Zlib decompression with leftovers.

Leftovers.ipynb

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   "source": [
    "{-# LANGUAGE OverloadedStrings #-}\n",
    "\n",
    "import qualified Codec.Compression.Zlib          as Z\n",
    "import qualified Codec.Compression.Zlib.Internal as ZI\n",
    "import qualified Data.ByteString                 as B\n",
    "import qualified Data.ByteString.Lazy            as L"
   ]
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    {
     "data": {
      "text/plain": [
       "(\"hello\",\"hi\")"
      ]
     },
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   "source": [
    "import qualified Control.Monad.ST.Lazy as ST\n",
    "\n",
    "ch = Z.compress \"hello\"\n",
    "input = ch `L.append` \"hi\"\n",
    "\n",
    "run :: Monad m => ZI.DecompressStream m -> L.ByteString -> m (B.ByteString, L.ByteString)\n",
    "run _                                   \"\"    = return (\"\",\"\")\n",
    "run (ZI.DecompressInputRequired supply) input = do\n",
    "    let (c:cs) =  L.toChunks input\n",
    "    let cs'    =  L.fromChunks cs\n",
    "    supplied   <- supply c\n",
    "    case supplied of\n",
    "        ZI.DecompressOutputAvailable output next -> do\n",
    "            next' <- next\n",
    "            (rest, remainder) <- run next' cs'\n",
    "            return (B.append output rest, remainder)\n",
    "        _ -> run supplied cs'\n",
    "run (ZI.DecompressStreamEnd remainder) input =\n",
    "    return (\"\", L.fromStrict remainder `L.append` input)\n",
    "run (ZI.DecompressStreamError err)     _     =\n",
    "    error $ show err\n",
    "\n",
    "decompress :: L.ByteString -> (B.ByteString, L.ByteString)\n",
    "decompress lbs = let\n",
    "    decompressor = ZI.decompressST ZI.zlibFormat ZI.defaultDecompressParams\n",
    "    in ST.runST $ run decompressor lbs\n",
    "\n",
    "decompress input"
   ]
  }
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