[racket-dev] Manual inlining destroys performance for this program

From: Sam Tobin-Hochstadt (samth at cs.indiana.edu)
Date: Thu Aug 22 10:59:35 EDT 2013

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)])

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?


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