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Add instances for Integer and Ratio a
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@bos
bos committed May 10, 2011
1 parent 7fb69a9 commit 3fa360e
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Expand Up @@ -42,6 +42,7 @@ import Data.Bits (bitSize, shiftL, shiftR, xor)
import Data.Int (Int8, Int16, Int32, Int64)
import Data.Word (Word, Word8, Word16, Word32, Word64)
import Data.List (foldl')
import Data.Ratio (Ratio, denominator, numerator)
import qualified Data.ByteString as B
import qualified Data.ByteString.Internal as B
import qualified Data.ByteString.Unsafe as B
Expand Down Expand Up @@ -142,6 +143,13 @@ instance Hashable Word64 where
| bitSize (undefined :: Int) == 64 = fromIntegral n
| otherwise = fromIntegral (n `xor` (n `shiftR` 32))

instance Hashable Integer where hash = fromIntegral

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@tibbe

tibbe May 11, 2011

Does this really lead to good mixing of all bits in the Integer for Integers larger than maxBound :: Int? The fromIntegral call eventually calls toInt#

toInt# :: Integer -> Int#
toInt# (S# i)   = i
toInt# (J# s d) = integer2Int# s d

which calls integer2Int#

integer2Int# :: Int# -> ByteArray# -> Int#
integer2Int# s d = if s ==# 0#
                       then 0#
                       else let !v = indexIntArray# d 0# in
                            if s <# 0#
                               then negateInt# v
                               else v
instance (Integral a, Hashable a) => Hashable (Ratio a) where
hash a = hash (numerator a) `hashWithSalt` denominator a
{-# SPECIALIZE hash :: Ratio Integer -> Int #-}
hashWithSalt s a = s `hashWithSalt` numerator a `hashWithSalt` denominator a
{-# SPECIALIZE hashWithSalt :: Int -> Ratio Integer -> Int #-}

instance Hashable Float where
hash x
| isIEEE x =
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