Because it's Node-JS environment, and that can be the same for any async Javascript, you never wanna call sync operations (like sync ajax) because they block everything...
I was noticing that is a non-issue at all in Java world, since you can always read blocking into the predicate, for example: (filter (comp <!! my-chan-pred)) But in Javascript that's not possible since it can't support read blocking. --- Wilker Lúcio http://about.me/wilkerlucio/bio Woboinc Consultant +55 81 82556600 On Sun, Sep 21, 2014 at 8:50 PM, Leon Grapenthin <grapenthinl...@gmail.com> wrote: > 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> 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 >>> >> >> -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
