moved Hashed into Class module

Author: andrewthad

Data/Hashable.hs

@@ -70,18 +70,8 @@ module Data.Hashable
     , unhashed
     ) where
 
-import Data.String (IsString(..))
-import Data.Typeable (Typeable)
 import Data.Hashable.Class
 
-#if !(MIN_VERSION_base(4,8,0))
-import Data.Foldable (Foldable(foldr))
-#endif
-
-#if MIN_VERSION_base(4,9,0)
-import Data.Functor.Classes (Eq1(..),Ord1(..),Show1(..),showsUnaryWith)
-#endif
-
 #ifdef GENERICS
 import Data.Hashable.Generic ()
 #endif
@@ -220,55 +210,3 @@ import Data.Hashable.Generic ()
 -- >     hashWithSalt s (Months n) = s `hashWithSalt`
 -- >                                 (2::Int) `hashWithSalt` n
 
--- | A hashable value along with the result of the 'hash' function.
-data Hashed a = Hashed a {-# UNPACK #-} !Int
-  deriving (Typeable)
-
--- | Wrap a hashable value, caching the 'hash' function result.
-hashed :: Hashable a => a -> Hashed a
-hashed a = Hashed a (hash a)
-
--- | Unwrap hashed value.
-unhashed :: Hashed a -> a
-unhashed (Hashed a _) = a
-
--- | Uses precomputed hash to detect inequality faster
-instance Eq a => Eq (Hashed a) where
-  Hashed a ha == Hashed b hb = ha == hb && a == b
-
-instance Ord a => Ord (Hashed a) where
-  Hashed a _ `compare` Hashed b _ = a `compare` b
-
-instance Show a => Show (Hashed a) where
-  showsPrec d (Hashed a _) = showParen (d > 10) $
-    showString "hashed" . showChar ' ' . showsPrec 11 a
-
-instance Hashable (Hashed a) where
-  hashWithSalt = defaultHashWithSalt
-  hash (Hashed _ h) = h
-
--- This instance is a little unsettling. It is unusal for
--- 'liftHashWithSalt' to ignore its first argument when a
--- value is actually available for it to work on.
-instance Hashable1 Hashed where
-  liftHashWithSalt _ s (Hashed _ h) = defaultHashWithSalt s h
-
-instance (IsString a, Hashable a) => IsString (Hashed a) where
-  fromString s = let r = fromString s in Hashed r (hash r)
-
-instance Foldable Hashed where
-  foldr f acc (Hashed a _) = f a acc
-
--- instances for @Data.Functor.Classes@ higher rank typeclasses
--- in base-4.9 and onward.
-#if MIN_VERSION_base(4,9,0)
-instance Eq1 Hashed where
-  liftEq f (Hashed a ha) (Hashed b hb) = ha == hb && f a b
-
-instance Ord1 Hashed where
-  liftCompare f (Hashed a _) (Hashed b _) = f a b
-
-instance Show1 Hashed where
-  liftShowsPrec sp _ d (Hashed a _) = showsUnaryWith sp "hashed" d a
-#endif
-

Data/Hashable/Class.hs

@@ -46,6 +46,10 @@ module Data.Hashable.Class
     , hashWithSalt1
     , hashWithSalt2
     , defaultLiftHashWithSalt
+    -- * Caching hashes
+    , Hashed
+    , hashed
+    , unhashed
     ) where
 
 import Control.Applicative (Const(..))
@@ -148,12 +152,15 @@ import GHC.Exts (Word(..))
 #if MIN_VERSION_base(4,9,0)
 import qualified Data.List.NonEmpty as NE
 import Data.Semigroup
+import Data.Functor.Classes (Eq1(..),Ord1(..),Show1(..),showsUnaryWith)
 
 import Data.Functor.Compose (Compose(..))
 import qualified Data.Functor.Product as FP
 import qualified Data.Functor.Sum as FS
 #endif
 
+import Data.String (IsString(..))
+
 #include "MachDeps.h"
 
 infixl 0 `hashWithSalt`
@@ -799,4 +806,56 @@ instance (Hashable1 f, Hashable1 g, Hashable a) => Hashable (FS.Sum f g a) where
     hashWithSalt = hashWithSalt1
 #endif
 
+-- | A hashable value along with the result of the 'hash' function.
+data Hashed a = Hashed a {-# UNPACK #-} !Int
+  deriving (Typeable)
+
+-- | Wrap a hashable value, caching the 'hash' function result.
+hashed :: Hashable a => a -> Hashed a
+hashed a = Hashed a (hash a)
+
+-- | Unwrap hashed value.
+unhashed :: Hashed a -> a
+unhashed (Hashed a _) = a
+
+-- | Uses precomputed hash to detect inequality faster
+instance Eq a => Eq (Hashed a) where
+  Hashed a ha == Hashed b hb = ha == hb && a == b
+
+instance Ord a => Ord (Hashed a) where
+  Hashed a _ `compare` Hashed b _ = a `compare` b
+
+instance Show a => Show (Hashed a) where
+  showsPrec d (Hashed a _) = showParen (d > 10) $
+    showString "hashed" . showChar ' ' . showsPrec 11 a
+
+instance Hashable (Hashed a) where
+  hashWithSalt = defaultHashWithSalt
+  hash (Hashed _ h) = h
+
+-- This instance is a little unsettling. It is unusal for
+-- 'liftHashWithSalt' to ignore its first argument when a
+-- value is actually available for it to work on.
+instance Hashable1 Hashed where
+  liftHashWithSalt _ s (Hashed _ h) = defaultHashWithSalt s h
+
+instance (IsString a, Hashable a) => IsString (Hashed a) where
+  fromString s = let r = fromString s in Hashed r (hash r)
+
+instance Foldable Hashed where
+  foldr f acc (Hashed a _) = f a acc
+
+-- instances for @Data.Functor.Classes@ higher rank typeclasses
+-- in base-4.9 and onward.
+#if MIN_VERSION_base(4,9,0)
+instance Eq1 Hashed where
+  liftEq f (Hashed a ha) (Hashed b hb) = ha == hb && f a b
+
+instance Ord1 Hashed where
+  liftCompare f (Hashed a _) (Hashed b _) = f a b
+
+instance Show1 Hashed where
+  liftShowsPrec sp _ d (Hashed a _) = showsUnaryWith sp "hashed" d a
+#endif
+