word count

wc.hs

module Main where

import qualified Data.Map  as Map
import qualified Data.List as List
import qualified Data.Ord  as Ord

main :: IO ()
main = interact $ prettyPrint . toSortedList . counts . List.words


counts :: [String] -> Map.Map String Int
counts = foldr increment Map.empty

increment :: (Integral i) => String -> Map.Map String i -> Map.Map String i
increment s = Map.insertWith (+) s 1 

toSortedList :: (Ord i) => Map.Map String i -> [(String, i)]
toSortedList m = List.sortBy (Ord.comparing snd) $ Map.toList m

prettyPrint :: (Show i) => [(String, i)] -> String
prettyPrint = foldr addLine ""
    where addLine elem result = result ++ "\n" ++ (fst elem) ++ ": " ++ (show $ snd elem)