utils/Binary.hs

    {-# LANGUAGE CPP, MagicHash, UnboxedTuples #-}
    {-# LANGUAGE FlexibleInstances #-}
    {-# LANGUAGE PolyKinds #-}
    {-# LANGUAGE ScopedTypeVariables #-}
    {-# LANGUAGE GADTs #-}

    {-# OPTIONS_GHC -O -funbox-strict-fields #-}
    -- We always optimise this, otherwise performance of a non-optimised
    -- compiler is severely affected

    --
    -- (c) The University of Glasgow 2002-2006
    --
    -- Binary I/O library, with special tweaks for GHC
    --
    -- Based on the nhc98 Binary library, which is copyright
    -- (c) Malcolm Wallace and Colin Runciman, University of York, 1998.
    -- Under the terms of the license for that software, we must tell you
    -- where you can obtain the original version of the Binary library, namely
    --     http://www.cs.york.ac.uk/fp/nhc98/

    module Binary
      ( {-type-}  Bin,
        {-class-} Binary(..),
        {-type-}  BinHandle,
        SymbolTable, Dictionary,

       openBinMem,
    --   closeBin,

       seekBin,
       seekBy,
       tellBin,
       castBin,
       isEOFBin,
       withBinBuffer,

       writeBinMem,
       readBinMem,

       putAt, getAt,

       -- * For writing instances
       putByte,
       getByte,

       -- * Lazy Binary I/O
       lazyGet,
       lazyPut,

       -- * User data
       UserData(..), getUserData, setUserData,
       newReadState, newWriteState,
       putDictionary, getDictionary, putFS,
      ) where

    #include "HsVersions.h"

    -- The *host* architecture version:
    #include "../includes/MachDeps.h"

    import {-# SOURCE #-} Name (Name)
    import FastString
    import Panic
    import UniqFM
    import FastMutInt
    import Fingerprint
    import BasicTypes
    import SrcLoc

    import Foreign
    import Data.Array
    import Data.ByteString (ByteString)
    import qualified Data.ByteString.Internal as BS
    import qualified Data.ByteString.Unsafe   as BS
    import Data.IORef
    import Data.Char                ( ord, chr )
    import Data.Time
    #if MIN_VERSION_base(4,10,0)
    import Type.Reflection
    import Type.Reflection.Unsafe
    import Data.Kind (Type)
    import GHC.Exts (RuntimeRep(..), VecCount(..), VecElem(..))
    #else
    import Data.Typeable
    #endif
    import Control.Monad            ( when )
    import System.IO as IO
    import System.IO.Unsafe         ( unsafeInterleaveIO )
    import System.IO.Error          ( mkIOError, eofErrorType )
    import GHC.Real                 ( Ratio(..) )
    import GHC.Serialized

    type BinArray = ForeignPtr Word8

    ---------------------------------------------------------------
    -- BinHandle
    ---------------------------------------------------------------

    data BinHandle
      = BinMem {                     -- binary data stored in an unboxed array
         bh_usr :: UserData,         -- sigh, need parameterized modules :-)
         _off_r :: !FastMutInt,      -- the current offset
         _sz_r  :: !FastMutInt,      -- size of the array (cached)
         _arr_r :: !(IORef BinArray) -- the array (bounds: (0,size-1))
        }
            -- XXX: should really store a "high water mark" for dumping out
            -- the binary data to a file.

    getUserData :: BinHandle -> UserData
    getUserData bh = bh_usr bh

    setUserData :: BinHandle -> UserData -> BinHandle
    setUserData bh us = bh { bh_usr = us }

    -- | Get access to the underlying buffer.
    --
    -- It is quite important that no references to the 'ByteString' leak out of the
    -- continuation lest terrible things happen.
    withBinBuffer :: BinHandle -> (ByteString -> IO a) -> IO a
    withBinBuffer (BinMem _ ix_r _ arr_r) action = do
      arr <- readIORef arr_r
      ix <- readFastMutInt ix_r
      withForeignPtr arr $ \ptr ->
        BS.unsafePackCStringLen (castPtr ptr, ix) >>= action

    ---------------------------------------------------------------
    -- Bin
    ---------------------------------------------------------------

    newtype Bin a = BinPtr Int
      deriving (Eq, Ord, Show, Bounded)

    castBin :: Bin a -> Bin b
    castBin (BinPtr i) = BinPtr i

    ---------------------------------------------------------------
    -- class Binary
    ---------------------------------------------------------------

    class Binary a where
        put_   :: BinHandle -> a -> IO ()
        put    :: BinHandle -> a -> IO (Bin a)
        get    :: BinHandle -> IO a

        -- define one of put_, put.  Use of put_ is recommended because it
        -- is more likely that tail-calls can kick in, and we rarely need the
        -- position return value.
        put_ bh a = do _ <- put bh a; return ()
        put bh a  = do p <- tellBin bh; put_ bh a; return p

    putAt  :: Binary a => BinHandle -> Bin a -> a -> IO ()
    putAt bh p x = do seekBin bh p; put_ bh x; return ()

    getAt  :: Binary a => BinHandle -> Bin a -> IO a
    getAt bh p = do seekBin bh p; get bh

    openBinMem :: Int -> IO BinHandle
    openBinMem size
     | size <= 0 = error "Data.Binary.openBinMem: size must be >= 0"
     | otherwise = do
       arr <- mallocForeignPtrBytes size
       arr_r <- newIORef arr
       ix_r <- newFastMutInt
       writeFastMutInt ix_r 0
       sz_r <- newFastMutInt
       writeFastMutInt sz_r size
       return (BinMem noUserData ix_r sz_r arr_r)

