Hi Alex, thanks for your efforts and the update. I have a few questions about promise-chan if you have a moment.
Firstly, why provide promise-chan rather than requiring (chan (buffers/promise)). The buffer provides the promise semantics and we don't similarly have sliding-chan, dropping-chan, etc. Is this an effort to delineate channels with promise-buffers from the vanilla variety? Secondly, I've perhaps mistakenly considered channels more as a conduit between processes rather than a replacement for single assignment message passing. I get the value of using a channel and the core.async state machine for achieving promise-like semantics in a non-blocking way, and I can achieve that for a single consumer with a normal channel, the rub is this new buffer allows repeated consumption of a single value, and my previous understanding of channel semantics 'a channel will return nil when it is closed after some number of takes' no longer holds in all cases, because a promise-buffer is never exhausted. Practically I'm sure I'll always be aware of the buffer-flavour of a channel that I'm using, but now we have a variety of channels for which many channel operations do not make sense, i.e.: (async/go (prn "result" (async/<! (async/into [] some-chan))) Am I right in suggesting a promise-channel is not really a channel, it's a promise masquerading as a channel because of the value of having the state machine as the mechanism of resolving assignment. This is clearly a welcome addition, perhaps my understanding of channel semantics needs an upgrade. On Thursday, October 29, 2015 at 10:06:41 AM UTC+13, Alex Miller wrote: > > I am happy to announce a long-overdue core.async release. > > Dependency info: [org.clojure/core.async "0.2.371"] > > There are a few new features in this release: > > 1) *promise-chan* is a function that returns a new kind of channel (with > a custom buffer) with promise semantics. Specifically, channels make a > one-time transition to having a deliverable value. *promise-chan* takes > an optional transducer, and an optional exception-handler (like chan). A > promise channel can take exactly one value that consumers will receive. > Once full, puts complete but val is dropped (no transfer). > Consumers will block until either a value is placed in the channel or the > channel is closed (and nil will be delivered). > > 2) *offer!* and *poll!* are two new non-blocking functions available on > channels. > > offer! puts a val into a channel if it can do so immediately and will > never block. Returns true if offer succeeds. > poll! takes a val from a channel if it can do so immediately and will > never block. Return a value if successful, nil otherwise. > > All changes: > > - ASYNC-103 <http://dev.clojure.org/jira/browse/ASYNC-103> - NEW > promise-chan > - ASYNC-104 <http://dev.clojure.org/jira/browse/ASYNC-104> - NEW > non-blocking offer!, poll! > - ASYNC-124 <http://dev.clojure.org/jira/browse/ASYNC-124> - dispatch > multiple pending takers resulting from expanding transducer > - ASYNC-101 <http://dev.clojure.org/jira/browse/ASYNC-101> - > async/reduce now respects reduced > - ASYNC-112 <http://dev.clojure.org/jira/browse/ASYNC-112> - replace > "transformer" with "transducer" in deprecation messages > - ASYNC-6 <http://dev.clojure.org/jira/browse/ASYNC-6> - alts! docs > updated to explicitly state ports is a vector > - Support (try (catch :default)) in CLJS exception handling > - Use cljs.test > - Updated tools.analyzer.jvm version (and other upstream deps) - fixes > various analyzer errors > > > -- 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.
