You can build this up using the >=< operator[1] in stm-conduit, something like: eitherSrc :: MonadResourceBase m => Source (ResourceT m) a -> Source (ResourceT m) b -> Source (ResourceT m) (Either a b) eitherSrc src1 src2 = do join $ lift $ Data.Conduit.mapOutput Left src1 >=< Data.Conduit.mapOutput Right src2 I think this can be generalized to work with more base monads with some tweaks to (>=<). [1] http://haddocks.fpcomplete.com/fp/7.4.2/20130704-120/stm-conduit/Data-Condui... On Fri, Aug 23, 2013 at 11:32 AM, Erik de Castro Lopo wrote:

Hi all

Using the Conduit library is it possible to write the function:

eitherSrc :: MonadResource m => Source m a -> Source m b -> Source m (Either a b)

which combines two sources into new output source such that data being produced aysnchronously by the original two sources will be returned as either a Left or Right of tne new source?

If so, how?

Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/

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