Combining hPutBuilder + primMapByteStringBounded unsafe with reuse? #203
Description
The program below will hang if the iteration count (command-line argument) is sufficiently high, 253 loops or more (the default of 10 shows it working initially):
{-# LANGUAGE BlockArguments #-}
{-# LANGUAGE TupleSections #-}
module Main (main) where
import Data.ByteString.Char8 as C8 (pack)
import Data.ByteString.Builder as B
import Data.ByteString.Builder.Prim as P
import Data.ByteString.Lazy as B
import Data.ByteString.Lazy.Char8 as L8
import Data.List as L
import System.IO as S
import System.Environment as S
main = do
count >>= B.hPutBuilder S.stdout . loop
where
count :: IO Int
count = maybe 10 read . fmap fst . L.uncons <$> S.getArgs
loop n
| n > 0 =
B.string8 "iteration "
<> B.intDec n
<> B.char8 ' '
<> B.word8 0x22
<> P.primMapByteStringBounded enc
do C8.pack "\\Escape me\192\"please\""
<> B.word8 0x22
<> B.char8 '\n'
<> loop (n-1)
| otherwise = mempty
enc =
P.condB
do (\w -> w >= 0x20 && w < 0x7f)
do P.condB
do (\w -> w /= 0x22 && w /= 0x5c)
do toB P.word8
do fstUnit >$< esc >*< toB P.word8
do P.condB
do (> 99)
do fstUnit >$< esc >*< P.word8Dec
do P.condB
do (> 9)
do fstUnit . fstUnit
>$< esc >*< zero >*< P.word8Dec
do fstUnit . fstUnit . fstUnit
>$< esc >*< zero >*< zero >*< P.word8Dec
toB = P.liftFixedToBounded
esc = toB $ const 0x5c >$< P.word8
fstUnit = ((), )
zero = toB $ const 0x30 >$< P.word8