    tellBin :: BinHandle -> IO (Bin a)
    tellBin (BinMem _ r _ _) = do ix <- readFastMutInt r; return (BinPtr ix)

    seekBin :: BinHandle -> Bin a -> IO ()
    seekBin h@(BinMem _ ix_r sz_r _) (BinPtr p) = do
      sz <- readFastMutInt sz_r
      if (p >= sz)
            then do expandBin h p; writeFastMutInt ix_r p
            else writeFastMutInt ix_r p

    seekBy :: BinHandle -> Int -> IO ()
    seekBy h@(BinMem _ ix_r sz_r _) off = do
      sz <- readFastMutInt sz_r
      ix <- readFastMutInt ix_r
      let ix' = ix + off
      if (ix' >= sz)
            then do expandBin h ix'; writeFastMutInt ix_r ix'
            else writeFastMutInt ix_r ix'

    isEOFBin :: BinHandle -> IO Bool
    isEOFBin (BinMem _ ix_r sz_r _) = do
      ix <- readFastMutInt ix_r
      sz <- readFastMutInt sz_r
      return (ix >= sz)

    writeBinMem :: BinHandle -> FilePath -> IO ()
    writeBinMem (BinMem _ ix_r _ arr_r) fn = do
      h <- openBinaryFile fn WriteMode
      arr <- readIORef arr_r
      ix  <- readFastMutInt ix_r
      withForeignPtr arr $ \p -> hPutBuf h p ix
      hClose h

    readBinMem :: FilePath -> IO BinHandle
    -- Return a BinHandle with a totally undefined State
    readBinMem filename = do
      h <- openBinaryFile filename ReadMode
      filesize' <- hFileSize h
      let filesize = fromIntegral filesize'
      arr <- mallocForeignPtrBytes filesize
      count <- withForeignPtr arr $ \p -> hGetBuf h p filesize
      when (count /= filesize) $
           error ("Binary.readBinMem: only read " ++ show count ++ " bytes")
      hClose h
      arr_r <- newIORef arr
      ix_r <- newFastMutInt
      writeFastMutInt ix_r 0
      sz_r <- newFastMutInt
      writeFastMutInt sz_r filesize
      return (BinMem noUserData ix_r sz_r arr_r)

    -- expand the size of the array to include a specified offset
    expandBin :: BinHandle -> Int -> IO ()
    expandBin (BinMem _ _ sz_r arr_r) off = do
       sz <- readFastMutInt sz_r
       let sz' = head (dropWhile (<= off) (iterate (* 2) sz))
       arr <- readIORef arr_r
       arr' <- mallocForeignPtrBytes sz'
       withForeignPtr arr $ \old ->
         withForeignPtr arr' $ \new ->
           copyBytes new old sz
       writeFastMutInt sz_r sz'
       writeIORef arr_r arr'

    -- -----------------------------------------------------------------------------
    -- Low-level reading/writing of bytes

    putPrim :: BinHandle -> Int -> (Ptr Word8 -> IO ()) -> IO ()
    putPrim h@(BinMem _ ix_r sz_r arr_r) size f = do
      ix <- readFastMutInt ix_r
      sz <- readFastMutInt sz_r
      when (ix + size > sz) $
        expandBin h (ix + size)
      arr <- readIORef arr_r
      withForeignPtr arr $ \op -> f (op `plusPtr` ix)
      writeFastMutInt ix_r (ix + size)

    getPrim :: BinHandle -> Int -> (Ptr Word8 -> IO a) -> IO a
    getPrim (BinMem _ ix_r sz_r arr_r) size f = do
      ix <- readFastMutInt ix_r
      sz <- readFastMutInt sz_r
      when (ix + size > sz) $
          ioError (mkIOError eofErrorType "Data.Binary.getPrim" Nothing Nothing)
      arr <- readIORef arr_r
      w <- withForeignPtr arr $ \op -> f (op `plusPtr` ix)
      writeFastMutInt ix_r (ix + size)
      return w

    putWord8 :: BinHandle -> Word8 -> IO ()
    putWord8 h w = putPrim h 1 (\op -> poke op w)

    getWord8 :: BinHandle -> IO Word8
    getWord8 h = getPrim h 1 peek

    putWord16 :: BinHandle -> Word16 -> IO ()
    putWord16 h w = putPrim h 2 (\op -> do
      pokeElemOff op 0 (fromIntegral (w `shiftR` 8))
      pokeElemOff op 1 (fromIntegral (w .&. 0xFF))
      )

    getWord16 :: BinHandle -> IO Word16
    getWord16 h = getPrim h 2 (\op -> do
      w0 <- fromIntegral <$> peekElemOff op 0
      w1 <- fromIntegral <$> peekElemOff op 1
      return $! w0 `shiftL` 8 .|. w1
      )

    putWord32 :: BinHandle -> Word32 -> IO ()
    putWord32 h w = putPrim h 4 (\op -> do
      pokeElemOff op 0 (fromIntegral (w `shiftR` 24))
      pokeElemOff op 1 (fromIntegral ((w `shiftR` 16) .&. 0xFF))
      pokeElemOff op 2 (fromIntegral ((w `shiftR` 8) .&. 0xFF))
      pokeElemOff op 3 (fromIntegral (w .&. 0xFF))
      )

    getWord32 :: BinHandle -> IO Word32
    getWord32 h = getPrim h 4 (\op -> do
      w0 <- fromIntegral <$> peekElemOff op 0
      w1 <- fromIntegral <$> peekElemOff op 1
      w2 <- fromIntegral <$> peekElemOff op 2
      w3 <- fromIntegral <$> peekElemOff op 3

