decode.enable1.stm.hs

-- decode.enable1.stm.hs

-- inspired by a word guessing game
-- https://www.futurelearn.com/courses/functional-programming-haskell/1/steps/116475

import qualified Data.ByteString.Lazy as BL
import qualified Data.ByteString as B
import Data.Binary.Get
import Data.Word
 
-- readStem :: Get (Int, Int, Data.ByteString.Internal.ByteString)
readStem = do
  prefixLength <- fmap fromIntegral getWord8
  suffixLength <- fmap fromIntegral getWord8
  suffix <- getByteString suffixLength
  return (prefixLength, suffixLength, suffix)
 -- https://wiki.haskell.org/Dealing_with_binary_data

readStems = do
	empty <- isEmpty
	if empty then return []
	else do 	v <- readStem
			rest <- readStems
			return (v : rest)

mkWords stems = scanl accum B.empty stems where
	accum acc (pl,sl,suf) = B.concat [(B.take pl acc), suf]

main = do
	let fname = "enable1.stm"
	input <- BL.readFile fname 
	let stems = runGet readStems input
	let words = mkWords stems
	mapM_ B.putStrLn  words