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(ice-9 time)

From: Marius Vollmer
Subject: (ice-9 time)
Date: 21 Mar 2001 01:21:28 +0100
User-agent: Gnus/5.0803 (Gnus v5.8.3) Emacs/20.7


why did you write `time' as a macro?  It does not actually expand into
code, but performs the action itself.  This will make it fail with a
compiler.  (It doesn't matter in the repl, but `time' can easily be of
broader use.)

Also, it does use `eval' which I find counter-intuitive.  (Because of
`eval', you can't really time code in a lexical environment.)

I would have written it like this:

    (define (time-proc proc)
      (let* ((gc-start (gc-run-time))
             (tms-start (times))
             (result (proc))
             (tms-end (times))
             (gc-end (gc-run-time)))
        (define (get proc start end)
          (/ (- (proc end) (proc start)) internal-time-units-per-second))
        (display "clock utime stime cutime cstime gctime\n")
        (format #t "~5,2F ~5,2F ~5,2F ~6,2F ~6,2F ~6,2F\n"
                (get tms:clock tms-start tms-end)
                (get tms:utime tms-start tms-end)
                (get tms:stime tms-start tms-end)
                (get tms:cutime tms-start tms-end)
                (get tms:cstime tms-start tms-end)
                (get id gc-start gc-end))

    (define-macro (time exp)
      (time-proc (lambda () ,@exp)))

What do you think?

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