Scrub e-mail addresses from HTML page

scrub.hs

module Main where

import System.Environment (getArgs)
import System.Exit (exitFailure)
import Data.List (intercalate)

-- Scrub automata
scrub :: String -> [String]
scrub [] = []
scrub ('m':'a':'i':'l':'t':'o':':':rest) =
    email : scrub rest'
  where
    (email, rest') = break (== '\"') rest
scrub (x:xs) = scrub xs

main :: IO ()
main = do
     args <- getArgs
     case args of
          [] -> do
             putStrLn "Please specify file to scrub."
             exitFailure

          (file:_) -> do
            fileData <- readFile file
            putStrLn (intercalate "," (scrub fileData))

Build with ghc scrub.hs -o scrub