Matthias Felleisen writes: > You can count on Racket to inline a bunch of such small functions. > You can use Optimization Coach to check on your understanding of > what the compiler actually does, and you may benefit from its advice.
Optimization Coach sounds interesting, I'll install it next time I am in the free world (raco doesn't work through my lab's http proxy, unfortunately). For now I tried decompile to see what happens. I confirm that my vadd function gets inlined, and also that there is no further useful optimization in plain Racket. When I move to Typed Racket, field accesses in structures and element accesses in vectors are done by "unsafe-..." operations which are presumably faster because they don't do type and value checks. I suspect there is no difference in unsafe access performance between a struct and a vector, since it's the same operation once the checks are eliminated. At the bytecode level, it doesn't make a difference which number type I use for the elements of my struct or vector. Even Fixnum with operations from unsafe/ops leads to the same code. There's probably a difference for the JIT, but that's an exploration for another day. > Currently, Racket does not perform loop fusion or deforestation > for data structures that merely connect loops/functions/etc. What I like about this statement is the word "currently" :-) > In general, it is a mistaken assumption however that even in a > 'managed' language -- such as Java or Racket -- mutation is still > faster than de/allocation of short-lived data structures. If you I didn't make that assumption. In fact, I didn't even consider any approach based on mutation. If I wanted to write Fortran code, I'd use Fortran. > I would definitely recommend (1) using Typed Racket and (2) using > the most efficient numbers that we offer in TR. I'd also keep the > entire program in TR. I'd still write code in the most mathematical > manner and consult OC to see how to squeeze the most out of this style. > When I found that certain styles don't get optimized the way I expect > them to get optimized, I would ask the Racket devs whether they could > make improvements so that specific functions/programs work better. Thanks for those recommendations, I'll see how far I get. After today's explorations, I conclude that there's probably no difference between structs and vectors once I am in the Typed Racket universe, so I'll stick to structs for now. Sam Tobin-Hochstadt writes: > I encourage you to find some evidence showing that Konrad's assumption > is mistaken, then. It's not mine - but please go ahead figuring out what's best anyway! Konrad. ____________________ Racket Users list: http://lists.racket-lang.org/users