      return $! (w0 `shiftL` 24) .|.
                (w1 `shiftL` 16) .|.
                (w2 `shiftL` 8)  .|.
                w3
      )

    putWord64 :: BinHandle -> Word64 -> IO ()
    putWord64 h w = putPrim h 8 (\op -> do
      pokeElemOff op 0 (fromIntegral (w `shiftR` 56))
      pokeElemOff op 1 (fromIntegral ((w `shiftR` 48) .&. 0xFF))
      pokeElemOff op 2 (fromIntegral ((w `shiftR` 40) .&. 0xFF))
      pokeElemOff op 3 (fromIntegral ((w `shiftR` 32) .&. 0xFF))
      pokeElemOff op 4 (fromIntegral ((w `shiftR` 24) .&. 0xFF))
      pokeElemOff op 5 (fromIntegral ((w `shiftR` 16) .&. 0xFF))
      pokeElemOff op 6 (fromIntegral ((w `shiftR` 8) .&. 0xFF))
      pokeElemOff op 7 (fromIntegral (w .&. 0xFF))
      )

    getWord64 :: BinHandle -> IO Word64
    getWord64 h = getPrim h 8 (\op -> do
      w0 <- fromIntegral <$> peekElemOff op 0
      w1 <- fromIntegral <$> peekElemOff op 1
      w2 <- fromIntegral <$> peekElemOff op 2
      w3 <- fromIntegral <$> peekElemOff op 3
      w4 <- fromIntegral <$> peekElemOff op 4
      w5 <- fromIntegral <$> peekElemOff op 5
      w6 <- fromIntegral <$> peekElemOff op 6
      w7 <- fromIntegral <$> peekElemOff op 7

      return $! (w0 `shiftL` 56) .|.
                (w1 `shiftL` 48) .|.
                (w2 `shiftL` 40) .|.
                (w3 `shiftL` 32) .|.
                (w4 `shiftL` 24) .|.
                (w5 `shiftL` 16) .|.
                (w6 `shiftL` 8)  .|.
                w7
      )

    putByte :: BinHandle -> Word8 -> IO ()
    putByte bh w = putWord8 bh w

    getByte :: BinHandle -> IO Word8
    getByte h = getWord8 h

    -- -----------------------------------------------------------------------------
    -- Primitve Word writes

    instance Binary Word8 where
      put_ = putWord8
      get  = getWord8

    instance Binary Word16 where
      put_ h w = putWord16 h w
      get h = getWord16 h

    instance Binary Word32 where
      put_ h w = putWord32 h w
      get h = getWord32 h

    instance Binary Word64 where
      put_ h w = putWord64 h w
      get h = getWord64 h

    -- -----------------------------------------------------------------------------
    -- Primitve Int writes

    instance Binary Int8 where
      put_ h w = put_ h (fromIntegral w :: Word8)
      get h    = do w <- get h; return $! (fromIntegral (w::Word8))

    instance Binary Int16 where
      put_ h w = put_ h (fromIntegral w :: Word16)
      get h    = do w <- get h; return $! (fromIntegral (w::Word16))

    instance Binary Int32 where
      put_ h w = put_ h (fromIntegral w :: Word32)
      get h    = do w <- get h; return $! (fromIntegral (w::Word32))

    instance Binary Int64 where
      put_ h w = put_ h (fromIntegral w :: Word64)
      get h    = do w <- get h; return $! (fromIntegral (w::Word64))

    -- -----------------------------------------------------------------------------
    -- Instances for standard types

    instance Binary () where
        put_ _ () = return ()
        get  _    = return ()

    instance Binary Bool where
        put_ bh b = putByte bh (fromIntegral (fromEnum b))
        get  bh   = do x <- getWord8 bh; return $! (toEnum (fromIntegral x))

    instance Binary Char where
        put_  bh c = put_ bh (fromIntegral (ord c) :: Word32)
        get  bh   = do x <- get bh; return $! (chr (fromIntegral (x :: Word32)))

    instance Binary Int where
        put_ bh i = put_ bh (fromIntegral i :: Int64)
        get  bh = do
            x <- get bh
            return $! (fromIntegral (x :: Int64))

    instance Binary a => Binary [a] where
        put_ bh l = do
            let len = length l
            if (len < 0xff)
              then putByte bh (fromIntegral len :: Word8)
              else do putByte bh 0xff; put_ bh (fromIntegral len :: Word32)
            mapM_ (put_ bh) l
        get bh = do
            b <- getByte bh
            len <- if b == 0xff
                      then get bh
                      else return (fromIntegral b :: Word32)
            let loop 0 = return []
                loop n = do a <- get bh; as <- loop (n-1); return (a:as)
            loop len

    instance (Binary a, Binary b) => Binary (a,b) where
        put_ bh (a,b) = do put_ bh a; put_ bh b
        get bh        = do a <- get bh
                           b <- get bh
                           return (a,b)

    instance (Binary a, Binary b, Binary c) => Binary (a,b,c) where
        put_ bh (a,b,c) = do put_ bh a; put_ bh b; put_ bh c
        get bh          = do a <- get bh
                             b <- get bh
                             c <- get bh
                             return (a,b,c)

    instance (Binary a, Binary b, Binary c, Binary d) => Binary (a,b,c,d) where
        put_ bh (a,b,c,d) = do put_ bh a; put_ bh b; put_ bh c; put_ bh d
        get bh            = do a <- get bh
                               b <- get bh
                               c <- get bh
                               d <- get bh
                               return (a,b,c,d)

