Memory hog + Stack overflow

mem.hs

module Main where

import System.IO
import qualified Data.Map as M
import qualified Data.Text.Lazy as T
import qualified Data.Text.Lazy.IO as T
import Data.List (foldl')
-- maybe Data.Text.Lazy  maybe ByteString
(+++) = T.append

main = do
    inh <- openFile "doubles.txt" ReadMode
    document <- T.hGetContents inh
    outh <- openFile "dict.txt" WriteMode

    let counts = mainLoop''  document M.empty
    let excsPairs = M.assocs counts
    let excsStr = T.concat $ map (\(w, count) -> w +++ T.pack " :: " +++ T.pack (show count) +++T.pack "\n") excsPairs
    T.hPutStr outh excsStr
    hClose inh
    hClose outh
    
-- mainLoop' ::  T.Text -> M.Map T.Text Int ->  M.Map T.Text Int
mainLoop' m line = updateMapForWords m (T.words line)
mainLoop'' document m  = foldl' mainLoop' m (T.lines document)

-- mainLoop :: Handle -> M.Map String Int -> IO (M.Map String Int)
mainLoop inh counts = do
    inEof <- hIsEOF inh
    if inEof
        then return counts
        else do
            ws <- (T.hGetLine inh >>= \inStr -> return $ T.words inStr)
            mainLoop inh $ updateMapForWords counts ws

-- - updateMapForWords :: [String] -> M.Map String Int -> M.Map String Int
updateMapForWords counts ws = 
    foldr (\w m -> M.alter updateCount w m) counts ws
    where 
    updateCount (Just !c) = Just $ c + 1
    updateCount Nothing = Just 1

I put up another gist, but all this forking is confusing https://gist.github.com/3151613