BFA Assembler in Haskell

bfasm.hs

import Data.Char  (isSpace)
import Data.Maybe (listToMaybe, fromMaybe)

maybeRead :: Read a => String -> Maybe a
maybeRead = fmap fst . listToMaybe . reads

parseLine :: String -> (Int, String)
parseLine = uncurry ((,) . fromMaybe 1 . maybeRead) . break isSpace

makeLine :: (Int, String) -> String
makeLine = concat . uncurry replicate

main = interact $ (++ "\n")
                . filter (`elem` "+-><.,[]")
                . unlines
                . map (makeLine . parseLine . dropWhile isSpace)
                . lines