    instance (Binary a, Binary b, Binary c, Binary d, Binary e) => Binary (a,b,c,d, e) where
        put_ bh (a,b,c,d, e) = do put_ bh a; put_ bh b; put_ bh c; put_ bh d; put_ bh e;
        get bh               = do a <- get bh
                                  b <- get bh
                                  c <- get bh
                                  d <- get bh
                                  e <- get bh
                                  return (a,b,c,d,e)

    instance (Binary a, Binary b, Binary c, Binary d, Binary e, Binary f) => Binary (a,b,c,d, e, f) where
        put_ bh (a,b,c,d, e, f) = do put_ bh a; put_ bh b; put_ bh c; put_ bh d; put_ bh e; put_ bh f;
        get bh                  = do a <- get bh
                                     b <- get bh
                                     c <- get bh
                                     d <- get bh
                                     e <- get bh
                                     f <- get bh
                                     return (a,b,c,d,e,f)

    instance (Binary a, Binary b, Binary c, Binary d, Binary e, Binary f, Binary g) => Binary (a,b,c,d,e,f,g) where
        put_ bh (a,b,c,d,e,f,g) = do put_ bh a; put_ bh b; put_ bh c; put_ bh d; put_ bh e; put_ bh f; put_ bh g
        get bh                  = do a <- get bh
                                     b <- get bh
                                     c <- get bh
                                     d <- get bh
                                     e <- get bh
                                     f <- get bh
                                     g <- get bh
                                     return (a,b,c,d,e,f,g)

    instance Binary a => Binary (Maybe a) where
        put_ bh Nothing  = putByte bh 0
        put_ bh (Just a) = do putByte bh 1; put_ bh a
        get bh           = do h <- getWord8 bh
                              case h of
                                0 -> return Nothing
                                _ -> do x <- get bh; return (Just x)

    instance (Binary a, Binary b) => Binary (Either a b) where
        put_ bh (Left  a) = do putByte bh 0; put_ bh a
        put_ bh (Right b) = do putByte bh 1; put_ bh b
        get bh            = do h <- getWord8 bh
                               case h of
                                 0 -> do a <- get bh ; return (Left a)
                                 _ -> do b <- get bh ; return (Right b)

    instance Binary UTCTime where
        put_ bh u = do put_ bh (utctDay u)
                       put_ bh (utctDayTime u)
        get bh = do day <- get bh
                    dayTime <- get bh
                    return $ UTCTime { utctDay = day, utctDayTime = dayTime }

    instance Binary Day where
        put_ bh d = put_ bh (toModifiedJulianDay d)
        get bh = do i <- get bh
                    return $ ModifiedJulianDay { toModifiedJulianDay = i }

    instance Binary DiffTime where
        put_ bh dt = put_ bh (toRational dt)
        get bh = do r <- get bh
                    return $ fromRational r

    --to quote binary-0.3 on this code idea,
    --
    -- TODO  This instance is not architecture portable.  GMP stores numbers as
    -- arrays of machine sized words, so the byte format is not portable across
    -- architectures with different endianess and word size.
    --
    -- This makes it hard (impossible) to make an equivalent instance
    -- with code that is compilable with non-GHC.  Do we need any instance
    -- Binary Integer, and if so, does it have to be blazing fast?  Or can
    -- we just change this instance to be portable like the rest of the
    -- instances? (binary package has code to steal for that)
    --
    -- yes, we need Binary Integer and Binary Rational in basicTypes/Literal.hs

    instance Binary Integer where
        put_ bh i
          | i >= lo32 && i <= hi32 = do
              putWord8 bh 0
              put_ bh (fromIntegral i :: Int32)
          | otherwise = do
              putWord8 bh 1
              put_ bh (show i)
          where
            lo32 = fromIntegral (minBound :: Int32)
            hi32 = fromIntegral (maxBound :: Int32)

        get bh = do
          int_kind <- getWord8 bh
          case int_kind of
            0 -> fromIntegral <$> (get bh :: IO Int32)
            _ -> do str <- get bh
                    case reads str of
                      [(i, "")] -> return i
                      _ -> fail ("Binary integer: got " ++ show str)

        {-
        -- This code is currently commented out.
        -- See https://ghc.haskell.org/trac/ghc/ticket/3379#comment:10 for
        -- discussion.

        put_ bh (S# i#) = do putByte bh 0; put_ bh (I# i#)
        put_ bh (J# s# a#) = do
            putByte bh 1
            put_ bh (I# s#)
            let sz# = sizeofByteArray# a#  -- in *bytes*
            put_ bh (I# sz#)  -- in *bytes*
            putByteArray bh a# sz#

        get bh = do
            b <- getByte bh
            case b of
              0 -> do (I# i#) <- get bh
                      return (S# i#)
              _ -> do (I# s#) <- get bh
                      sz <- get bh
                      (BA a#) <- getByteArray bh sz
                      return (J# s# a#)

    putByteArray :: BinHandle -> ByteArray# -> Int# -> IO ()
    putByteArray bh a s# = loop 0#
      where loop n#
               | n# ==# s# = return ()
               | otherwise = do
                    putByte bh (indexByteArray a n#)
                    loop (n# +# 1#)

    getByteArray :: BinHandle -> Int -> IO ByteArray
    getByteArray bh (I# sz) = do
      (MBA arr) <- newByteArray sz
      let loop n
               | n ==# sz = return ()
               | otherwise = do
                    w <- getByte bh
                    writeByteArray arr n w
                    loop (n +# 1#)
      loop 0#
      freezeByteArray arr
        -}

