Question

I have a function f :: ByteString -> String, and need a Sink ByteString (ResourceT IO).
How do I get this?

Unfortunately, the docs were not very helpful…

Answer 1

I’m not sure why you need anything to do with resourceT in this conduit.

In order to return it all in one big string composed from all the little bytestrings, you’ll have to accumulate pieces for awhile, then return it a the end.

fSink :: Monad m => Sink ByteString m String
fSink = go []
  where
    go accum = do
      x <- await
      case x of
        Nothing -> return . f . B.concat . reverse $ accum
        Just x' -> go (x':accum)