Why would you want the the predicates and readdir to return channels? On Monday, September 22, 2014 12:14:27 AM UTC+2, Wilker wrote: > > Just an add, > > I was thinking if we could have something like a "deref" running during > the transducers, in order to enable value unwrapping (that way we could > handle channels/values in same fashion). I understand that is complicated > maybe because overhead, and also more tricky into JS world were you can't > deref a channel into a sync fashion. > > But the point remains, there is way to seamlessly handle async and sync > operations using the same transducers? Or something like it. > > Best regards. > > --- > Wilker Lúcio > http://about.me/wilkerlucio/bio > Woboinc Consultant > +55 81 82556600 > > On Sun, Sep 21, 2014 at 7:01 PM, Wilker <wilke...@gmail.com <javascript:>> > 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. >> >> --- >> Wilker Lúcio >> http://about.me/wilkerlucio/bio >> Woboinc Consultant >> +55 81 82556600 >> > >
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