Our candidate programming problem, implemented in Haskell

hamming.hs

import Data.List

normalizedScore :: String -> String -> Float
normalizedScore a b = fromIntegral (numSimilar a b) / fromIntegral (length a)

numSimilar :: String -> String -> Int
numSimilar a b = sum $ map fromEnum $ zipWith (==) a b

slice :: Int -> Int -> [a] -> [a]
slice from to xs = take (to - from + 1) (drop from xs)

slices :: Int -> [a] -> [[a]]
slices l xs = [slice a (a+l-1) xs | a <- [0 .. length xs - l]]

nbest :: Int -> String -> String -> [(Float, String)]
nbest n a b = take n $ reverse $ sort $ map (\x -> (normalizedScore a x, x)) $ slices (length a) b

was able to remove the similarity function and replace it with fromEnum