CODEWITHSUNDEEP
haskell
Alain O'Dea
Alain O'Dea

Reputation: 21686

How do I convert Data.ByteString.Char8 to Data.ByteString.Lazy for use in Data.Binary.Get?

I am in the midst of converting a package from using GHC.IO.Handle for networking to Network.Connection.Connection. One of the pain points is the number of places where Data.ByteString.Lazy.ByteString is being changed to Data.ByteString.Char8.ByteString.

An example function is:

import qualified Data.ByteString.Lazy as BL

-- gets the size of the frame
-- the bytestring should be at least 7 bytes long, otherwise this method will fail
peekFrameSize :: BL.ByteString -> PayloadSize
peekFrameSize = runGet f
  where
    f = do
      void $ getWord8 -- 1 byte
      void $ (get :: Get ChannelID) -- 2 bytes
      get :: Get PayloadSize -- 4 bytes

How do I convert Data.ByteString.Char8.ByteString to Data.ByteString.Lazy.ByteString for use in Data.Binary.Get?

Upvotes: 5

Views: 647

Answers (1)

Thomas M. DuBuisson
Thomas M. DuBuisson

Reputation: 64740

First of all, Data.ByteString.Char8 is a module, not a type. Same with Data.ByteString.Lazy. That said, and assuming the obvious, then notice that Data.ByteString.Char8.ByteString is actually a re-export of Data.ByteString.ByteString. So all you need is the fromStrict function mentioned by Mikail Glushenkov.

Upvotes: 4

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