On Sat, Jan 7, 2012 at 8:45 PM, Grant
So I want to take the sha-1 of the file contents prefixed with a string containing the file size (similar to how git hashes files). Is there a nice way to compose this without having to create two sources against the same file?
Thanks, Grant
I can think of three approaches that should work: 1. Create a Sink which "forks" its input to two other Sinks (similar to &&& for Arrow). It would have a type signature like: Sink a m b -> Sink a m c -> Sink a m (b, c) 2. Create a specialized Sink that will wrap a single sink and add the byte count of the input stream, eg: Sink ByteString m a -> Sink ByteString m (Int, a) 3. Use a Conduit that will simply update some mutable variable. I think (1) is the most generally useful, though (3) would be the easiest to put together. If you want help implementing any of these approaches, let me know. Michael