On Fri, 2008-03-21 at 12:42 -0700, Brendan Eich wrote: > Again, I'm not writing checks I can't yet cash (but we are investing, > making bets in code under development). On the other hand, IMHO you > are pessimizing for the two-decade-old trailing edge. It's easy to go > from "want speed" to "require static types" and bypass the "optimize > dynamic types enough not to need more speed" state, but taking this > shortcut risks leaving lots of developers and content behind. It's a > huge rewrite tax at the limit, unpayable on the web.
I may be wrong but I have the feeling that the works you quote use type-feedback and that type-feedback only optimizes [single] method dispatch. ES4 has multi-methods, which are harder to optimize, plus there are plenty of other checks that may be optimized away which are related to typing but not to method dispatch, say pattern-matching, "wrap", etc. In addition, iirc, type-feedback only works after the first execution of code, so it is not necessarily useful when objects are re-created at each execution of the body of a loop, etc. Now, of course, I might be wrong. I'm not really a specialist in OOP implementation. > What's more, if the static type system is weak, this course may just > amount to requiring programmers to overspecify their code for the > sake of VM implementors, without gaining much in the way of safety > properties or other programming in the large benefits. Such > overspecification can turn code into "hardware" that is hard to > evolve quickly, mash up, merge and diverge, reuse at Web scale, etc. I concur with that. In order to maintain readability, most optimizations should happen behind-the-scene i.e. by using either type inference (or something more complicated but of the same kind) or type-feedback. Cheers, David -- David Teller Security of Distributed Systems http://www.univ-orleans.fr/lifo/Members/David.Teller Angry researcher: French Universities need reforms, but the LRU act brings liquidations. _______________________________________________ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
