If you're putting data into a channel, why not just add the transducer to the channel creation so it is applied as you pull values off the channel?
Sean On Sep 21, 2014, at 3:01 PM, Wilker <wilkerlu...@gmail.com> wrote: > Hi guys, > > I'm playing with transducers here, and trying out stuff just for fun, there > is something that I'm kind stuck on how to approach. I understand the great > abstraction that transducers provide over don't carrying about the input > source type, but I'm struggling to deal with async operations into my > pipeline. > > For example, I'm working with Node.JS async API's for file system operations, > I want to stick with the async versions since I don't wanna block the event > loop of Node. > > So, let's say I have a source with ["dir", "other"] and I wanna create an > operation that will simple filter which paths exists, are directories, and > then list the `ls` of each remaining entry. > > So, I first created "channel returning" functions for the Node operations, > I'll not put the code here because I don't think it's really relevant here, > just consider that I have them. > > So, my pipeline would start looking something like this: > > (comp (filter exists?) > (filter is-dir?) > (mapcat readdir)) > > Of course, this doesn't works... Because `exists?`, `is-dir?` and `readdir`, > all of them return channels, so the filter would always pass since a channel > is always a valid value... The same applies to mapcat, it would try to concat > into a channel... > > This is making me notice some barrier to be able to compose async operations > with regular operations. > > Maybe would be possible to "sign" somehow operations to make then run async? > > The only viable option that I've found is with pipeline-async, which accepts > an async function, but that doesn't composes with the other operations (map, > filter, drop-while...) > > Is there already a solution to that? Or maybe I'm just doing it wrong and > there is a better way to handle those cases? > > I would love to know how you guys are handling those kind of situations. > > Thanks.
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