    {-
    data ByteArray = BA ByteArray#
    data MBA = MBA (MutableByteArray# RealWorld)

    newByteArray :: Int# -> IO MBA
    newByteArray sz = IO $ \s ->
      case newByteArray# sz s of { (# s, arr #) ->
      (# s, MBA arr #) }

    freezeByteArray :: MutableByteArray# RealWorld -> IO ByteArray
    freezeByteArray arr = IO $ \s ->
      case unsafeFreezeByteArray# arr s of { (# s, arr #) ->
      (# s, BA arr #) }

    writeByteArray :: MutableByteArray# RealWorld -> Int# -> Word8 -> IO ()
    writeByteArray arr i (W8# w) = IO $ \s ->
      case writeWord8Array# arr i w s of { s ->
      (# s, () #) }

    indexByteArray :: ByteArray# -> Int# -> Word8
    indexByteArray a# n# = W8# (indexWord8Array# a# n#)

    -}
    instance (Binary a) => Binary (Ratio a) where
        put_ bh (a :% b) = do put_ bh a; put_ bh b
        get bh = do a <- get bh; b <- get bh; return (a :% b)

    instance Binary (Bin a) where
      put_ bh (BinPtr i) = put_ bh (fromIntegral i :: Int32)
      get bh = do i <- get bh; return (BinPtr (fromIntegral (i :: Int32)))

    -- -----------------------------------------------------------------------------
    -- Instances for Data.Typeable stuff

    #if MIN_VERSION_base(4,10,0)
    instance Binary TyCon where
        put_ bh tc = do
            put_ bh (tyConPackage tc)
            put_ bh (tyConModule tc)
            put_ bh (tyConName tc)
            put_ bh (tyConKindArgs tc)
            put_ bh (tyConKindRep tc)
        get bh =
            mkTyCon <$> get bh <*> get bh <*> get bh <*> get bh <*> get bh
    #else
    instance Binary TyCon where
        put_ bh tc = do
            put_ bh (tyConPackage tc)
            put_ bh (tyConModule tc)
            put_ bh (tyConName tc)
        get bh =
            mkTyCon3 <$> get bh <*> get bh <*> get bh
    #endif

    #if MIN_VERSION_base(4,10,0)
    instance Binary VecCount where
        put_ bh = putByte bh . fromIntegral . fromEnum
        get bh = toEnum . fromIntegral <$> getByte bh

    instance Binary VecElem where
        put_ bh = putByte bh . fromIntegral . fromEnum
        get bh = toEnum . fromIntegral <$> getByte bh

    instance Binary RuntimeRep where
        put_ bh (VecRep a b)    = putByte bh 0 >> put_ bh a >> put_ bh b
        put_ bh (TupleRep reps) = putByte bh 1 >> put_ bh reps
        put_ bh (SumRep reps)   = putByte bh 2 >> put_ bh reps
        put_ bh LiftedRep       = putByte bh 3
        put_ bh UnliftedRep     = putByte bh 4
        put_ bh IntRep          = putByte bh 5
        put_ bh WordRep         = putByte bh 6
        put_ bh Int64Rep        = putByte bh 7
        put_ bh Word64Rep       = putByte bh 8
        put_ bh AddrRep         = putByte bh 9
        put_ bh FloatRep        = putByte bh 10
        put_ bh DoubleRep       = putByte bh 11

        get bh = do
            tag <- getByte bh
            case tag of
              0  -> VecRep <$> get bh <*> get bh
              1  -> TupleRep <$> get bh
              2  -> SumRep <$> get bh
              3  -> pure LiftedRep
              4  -> pure UnliftedRep
              5  -> pure IntRep
              6  -> pure WordRep
              7  -> pure Int64Rep
              8  -> pure Word64Rep
              9  -> pure AddrRep
              10 -> pure FloatRep
              11 -> pure DoubleRep
              _  -> fail "Binary.putRuntimeRep: invalid tag"

    instance Binary KindRep where
        put_ bh (KindRepTyConApp tc k) = putByte bh 0 >> put_ bh tc >> put_ bh k
        put_ bh (KindRepVar bndr) = putByte bh 1 >> put_ bh bndr
        put_ bh (KindRepApp a b) = putByte bh 2 >> put_ bh a >> put_ bh b
        put_ bh (KindRepFun a b) = putByte bh 3 >> put_ bh a >> put_ bh b
        put_ bh (KindRepTYPE r) = putByte bh 4 >> put_ bh r
        put_ bh (KindRepTypeLit sort r) = putByte bh 5 >> put_ bh sort >> put_ bh r

        get bh = do
            tag <- getByte bh
            case tag of
              0 -> KindRepTyConApp <$> get bh <*> get bh
              1 -> KindRepVar <$> get bh
              2 -> KindRepApp <$> get bh <*> get bh
              3 -> KindRepFun <$> get bh <*> get bh
              4 -> KindRepTYPE <$> get bh
              5 -> KindRepTypeLit <$> get bh <*> get bh
              _ -> fail "Binary.putKindRep: invalid tag"

    instance Binary TypeLitSort where
        put_ bh TypeLitSymbol = putByte bh 0
        put_ bh TypeLitNat = putByte bh 1
        get bh = do
            tag <- getByte bh
            case tag of
              0 -> pure TypeLitSymbol
              1 -> pure TypeLitNat
              _ -> fail "Binary.putTypeLitSort: invalid tag"

