Using Google's CityHash hash functions for strings

Google's CityHash hash functions are optimized for hashing strings, but are not meant to be cryptographically secure. CityHash is ideal for implementing a hash table dealing with strings. We will use it in this recipe to produce both 64-bit and 128-bit digests.

Getting ready

Install the cityhash package from Cabal as follows:

$ cabal install cityhash

How to do it…

1. Import the relevant packages as follows:

   import Data.Digest.CityHash
   import Data.ByteString.Char8 (pack)
   import Data.Word (Word64)
   import Data.LargeWord (Word128)

2. Test the various hashing function on an input string using the following code snippet:

   main = do
    (pack str) (1 :: Word128)  let str = "cityhash"
     print $ cityHash64 (pack str)
     print $ cityHash64WithSeed (pack str) (1 :: Word64)
     print $ cityHash64WithSeed (pack str) (2 :: Word64)
     print $ cityHash128 (pack str)
     print $ cityHash128WithSeed
     print $ cityHash128WithSeed (pack str) (2 :: Word128)

3. Display the output as follows...