Hashable for attributes

Author: jeffreyrosenbluth

lucid-svg.cabal

@@ -23,6 +23,7 @@ library
   build-depends:       base                  >= 4.5   && < 4.10,
                        blaze-builder         >= 0.4   && < 0.5,
                        bytestring            >= 0.10  && < 0.11,
+                       hashable             >= 1.1   && < 1.3,
                        text                  >= 0.11  && < 1.3,
                        unordered-containers  >= 0.2 && < 0.2.7
   hs-source-dirs:      src

src/Lucid/Svg/Core.hs

@@ -36,6 +36,7 @@ import qualified Blaze.ByteString.Builder as BB
 import qualified Blaze.ByteString.Builder.Html.Utf8 as BB
 import qualified Data.ByteString.Lazy as LB
 import           Data.ByteString.Lazy (ByteString)
+import           Data.Hashable (Hashable(..))
 import           Data.HashMap.Strict (HashMap)
 import qualified Data.HashMap.Strict as M
 import           Data.Monoid
@@ -51,6 +52,9 @@ import qualified Data.Text.Lazy.Encoding as LT
 data Attribute = Attribute !Text !Text
   deriving (Show,Eq)
 
+instance Hashable Attribute where
+  hashWithSalt salt (Attribute a b) = salt `hashWithSalt` a `hashWithSalt` b
+
 -- | Type of an SVG element.
 newtype Element = Element (HashMap Text Text -> Builder)