    putTypeRep :: BinHandle -> TypeRep a -> IO ()
    -- Special handling for TYPE, (->), and RuntimeRep due to recursive kind
    -- relations.
    -- See Note [Mutually recursive representations of primitive types]
    putTypeRep bh rep
      | Just HRefl <- rep `eqTypeRep` (typeRep :: TypeRep Type)
      = put_ bh (0 :: Word8)
    putTypeRep bh (Con' con ks) = do
        put_ bh (1 :: Word8)
        put_ bh con
        put_ bh ks
    putTypeRep bh (App f x) = do
        put_ bh (2 :: Word8)
        putTypeRep bh f
        putTypeRep bh x
    putTypeRep bh (Fun arg res) = do
        put_ bh (3 :: Word8)
        putTypeRep bh arg
        putTypeRep bh res
    putTypeRep _ _ = fail "Binary.putTypeRep: Impossible"

    getSomeTypeRep :: BinHandle -> IO SomeTypeRep
    getSomeTypeRep bh = do
        tag <- get bh :: IO Word8
        case tag of
            0 -> return $ SomeTypeRep (typeRep :: TypeRep Type)
            1 -> do con <- get bh :: IO TyCon
                    ks <- get bh :: IO [SomeTypeRep]
                    return $ SomeTypeRep $ mkTrCon con ks

            2 -> do SomeTypeRep f <- getSomeTypeRep bh
                    SomeTypeRep x <- getSomeTypeRep bh
                    case typeRepKind f of
                      Fun arg res ->
                          case arg `eqTypeRep` typeRepKind x of
                            Just HRefl ->
                                case typeRepKind res `eqTypeRep` (typeRep :: TypeRep Type) of
                                  Just HRefl -> return $ SomeTypeRep $ mkTrApp f x
                                  _ -> failure "Kind mismatch in type application" []
                            _ -> failure "Kind mismatch in type application"
                                 [ "    Found argument of kind: " ++ show (typeRepKind x)
                                 , "    Where the constructor:  " ++ show f
                                 , "    Expects kind:           " ++ show arg
                                 ]
                      _ -> failure "Applied non-arrow"
                           [ "    Applied type: " ++ show f
                           , "    To argument:  " ++ show x
                           ]
            3 -> do SomeTypeRep arg <- getSomeTypeRep bh
                    SomeTypeRep res <- getSomeTypeRep bh
                    case typeRepKind arg `eqTypeRep` (typeRep :: TypeRep Type) of
                      Just HRefl ->
                          case typeRepKind res `eqTypeRep` (typeRep :: TypeRep Type) of
                            Just HRefl -> return $ SomeTypeRep $ Fun arg res
                            Nothing -> failure "Kind mismatch" []
                      _ -> failure "Kind mismatch" []
            _ -> failure "Invalid SomeTypeRep" []
      where
        failure description info =
            fail $ unlines $ [ "Binary.getSomeTypeRep: "++description ]
                          ++ map ("    "++) info

    instance Typeable a => Binary (TypeRep (a :: k)) where
        put_ = putTypeRep
        get bh = do
            SomeTypeRep rep <- getSomeTypeRep bh
            case rep `eqTypeRep` expected of
                Just HRefl -> pure rep
                Nothing    -> fail $ unlines
                                   [ "Binary: Type mismatch"
                                   , "    Deserialized type: " ++ show rep
                                   , "    Expected type:     " ++ show expected
                                   ]
         where expected = typeRep :: TypeRep a

    instance Binary SomeTypeRep where
        put_ bh (SomeTypeRep rep) = putTypeRep bh rep
        get = getSomeTypeRep
    #else
    instance Binary TypeRep where
        put_ bh type_rep = do
            let (ty_con, child_type_reps) = splitTyConApp type_rep
            put_ bh ty_con
            put_ bh child_type_reps
        get bh = do
            ty_con <- get bh
            child_type_reps <- get bh
            return (mkTyConApp ty_con child_type_reps)
    #endif

    -- -----------------------------------------------------------------------------
    -- Lazy reading/writing

    lazyPut :: Binary a => BinHandle -> a -> IO ()
    lazyPut bh a = do
        -- output the obj with a ptr to skip over it:
        pre_a <- tellBin bh
        put_ bh pre_a       -- save a slot for the ptr
        put_ bh a           -- dump the object
        q <- tellBin bh     -- q = ptr to after object
        putAt bh pre_a q    -- fill in slot before a with ptr to q
        seekBin bh q        -- finally carry on writing at q

    lazyGet :: Binary a => BinHandle -> IO a
    lazyGet bh = do
        p <- get bh -- a BinPtr
        p_a <- tellBin bh
        a <- unsafeInterleaveIO $ do
            -- NB: Use a fresh off_r variable in the child thread, for thread
            -- safety.
            off_r <- newFastMutInt
            getAt bh { _off_r = off_r } p_a
        seekBin bh p -- skip over the object for now
        return a

    -- -----------------------------------------------------------------------------
    -- UserData
    -- -----------------------------------------------------------------------------

    -- | Information we keep around during interface file
    -- serialization/deserialization. Namely we keep the functions for serializing
    -- and deserializing 'Name's and 'FastString's. We do this because we actually
    -- use serialization in two distinct settings,
    --
    -- * When serializing interface files themselves
    --
    -- * When computing the fingerprint of an IfaceDecl (which we computing by
    --   hashing its Binary serialization)
    --
    -- These two settings have different needs while serializing Names:
    --
    -- * Names in interface files are serialized via a symbol table (see Note
    --   [Symbol table representation of names] in BinIface).
    --
    -- * During fingerprinting a binding Name is serialized as the OccName and a
    --   non-binding Name is serialized as the fingerprint of the thing they
    --   represent. See Note [Fingerprinting IfaceDecls] for further discussion.
    --
    data UserData =
       UserData {
            -- for *deserialising* only:
            ud_get_name :: BinHandle -> IO Name,
            ud_get_fs   :: BinHandle -> IO FastString,

