Haskell Map Reduce

map_reduce.hs

import Data.Char
import Data.List
groupWord:: [(String,Integer)] -> [[(String,Integer)]]
sortLT:: (String, Integer) -> (String, Integer) -> Ordering

filterWord = filter (all isAlphaNum) . words

mapWordCounter = map (\w -> (w,1))

sortLT (w1,_) (w2,_)
    | w1 < w2 = LT
    | w1 > w2 = GT
    | w1 == w2 = EQ

sortMap = sortBy sortLT

groupWord  = groupBy (\(w1,_) (w2,_) -> w1 == w2) 

mapGroupWord mapGroupList= map (\((w,1):xs) -> (w, map (\(w,v) -> v) ((w,1):xs))) (groupWord$sortMap mapGroupList)

reduceGroupWord = map (\(w,listCounter)  -> (w,sum(listCounter)))

mapReduce = reduceGroupWord.mapGroupWord.mapWordCounter.filterWord