3 ms·

It's a narrow point, but the coincidence of "make the dynamic language fast enough that you don't need static types" and talk about equivalent perf using boxed

It's a narrow point, but the coincidence of "make the dynamic language fast enough that you don't need static types" and talk about equivalent perf using boxed math reminds me of the old saw about a sufficiently smart compiler[1]. Yeah, maybe the hotspot/jrockit wizards will be able to wave a wand and make everything fast. But, until the stars align in that department,[2] being able (and in Clojure's case, defaulting) to fast, static, primitive math is a good thing IMO, and really, really important to getting work done in certain domains today. In the meantime, I greatly appreciate your pushing. :-D [1] http://c2.com/cgi/wiki?SufficientlySmartCompiler http://c2.com/cgi/wiki?SufficientlySmartCompiler [2] e.g. http://blogs.oracle.com/jrose/entry/fixnums_in_the_vm http://blogs.oracle.com/jrose/entry/fixnums_in_the_vm

headius 15y ago
I certainly agree. As an implementer of Ruby, I've wanted type-hinting escape hatches to make my job easier. Given that they're likely never going to happen, I will continue to optimize the hard way and work closely with JVM guys :)
rbranson 15y ago
JRuby generates direct, "static" dispatches to the Fixnum class when you throw the --fast flag. However, this is not backwards compatible with MRI Ruby, so it's not default. Clojure does not attempt to maintain compatibility with anything, so there you go.
- headius 15y ago
  That's not true anymore. --fast is mostly eliminated now, with all features either on by default or replaced by better compilation. Math-like dispatches go through different dispatch logic optimized for Fixnums and Floats, this is true. If possible, they dispatch directly rather than dynamically. But they do this under global "isFixnumModified" and "isFloatModified" guards, to match Ruby behavior. The extra check did not significantly add to the overhead of math operations. Of course with invokedynamic, all dispatch is done the same way, and indy optimizes as well as our old tricks in both the unmodified and modified cases. Yay invokedynamic!
  - rbranson 15y ago
    Cool. Of course, the is-modified flags don't do much for large, idiomatic Ruby applications. As soon as anyone modifies Object, Class, or Fixnum (as seen in Rails), it goes right back to slow dispatch mode, which is why invokedynamic is so great.

headius 15y ago

I certainly agree. As an implementer of Ruby, I've wanted type-hinting escape hatches to make my job easier. Given that they're likely never going to happen, I will continue to optimize the hard way and work closely with JVM guys :)

rbranson 15y ago

JRuby generates direct, "static" dispatches to the Fixnum class when you throw the --fast flag. However, this is not backwards compatible with MRI Ruby, so it's not default. Clojure does not attempt to maintain compatibility with anything, so there you go.

headius 15y ago
That's not true anymore. --fast is mostly eliminated now, with all features either on by default or replaced by better compilation. Math-like dispatches go through different dispatch logic optimized for Fixnums and Floats, this is true. If possible, they dispatch directly rather than dynamically. But they do this under global "isFixnumModified" and "isFloatModified" guards, to match Ruby behavior. The extra check did not significantly add to the overhead of math operations. Of course with invokedynamic, all dispatch is done the same way, and indy optimizes as well as our old tricks in both the unmodified and modified cases. Yay invokedynamic!
- rbranson 15y ago
  Cool. Of course, the is-modified flags don't do much for large, idiomatic Ruby applications. As soon as anyone modifies Object, Class, or Fixnum (as seen in Rails), it goes right back to slow dispatch mode, which is why invokedynamic is so great.