            -- for *serialising* only:
            ud_put_nonbinding_name :: BinHandle -> Name -> IO (),
            -- ^ serialize a non-binding 'Name' (e.g. a reference to another
            -- binding).
            ud_put_binding_name :: BinHandle -> Name -> IO (),
            -- ^ serialize a binding 'Name' (e.g. the name of an IfaceDecl)
            ud_put_fs   :: BinHandle -> FastString -> IO ()
       }

    newReadState :: (BinHandle -> IO Name)   -- ^ how to deserialize 'Name's
                 -> (BinHandle -> IO FastString)
                 -> UserData
    newReadState get_name get_fs
      = UserData { ud_get_name = get_name,
                   ud_get_fs   = get_fs,
                   ud_put_nonbinding_name = undef "put_nonbinding_name",
                   ud_put_binding_name    = undef "put_binding_name",
                   ud_put_fs   = undef "put_fs"
                 }

    newWriteState :: (BinHandle -> Name -> IO ())
                     -- ^ how to serialize non-binding 'Name's
                  -> (BinHandle -> Name -> IO ())
                     -- ^ how to serialize binding 'Name's
                  -> (BinHandle -> FastString -> IO ())
                  -> UserData
    newWriteState put_nonbinding_name put_binding_name put_fs
      = UserData { ud_get_name = undef "get_name",
                   ud_get_fs   = undef "get_fs",
                   ud_put_nonbinding_name = put_nonbinding_name,
                   ud_put_binding_name    = put_binding_name,
                   ud_put_fs   = put_fs
                 }

    noUserData :: a
    noUserData = undef "UserData"

    undef :: String -> a
    undef s = panic ("Binary.UserData: no " ++ s)

    ---------------------------------------------------------
    -- The Dictionary
    ---------------------------------------------------------

    type Dictionary = Array Int FastString -- The dictionary
                                           -- Should be 0-indexed

    putDictionary :: BinHandle -> Int -> UniqFM (Int,FastString) -> IO ()
    putDictionary bh sz dict = do
      put_ bh sz
      mapM_ (putFS bh) (elems (array (0,sz-1) (nonDetEltsUFM dict)))
        -- It's OK to use nonDetEltsUFM here because the elements have indices
        -- that array uses to create order

    getDictionary :: BinHandle -> IO Dictionary
    getDictionary bh = do
      sz <- get bh
      elems <- sequence (take sz (repeat (getFS bh)))
      return (listArray (0,sz-1) elems)

    ---------------------------------------------------------
    -- The Symbol Table
    ---------------------------------------------------------

    -- On disk, the symbol table is an array of IfExtName, when
    -- reading it in we turn it into a SymbolTable.

    type SymbolTable = Array Int Name

    ---------------------------------------------------------
    -- Reading and writing FastStrings
    ---------------------------------------------------------

    putFS :: BinHandle -> FastString -> IO ()
    putFS bh fs = putBS bh $ fastStringToByteString fs

    getFS :: BinHandle -> IO FastString
    getFS bh = do
      l  <- get bh :: IO Int
      getPrim bh l (\src -> pure $! mkFastStringBytes src l )

    putBS :: BinHandle -> ByteString -> IO ()
    putBS bh bs =
      BS.unsafeUseAsCStringLen bs $ \(ptr, l) -> do
        put_ bh l
        putPrim bh l (\op -> BS.memcpy op (castPtr ptr) l)

    getBS :: BinHandle -> IO ByteString
    getBS bh = do
      l <- get bh :: IO Int
      BS.create l $ \dest -> do
        getPrim bh l (\src -> BS.memcpy dest src l)

    instance Binary ByteString where
      put_ bh f = putBS bh f
      get bh = getBS bh

    instance Binary FastString where
      put_ bh f =
        case getUserData bh of
            UserData { ud_put_fs = put_fs } -> put_fs bh f

      get bh =
        case getUserData bh of
            UserData { ud_get_fs = get_fs } -> get_fs bh

    -- Here to avoid loop
    instance Binary LeftOrRight where
       put_ bh CLeft  = putByte bh 0
       put_ bh CRight = putByte bh 1

       get bh = do { h <- getByte bh
                   ; case h of
                       0 -> return CLeft
                       _ -> return CRight }

    instance Binary Fingerprint where
      put_ h (Fingerprint w1 w2) = do put_ h w1; put_ h w2
      get  h = do w1 <- get h; w2 <- get h; return (Fingerprint w1 w2)

    instance Binary FunctionOrData where
        put_ bh IsFunction = putByte bh 0
        put_ bh IsData     = putByte bh 1
        get bh = do
            h <- getByte bh
            case h of
              0 -> return IsFunction
              1 -> return IsData
              _ -> panic "Binary FunctionOrData"

    instance Binary TupleSort where
        put_ bh BoxedTuple      = putByte bh 0
        put_ bh UnboxedTuple    = putByte bh 1
        put_ bh ConstraintTuple = putByte bh 2
        get bh = do
          h <- getByte bh
          case h of
            0 -> do return BoxedTuple
            1 -> do return UnboxedTuple
            _ -> do return ConstraintTuple

    instance Binary Activation where
        put_ bh NeverActive = do
                putByte bh 0
        put_ bh AlwaysActive = do
                putByte bh 1
        put_ bh (ActiveBefore src aa) = do
                putByte bh 2
                put_ bh src
                put_ bh aa
        put_ bh (ActiveAfter src ab) = do
                putByte bh 3
                put_ bh src
                put_ bh ab
        get bh = do
                h <- getByte bh
                case h of
                  0 -> do return NeverActive
                  1 -> do return AlwaysActive
                  2 -> do src <- get bh
                          aa <- get bh
                          return (ActiveBefore src aa)
                  _ -> do src <- get bh
                          ab <- get bh
                          return (ActiveAfter src ab)

