But yes, we should probably at least put a note in the docs for map< stating "returning nil from the mapping function can result in undefined behavior". Or add an assert somewhere perhaps.
Timothy On Mon, Apr 7, 2014 at 9:36 AM, James Reeves <ja...@booleanknot.com> wrote: > This looks like a bug to me. A lot of the internal core.async functions > rely on nil values indicating the channel is closed. > > - James > > > On 7 April 2014 16:26, Alejandro Ciniglio <skiae...@gmail.com> wrote: > >> Using core.async, I've understood the convention to be that if you take >> nil from a channel, that channel is closed. This seems to hold for most >> cases, but I've found a corner case when using map< that lets you pull nil >> from a channel that is not closed. >> >> (def a (chan)) >> (def c (map< seq a)) >> (go (prn (<! c))) >> (>!! a []) >> ; => nil nil ;; [one nil is printed, one is returned] >> (go (prn (<! c))) >> (>!! a [1]) >> ; => nil (1) >> >> This can be chained as well (e.g. (map< identity (map< seq a)) ), and >> nils just flow through. >> >> From looking at the implementation, it's apparent that this happens >> because the function application of map happens when taking from the output >> channel so nil is not technically on the channel, (unless it flows through >> to another map). >> >> Is this a bug or is my mental model of nil => closed incorrect? >> >> Thanks, >> Alejandro >> >> -- >> 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. > -- "One of the main causes of the fall of the Roman Empire was that-lacking zero-they had no way to indicate successful termination of their C programs." (Robert Firth) -- 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.
