It looks like you may want `define-inline' from `racket/performance-hint'. Vincent
At Thu, 22 Aug 2013 11:11:51 -0400, Sam Tobin-Hochstadt wrote: > > Ah, indeed. I'm calling `random` in the closure now. Fixing that > removes the anomaly. > > Sam > > On Thu, Aug 22, 2013 at 11:05 AM, Matthew Flatt <mfl...@cs.utah.edu> wrote: > > At Thu, 22 Aug 2013 10:59:35 -0400, Sam Tobin-Hochstadt wrote: > >> This short program generates a lot of closures, and thus doesn't run very > >> fast. > >> > >> #lang racket/base > >> > >> (require racket/flonum) > >> > >> (define (Point x0 x1 y0 y1) > >> (list (λ () (let ([x (- x1 x0)] [y (- y1 y0)]) > >> (flsqrt (+ (* x x) (* y y))))))) > >> > >> (define iter 1e4) > >> (for ([i (in-range iter)]) > >> (define p (Point (random) (random) (random) (random))) > >> (define f (car p)) > >> (for ([i (in-range 1e3)]) > >> (f))) > >> > >> I tried manually inlining `Point` by replacing `define` with > >> `define-syntax-rule`, and the program gets about 8x *slower*. I don't > >> have any idea why this is happening, especially since `Point` is > >> actually inlined by the optimizer in the `define` case. > >> > >> Any idea why this might be? > > > > Using `define-syntax-rule' changes the program from > > > > (let ([x (random)]) > > (call-a-lot (lambda () x))) > > > > to > > > > (call-a-lot (lambda () (random))) > > > > > > Did you mean to try > > > > (define (Point x0 x1 y0 y1) > > (let ([x (- x1 x0)] [y (- y1 y0)]) > > (let ([v (flsqrt (+ (* x x) (* y y)))]) > > (list (λ () v))))) > > > > ? > > > > _________________________ > Racket Developers list: > http://lists.racket-lang.org/dev _________________________ Racket Developers list: http://lists.racket-lang.org/dev