    instance Binary InlinePragma where
        put_ bh (InlinePragma s a b c d) = do
                put_ bh s
                put_ bh a
                put_ bh b
                put_ bh c
                put_ bh d

        get bh = do
               s <- get bh
               a <- get bh
               b <- get bh
               c <- get bh
               d <- get bh
               return (InlinePragma s a b c d)

    instance Binary RuleMatchInfo where
        put_ bh FunLike = putByte bh 0
        put_ bh ConLike = putByte bh 1
        get bh = do
                h <- getByte bh
                if h == 1 then return ConLike
                          else return FunLike

    instance Binary InlineSpec where
        put_ bh EmptyInlineSpec = putByte bh 0
        put_ bh Inline          = putByte bh 1
        put_ bh Inlinable       = putByte bh 2
        put_ bh NoInline        = putByte bh 3

        get bh = do h <- getByte bh
                    case h of
                      0 -> return EmptyInlineSpec
                      1 -> return Inline
                      2 -> return Inlinable
                      _ -> return NoInline

    instance Binary RecFlag where
        put_ bh Recursive = do
                putByte bh 0
        put_ bh NonRecursive = do
                putByte bh 1
        get bh = do
                h <- getByte bh
                case h of
                  0 -> do return Recursive
                  _ -> do return NonRecursive

    instance Binary OverlapMode where
        put_ bh (NoOverlap    s) = putByte bh 0 >> put_ bh s
        put_ bh (Overlaps     s) = putByte bh 1 >> put_ bh s
        put_ bh (Incoherent   s) = putByte bh 2 >> put_ bh s
        put_ bh (Overlapping  s) = putByte bh 3 >> put_ bh s
        put_ bh (Overlappable s) = putByte bh 4 >> put_ bh s
        get bh = do
            h <- getByte bh
            case h of
                0 -> (get bh) >>= \s -> return $ NoOverlap s
                1 -> (get bh) >>= \s -> return $ Overlaps s
                2 -> (get bh) >>= \s -> return $ Incoherent s
                3 -> (get bh) >>= \s -> return $ Overlapping s
                4 -> (get bh) >>= \s -> return $ Overlappable s
                _ -> panic ("get OverlapMode" ++ show h)

    instance Binary OverlapFlag where
        put_ bh flag = do put_ bh (overlapMode flag)
                          put_ bh (isSafeOverlap flag)
        get bh = do
            h <- get bh
            b <- get bh
            return OverlapFlag { overlapMode = h, isSafeOverlap = b }

    instance Binary FixityDirection where
        put_ bh InfixL = do
                putByte bh 0
        put_ bh InfixR = do
                putByte bh 1
        put_ bh InfixN = do
                putByte bh 2
        get bh = do
                h <- getByte bh
                case h of
                  0 -> do return InfixL
                  1 -> do return InfixR
                  _ -> do return InfixN

    instance Binary Fixity where
        put_ bh (Fixity src aa ab) = do
                put_ bh src
                put_ bh aa
                put_ bh ab
        get bh = do
              src <- get bh
              aa <- get bh
              ab <- get bh
              return (Fixity src aa ab)

    instance Binary WarningTxt where
        put_ bh (WarningTxt s w) = do
                putByte bh 0
                put_ bh s
                put_ bh w
        put_ bh (DeprecatedTxt s d) = do
                putByte bh 1
                put_ bh s
                put_ bh d

        get bh = do
                h <- getByte bh
                case h of
                  0 -> do s <- get bh
                          w <- get bh
                          return (WarningTxt s w)
                  _ -> do s <- get bh
                          d <- get bh
                          return (DeprecatedTxt s d)

    instance Binary StringLiteral where
      put_ bh (StringLiteral st fs) = do
                put_ bh st
                put_ bh fs
      get bh = do
                st <- get bh
                fs <- get bh
                return (StringLiteral st fs)

    instance Binary a => Binary (GenLocated SrcSpan a) where
        put_ bh (L l x) = do
                put_ bh l
                put_ bh x

        get bh = do
                l <- get bh
                x <- get bh
                return (L l x)

    instance Binary SrcSpan where
      put_ bh (RealSrcSpan ss) = do
              putByte bh 0
              put_ bh (srcSpanFile ss)
              put_ bh (srcSpanStartLine ss)
              put_ bh (srcSpanStartCol ss)
              put_ bh (srcSpanEndLine ss)
              put_ bh (srcSpanEndCol ss)

      put_ bh (UnhelpfulSpan s) = do
              putByte bh 1
              put_ bh s

      get bh = do
              h <- getByte bh
              case h of
                0 -> do f <- get bh
                        sl <- get bh
                        sc <- get bh
                        el <- get bh
                        ec <- get bh
                        return (mkSrcSpan (mkSrcLoc f sl sc)
                                          (mkSrcLoc f el ec))
                _ -> do s <- get bh
                        return (UnhelpfulSpan s)

    instance Binary Serialized where
        put_ bh (Serialized the_type bytes) = do
            put_ bh the_type
            put_ bh bytes
        get bh = do
            the_type <- get bh
            bytes <- get bh
            return (Serialized the_type bytes)

    instance Binary SourceText where
      put_ bh NoSourceText = putByte bh 0
      put_ bh (SourceText s) = do
            putByte bh 1
            put_ bh s

      get bh = do
        h <- getByte bh
        case h of
          0 -> return NoSourceText
          1 -> do
            s <- get bh
            return (SourceText s)
          _ -> panic $ "Binary SourceText:" ++ show h