It just doesn't accurately describe how primitive fns work when used
non-higher order, nor is it correct for the tricks you can play with
non-higher order fn usage + :inline metadata. JVM will aggressively inline
these cases.


On Thu, Apr 25, 2013 at 1:03 PM, Alice <dofflt...@gmail.com> wrote:

> Care to elaborate which part is out of date?
>
> On Apr 26, 1:48 am, David Nolen <dnolen.li...@gmail.com> wrote:
> > Which is out of date.
> >
> >
> >
> >
> >
> >
> >
> > On Thu, Apr 25, 2013 at 12:47 PM, Alice <dofflt...@gmail.com> wrote:
> > > Found this blog post written by fogus:
> >
> > > "To provide this level of flexibility Clojure establishes a level of
> > > indirection. Specifically, all function lookups through a Var occur,
> > > at the lowest level, through an atomic volatile. This happens every
> > > time that a function bound using the def/defn special forms is called.
> > > This indirection is not amenable to HotSpot optimizations."
> >
> > >http://blog.fogus.me/2011/10/14/why-clojure-doesnt-need-invokedynamic.
> ..
> >
> > > On Apr 25, 10:19 pm, Alice <dofflt...@gmail.com> wrote:
> > > > I create many small methods in java without worrying about the
> > > > performance since it's usually the target of inline optimization. For
> > > > example,
> >
> > > > public class Foo {
> > > >   public static long inc(long l) {
> > > >     return ++l;
> > > >   }
> >
> > > >   public static long f1() {
> > > >     long l = 0;
> > > >     for (int i=0; i < 1000000000; i++) {
> > > >       l++;
> > > >     }
> > > >     return l;
> > > >   }
> >
> > > >   public static long f2() {
> > > >     long l = 0;
> > > >     for (int i=0; i < 1000000000; i++) {
> > > >       l = inc(l);
> > > >     }
> > > >     return l;
> > > >   }
> >
> > > > }
> >
> > > > (time (Foo/f1))
> > > > (time (Foo/f1))
> > > > (time (Foo/f1))
> > > > (time (Foo/f2))
> > > > (time (Foo/f2))
> > > > (time (Foo/f2))
> >
> > > > "Elapsed time: 23.309532 msecs"
> > > > "Elapsed time: 23.333039 msecs"
> > > > "Elapsed time: 21.714753 msecs"
> > > > "Elapsed time: 22.943366 msecs"
> > > > "Elapsed time: 21.612783 msecs"
> > > > "Elapsed time: 21.71376 msecs"
> >
> > > > But clojure funtions seem to be never get inlined.
> >
> > > > (def obj (Object.))
> >
> > > > (defn getObj [] obj)
> >
> > > > (defn f1 [] obj)
> > > > (defn f2 [] (getObj))
> >
> > > > (time (dotimes [n 100000000] (f1)))
> > > > (time (dotimes [n 100000000] (f1)))
> > > > (time (dotimes [n 100000000] (f1)))
> > > > (time (dotimes [n 100000000] (f2)))
> > > > (time (dotimes [n 100000000] (f2)))
> > > > (time (dotimes [n 100000000] (f2)))
> >
> > > > "Elapsed time: 67.758744 msecs"
> > > > "Elapsed time: 68.555306 msecs"
> > > > "Elapsed time: 68.725147 msecs"
> > > > "Elapsed time: 104.810459 msecs"
> > > > "Elapsed time: 103.273618 msecs"
> > > > "Elapsed time: 103.374595 msecs"
> >
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