On Sat, Jun 29, 2013 at 5:27 PM, Cedric Greevey <cgree...@gmail.com> wrote:
> > On Sat, Jun 29, 2013 at 8:21 PM, Ben Wolfson <wolf...@gmail.com> wrote: > >> On Sat, Jun 29, 2013 at 5:07 PM, Brandon Bloom <brandon.d.bl...@gmail.com >> > wrote: >> >>> > Can anyone explain the relationship between swap! and reset! ? >>> >>> swap! is for "CAS" >>> >>> See: http://en.wikipedia.org/wiki/Compare-and-swap >>> >>> >> How so? No comparison is done (unless it's done in the supplied function, >> which is entirely up to the user of swap!). There's a separate >> compare-and-set! function for atoms. >> > > Er, swap! is basically > > (loop [] > (let [x @a y (f x)] > (if (compare-and-set! a x y) > y > (recur)))) > > though it actually calls a .swap method of the Atom object that has > equivalent semantics. > > The fact that swap! can be implemented with compare-and-set! doesn't make it enlightening (or even correct) to say that swap! is CAS, especially since compare-and-swap as explicated by the linked wikipedia page is actually compare-and-set! in Clojure terms (there's no transformation by a function and it's not unconditional). -- Ben Wolfson "Human kind has used its intelligence to vary the flavour of drinks, which may be sweet, aromatic, fermented or spirit-based. ... Family and social life also offer numerous other occasions to consume drinks for pleasure." [Larousse, "Drink" entry] -- -- 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/groups/opt_out.
