Hi, Carl
Carl Read wrote:
>
> > ...
>
> Indeed. But it suggests a way I haven't seen posted...
>
> >> colors: [red green blue]
> == [red green blue]
> >> forever [print color: colors/1 remove append colors color]
> red
> green
> blue
> red
> green
> blue
> red
> green
> blue
> red
> green
> blue
> red
> green
> blue
> red
> (escape)
>
> Has the advantage of no extra words being needed. The
> disadvantages being the contents of the colors block is
> cycling, (might or might not matter), and it may be slower...
> It should have a consistant speed though. Comments Joel?
>
Don't try this at home kids! ;-)
Cycling the values within the block does matter; there's much
more memory management overhead. Using the same benchmarks as
in the earlier comparison, the block-cycling version takes 4
to 5 times as long as the modulus approach for 3-10 elements.
In addition the
overhead grows with the length of the block being cycled:
bruteforce: func [n [integer!] c [integer!] /local t b v] [
b: make block! n
repeat i n [insert tail b i]
t: now/time/precise
loop c [ remove append b v: b/1 ]
t: to-decimal now/time/precise - t
]
behaves as:
>> for i 10 200 10 [print [i bruteforce i 500000]]
10 24.99
20 22.91
30 29.49
40 25.27
50 23.45
60 27.19
70 25.76
80 29.22
90 25.98
100 29.6
110 26.75
120 30.05
130 27.24
140 28.89
150 29.83
160 30.71
170 30.97
180 31.2
190 33.18
200 32.9
The raggedness likely indicates intermittent gc operations; the
trend is definitely upward as the block length grows.
-jn-
--
; Joel Neely joeldotneelyatfedexdotcom
REBOL [] do [ do func [s] [ foreach [a b] s [prin b] ] sort/skip
do function [s] [t] [ t: "" foreach [a b] s [repend t [b a]] t ] {
| e s m!zauafBpcvekexEohthjJakwLrngohOqrlryRnsctdtiub} 2 ]
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