Give UUID an IsString instance

Author: jessekempf

uuid-types/Data/UUID/Types/Internal.hs

@@ -56,6 +56,9 @@ import           Data.Data
 import           Data.Functor                     ((<$>))
 import           Data.Hashable
 import           Data.List                        (elemIndices)
+import           Data.Maybe                       (fromMaybe)
+import           Data.Semigroup                   ((<>))
+import qualified Data.String                      as S (IsString (..))
 import           Foreign.Ptr                      (Ptr)
 
 import           Foreign.Storable
@@ -79,6 +82,10 @@ import           System.Random
 --  <http://tools.ietf.org/html/rfc4122 RFC 4122>.
 data UUID = UUID {-# UNPACK #-} !Word64 {-# UNPACK #-} !Word64
           deriving (Eq, Ord, Typeable)
+
+instance S.IsString UUID where
+    fromString str = fromMaybe (error ("'" <> str <> "' is not a valid UUID")) $ fromString str
+
 {-
     Prior to uuid-types-1.0.4:
          !Word32 !Word32 !Word32 !Word32