown";