yes it is:
(define thunk1 (lambda () (/ 100 10)))
(define thunk2 (lambda () (eval '(/ 100 10))))
(define iterate (lambda (ct thunk)
(if (zero? ct)
#t (begin (thunk) (iterate (- ct 1) thunk)))))
(time (iterate 1000000 thunk1))
=> cpu time: 15 real time: 16 gc time: 0
(time (iterate 1000000 thunk2))
=> cpu time: 21110 real time: 21125 gc time: 436
----- Original Message -----
From: Joe Gilray
To: Racket mailing list
Sent: Thursday, July 19, 2012 7:15 AM
Subject: [racket] Is eval very slow?
Hi,
I've written some code that uses eval:
(define ops (list * / + -))
(define digits '(1 2 3 4 5))
(for ([dl (combinations 4 digits)])
(define lst '())
(for ([d (permute-all dl)])
(for* ([o1 ops] [o2 ops] [o3 ops])
(unless (and (eq? o1 /) (zero? (eval (list o2 (second d) (list o3
(third d) (fourth d)))))) ; avoid divide by zero
(define val (eval (list o1 (first d) (list o2 (second d) (list o3
(third d) (fourth d))))))
(when (>= val 1) (set! lst (cons val lst)))) ...
It runs very, very slowly. Am I doing something wrong? Is there a way to
speed up eval?
Thanks,
-Joe
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