Data.Hash

Combinators for building fast hashing functions.

Based on the BuzHash algorithm by Robert Uzgalis (see, e.g. "Hashing concepts and the Java programming language" at http://www.serve.net/buz/hash.adt/java.000.html)

The Hash type

data Hash

A 64-bit hash

Instances

Bounded Hash

Eq Hash

Ord Hash

Show Hash

asWord64 :: Hash -> Word64

Basic combinators

hashWord8 :: Word8 -> Hash

combine :: Hash -> Hash -> Hash

h1 `combine` h2 combines hashes h1 and h2 into a new hash.

It is used to generate hash functions for complex types. For example:

hashPair :: (Hashable a, Hashable b) => (a,b) -> Hash
hashPair (a,b) = hash a `combine` hash b

Derived combinators

hashWord16 :: Word16 -> Hash

hashWord32 :: Word32 -> Hash

hashWord64 :: Word64 -> Hash

hashInt :: Int -> Hash

hashStorable :: Storable a => a -> Hash

Observe that, unlike the other functions in this module, hashStorable is machine-dependent (the computed hash depends on endianness, etc.).

hashFoldable :: (Foldable t, Hashable a) => t a -> Hash

The Hashable class

class Hashable a where

Methods

hash :: a -> Hash

Instances

Hashable Bool

Hashable Char

Hashable Double

Hashable Float

Hashable Int

Hashable Int8

Hashable Int16

Hashable Int32

Hashable Int64

Hashable Integer

Hashable Word

Hashable Word8

Hashable Word16

Hashable Word32

Hashable Word64

Hashable ()

Hashable a => Hashable [a]

(Integral a, Hashable a) => Hashable (Ratio a)

Hashable a => Hashable (Maybe a)

(Hashable a, Hashable b) => Hashable (Either a b)

(Hashable a, Hashable b) => Hashable (a, b)

(Hashable a, Hashable b, Hashable c) => Hashable (a, b, c)

(Hashable a, Hashable b, Hashable c, Hashable d) => Hashable (a, b, c, d)

Rolling hashes

module Data.Hash.Rolling