Attempt at prob 11 from 99 Haskell probs

prob11_runlength.hs

import Data.List (group)

data RunLength a = Single a | Multiple Int a deriving (Show, Eq)

encodeModified :: Eq a => [a] -> [RunLength a]
encodeModified = map runLength . group
    where runLength [x] = Single x
          runLength xs@(x:_) = Multiple (length xs) x