[REBOL] TECHNICAL ESSAY/CHALLENGE(s) - "Expression Based"? Re:(2)
From: al:bri:xtra at: 3-Oct-2000 0:22
This is a bit shorter, but still not as nice as the Rebol way as used in
System and View.
[
Rebol [
File: %Tally.r
]
tally: make object! [
tot: 0
zero: does [tot: 0]
up: func [/by n [number!]] [print "up!" tot: tot + either by [n] [1]]
down: func [/by n [number!]] [print "down!" tot: tot - either by [n]
[1]]
now?: does [tot]
]
bunchanums: [3 1 35 8 4 5 52 42 19 13 32 43 81 2 6 34 46]
; A better name for this function would be appreciated.
mpc: func [Block [block!]] [
make path! compose Block
]
; A better name for this function would be appreciated.
dr: func [Block [block!]] [
do reduce Block
]
use [diffs] [
diffs: make tally []
evens: make tally []
odds: make tally []
foreach num bunchanums [
dr [mpc [diffs (either even? num ['up] ['down]) by] num]
dr [mpc [(either even? num ['evens] ['odds]) up by] num]
]
print ["diffs/now?" diffs/now?]
print ["evens/now?" evens/now?]
print ["odds/now?" odds/now?]
]
]
>> do %Tally.r
down!
up!
down!
up!
down!
up!
up!
up!
up!
up!
down!
up!
up!
up!
up!
up!
down!
up!
down!
up!
up!
up!
down!
up!
down!
up!
up!
up!
up!
up!
up!
up!
up!
up!
diffs/now? 26
evens/now? 226
odds/now? 200
AllenK has a better grasp of the ideal Rebol way to do this. But he says it
is difficult to explain. More about this later, or you could pester Allen.
:-)
Andrew Martin
While chatting to fellow Rebolians...
ICQ: 26227169
http://members.nbci.com/AndrewMartin/
http://members.xoom.com/AndrewMartin/
