Wait isn't this caching? https://github.com/clojure/clojure/blob/master/src/clj/clojure/core_deftype.clj#L480
On Thu Jan 22 2015 at 8:44:09 PM Bobby Eickhoff <beickh...@gmail.com> wrote: > Clojure isn't doing the caching. The JVM is doing the caching. In this > case, Clojure just has mechanical sympathy for how the JVM operates. > > > On Thursday, January 22, 2015 at 11:10:56 PM UTC-5, Michael Blume wrote: > >> It sounds like basically dispatch is fast because we bothered to make it >> fast (by caching) and satisfies? is slow because we didn't. Is it worth >> throwing caching at satisfies? to make it fast or should satisfies? just >> not be on the critical path for Clojure code? >> >> (To give a motivating example, satisfies? is on the critical path for >> honeysql and will be until this pull is merged: https://github.com/ >> jkk/honeysql/pull/38) >> >> >> On Thu Jan 22 2015 at 5:52:13 PM Ghadi Shayban <gsha...@gmail.com> wrote: >> >>> Protocol call sites build an inline cache to optimize dispatch. The >>> benchmark is running many times and reaping benefit from the cache. >>> satisfies? looks up the object's class in the protocol's implementation >>> map [1], and the benchmark is stressing this. You'll see that code checks >>> if the protocol has the backing interface first, then checks for the >>> object's class, then if necessary walks up the superclass chain. >>> >>> [1] https://github.com/clojure/clojure/blob/master/ >>> src/clj/clojure/core_deftype.clj#L507-L516 >>> >>> >>> >>> On Thursday, January 22, 2015 at 8:36:23 PM UTC-5, Michael Blume wrote: >>> >>>> Extends seems to be defeated by superclassing. ie: >>>> >>>> (extends? my-protocol (class {})) => false >>>> >>>> because my-protocol is extended to IPersistentMap and (class {}) isn't >>>> IPersistentMap it's PersistentArrayMap (which implements IPersistentMap but >>>> extends? doesn't care) >>>> >>>> On Thu Jan 22 2015 at 5:28:30 PM Timothy Baldridge <tbald...@gmail.com> >>>> wrote: >>>> >>> The logic of extends? is much simpler, so try that. IIRC it's something >>>>> like "extends? returns true if any method on the protocol is implemented >>>>> by >>>>> x", "satisfies? returns true if all methods of a protocol are implemented >>>>> by x". >>>>> >>>>> The docs don't seem to give much help here, so play with it in the >>>>> repl a bit. >>>>> >>>>> Timothy >>>>> >>>>> On Thu, Jan 22, 2015 at 6:14 PM, Michael Blume <blume...@gmail.com> >>>>> wrote: >>>>> >>>>>> (defprotocol my-protocol >>>>>> (foo [this])) >>>>>> >>>>>> (extend-protocol my-protocol >>>>>> clojure.lang.IPersistentMap >>>>>> (foo [this] "hello from map")) >>>>>> >>>>>> (criterium.core/quick-bench >>>>>> (satisfies? my-protocol {})) >>>>>> >>>>>> (criterium.core/quick-bench >>>>>> (foo {})) >>>>>> >>>>>> Simply calling foo on an empty map takes 7 ns, >>>>>> but checking whether the map satisfies my-protocol takes 22 µs, 3000 >>>>>> times longer. >>>>>> >>>>>> It seems like to call foo, some mechanism has to look up an >>>>>> implementation of my-protocol for maps -- how is it we can do that so >>>>>> quickly for a call and so slowly for satisfies? >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "Clojure" group. >>>>>> >>>>> To post to this group, send email to clo...@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+u...@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+u...@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 clo...@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+u...@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+u...@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 clo...@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+u...@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+u...@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. > -- You received this message because you are subscribed to the Google Groups "Clojure" group. 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