At 11:16 PM -0600 8/16/06, David Green wrote:
On 8/15/06, Darren Duncan wrote:
At 2:51 PM -0600 8/15/06, David Green wrote:
[...]
You are right, but we have both Seq and Array types, so depending
which one you use, you want either the === or eqv operators to do
what you want. There is no reason that === should say 2 Array are
equal; we have eqv for that, or use 2 Seq instead of 2 Array if you
want === to return true on the same values.
Is Seq vs Array the right distinction here? A Seq is immutable, so
I can't change its size, for instance, which is not what I want. I
just want [1,2] to be === to [1,2], or [1,2, [EMAIL PROTECTED] to be equal to
[1,2, [EMAIL PROTECTED] but !=== [1,2, [EMAIL PROTECTED] -- eqv won't work in the latter case
(regardless of Seq vs. Array -- I didn't think it made a difference
here).
As a lead-in, I should say that Synopsis 3 has a good and complete
explanation of these matters and has had it for several weeks, in my
opinion.
Since you are wanting to compare two mutable Array, just use the eqv
operator, which will do everything you want in a terse and easy to
understand manner.
Generally speaking, the direct use of === is more for specialized
purposes, somewhat like the direct use of =:= is. If one can't tell
the difference between === and eqv, they most likely want snapshot
semantics anyway, and so might as well forget === exists, and just
use eqv everywhere.
There's no point arguing that === should deeply compare mutable types
when you already have eqv to do that. Continuing on like you appear
to be is like saying that the + operator should be useable to
concatenate two Str, when we have the ~ operator for that. Arguing
that === should deeply compare mutable types is like arguing that +
should contactenate two Str.
-- Darren Duncan
