Perfect explination, thanks! kl. 20:41:56 UTC+2 onsdag 6. august 2014 skrev Reid McKenzie følgende: > > Functions are objects implementing the IFn interface. This interface > defines a set of methods named "invoke" which return an object given up to > 21 arguments. Once the compiler is done emitting any given function, an > IFn object has been created. Def is a general operation which creates a > value and binds it to a var named by the current (*ns*, symbol) pair. So > for defn and an instance of this IFn object is what the bound var points > to. So as an example, > > user=> (defn foo [x y] (+ x y 1)) > ; macroexpanded (def foo (fn* ([x y] (+ x y 1)))) > #'user/foo > > If you inspect the user namespace, you will find that the symbol foo now > maps to the var #'user/foo. Subsequent textual occurrences of the symbol > foo in this namespace will at compile time be mapped to the var #'user/foo, > and the emitted code will take the var #'user/foo and dereference it to get > an IFn object implementing the foo function which can be invoked. > > As there is overhead associated with dereferencing a var and some code > such as clojure.core/* is expected not to be redefined by users, the > ^:static annotation in Clojure 1.3 directed the compiler to emit `public > static invokeStatic` methods in addition to the normal `public invoke` > methods. This allowed potentially hot path functions to statically invoke > each other rather than using var indirection. This static linking of > function calls is how Oxcart achieves the reported 24% speedup, and the > linked direct branch is Rich implementing invokeStatic again, presumably > for Clojure 1.7. > > This static linking feature was introduced in Clojure 1.3 and removed in > Clojure 1.4 because as I mentioned in my linked blog post the downside of > static linking is that live development and code redefinition become harder > or impossible. My expectation is that, as 1.7 is projected to introduce > compilation profiles, this problem will be mitigated by different builds or > profiles of Clojure which may enable or disable static linking in a user > visible manner. So for an application deployment build you may choose > [org.clojure/clojure "1.7.0-static"] which can use ^:static annotations for > a speedup while for development you may use [org.clojure/clojure "1.7.0"] > which may ignore ^:static in exchange for a better REPL experience as > Clojure 1.6 and 1.5 do. > > Hope this helps, > Reid > > On 08/06/2014 11:22 AM, Robin Heggelund Hansen wrote: > > Don't understand the compiler that well. Could you provide a short > description of what is being done? > > kl. 13:05:40 UTC+2 onsdag 6. august 2014 skrev Jozef Wagner følgende: >> >> See this WIP branch https://github.com/clojure/clojure/tree/direct >> >> On Wednesday, August 6, 2014 12:54:32 PM UTC+2, Robin Heggelund Hansen >> wrote: >>> >>> Just read this blog post about Oxen ( >>> http://arrdem.com/2014/08/05/of_oxen,_carts_and_ordering/?utm_source=dlvr.it&utm_medium=twitter). >>> >>> In it is mentioned that Rich is re-introducing invokeStatic to achieve a >>> possible 10% performance increase for Clojure 1.7. >>> >>> I couldn't find any information about this. Anyone know where I can find >>> out more? >>> >> -- > 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 <javascript:> > 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 <javascript:> > 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 <javascript:>. > For more options, visit https://groups.google.com/d/optout. > > >
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