[REBOL] Re: On mutability and sameness
From: joel:neely:fedex at: 13-Jun-2001 0:48
Hi, Holger,
Just to clarify, since I apparently wasn't clear initially...
Holger Kruse wrote:
> ... by definition, the date component of a date! value is
> another date! value, so /date returns what it is supposed
> to.
>
I understand what it does, and wasn't suggesting that it was
in error. Just that it looked funny.
> REBOL does not use different datatypes for "date without
> time" and "date with time". They are both of type date!.
>
But isn't this the only case in which a "component" of a
complex (non-atomic) data type is of the same type as its
container
with unbounded descent? In all other cases,
extracting a component gets something that is (in some well-
defined sense) simpler than the whole with which one started.
(Of course, I'm speaking of built-in types... One can always
build pathological self-referential structures such as
>> pathology: [1 2] == [1 2]
>> insert/only next pathology pathology == [2]
>> pathology/1 == 1
>> pathology/2/1 == 1
>> pathology/2/2/1 == 1
>> pathology/2/2/2/1 == 1
>> pathology == [1 [...] 2]
Kudos to whomever implemented the infinite-recursion-bailout
evidenced by the last line above!)
-jn-
------------------------------------------------------------
Programming languages: compact, powerful, simple ...
Pick any two!
joel'dot'neely'at'fedex'dot'com
