dev-haskell/cond: fix build failure against ghc-7.6

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

dev-haskell/cond/cond-0.4.0.1.ebuild

@@ -7,7 +7,7 @@ EAPI=5
 # ebuild generated by hackport 0.3.9999
 
 CABAL_FEATURES="lib profile haddock hoogle hscolour"
-inherit haskell-cabal
+inherit base haskell-cabal
 
 DESCRIPTION="Basic conditional and boolean operators with monadic variants."
 HOMEPAGE="https://github.com/kallisti-dev/cond"
@@ -21,3 +21,5 @@ IUSE=""
 RDEPEND=">=dev-lang/ghc-6.10.4:="
 DEPEND="${RDEPEND}
 		>=dev-haskell/cabal-1.6"
+
+PATCHES=("${FILESDIR}"/${P}-ghc-7.6.patch)

dev-haskell/cond/files/cond-0.4.0.1-ghc-7.6.patch

@@ -0,0 +1,27 @@
+Fixes the following build failure:
+
+[1 of 2] Compiling Data.Algebra.Boolean ( src/Data/Algebra/Boolean.hs, dist/build/Data/Algebra/Boolean.o )
+
+src/Data/Algebra/Boolean.hs:125:20:
+    Could not deduce (Num a) arising from the literal `0'
+    from the context (Bits a)
+      bound by the instance declaration
+      at src/Data/Algebra/Boolean.hs:123:10-38
+    Possible fix:
+      add (Num a) to the context of the instance declaration
+    In the first argument of `Bitwise', namely `0'
+    In the expression: Bitwise 0
+    In an equation for `false': false = Bitwise 0
+diff --git a/src/Data/Algebra/Boolean.hs b/src/Data/Algebra/Boolean.hs
+index 46481fc..0cae046 100644
+--- a/src/Data/Algebra/Boolean.hs
++++ b/src/Data/Algebra/Boolean.hs
+@@ -120,7 +120,7 @@ newtype Bitwise a = Bitwise {getBits :: a}
+                   deriving (Num, Bits, Eq, Ord, Bounded, Enum, Show, Read, Real,
+                             Integral, Typeable, Data, Ix, Storable, PrintfArg)
+
+-instance Bits a => Boolean (Bitwise a) where
++instance (Bits a, Num a) => Boolean (Bitwise a) where
+   true   = not false 
+   false  = Bitwise 0 
+   not    = Bitwise . complement . getBits