[REBOL] Re: percent! - new datatype request
From: chalz:earthlink at: 7-Jun-2002 1:12
I'm coming in to this discussion a little late, but here's the way I,
personally, would see it.
> 100 - 50% == 50 ; as first stated
This, to me, would equate to:
100 - (100 * .50) == 50
Similarly:
200 - 50% == 200 - (200 * .5) == 100
> I suppose
> 50% - 100 == -50% ; ? or should be illegal?
I don't think you could really do that, because just what is that 50% *of*?
Perhaps 50% - 100% ..
> And
> 50% * 100 == 5000%
> 100 * 50% == 50
An interesting thought. Should
100 + 50% == 100 + (100 * .5)
and
100 * 50% == 100 * .5
? 50% * 100, though.. I can see where that would be believable. :/
> > Shouldn't that be
> >
> > >> 100 - 50%
> > == 50%
Not necessarily. It'd be 100 minus 50% of 100, which is 50. Otherwise, you
should stick with 100% - 50% = 50%..
> > and thus
> >
> > >> rate: 8.25%
> > == 8.25%
> > >> price: $100.00
> > == $100.00
> > >> tax: price * rate
> > == $8.25
Precisely; the datatype of the first value, the value upon which the percent
is being acted, should be the returned datatype. No?
> > >> taxrate: to-percent [$8.25 / $100]
> > == 8.25%
to-percent on type block! ? I don't see why. Use parens, perhaps, if you
feel the need, but
traxrate: to-percent $8.25 / $100
should be fine. Results in (8.25E-2 * 100), more or less.
Some related, interesting behavior. You can do money! + money!, money! -
money!, money! / money!, but not money! * money!. Heh. money! / money!
results in number!. (I like how integer! and decimal! values all fall under
the category number! .. workes nicely.)
--Charles
