Is 'everything' a refrence or isn't it?
fakeaddress at nowhere.org
Sun Jan 15 12:48:41 EST 2006
Mike Meyer wrote:
> Actually, what "data type" implies to me is that data have a type. But
> skip that for now - what's the data that goes along with an instance
> of object?
Again, I'm not an expert on 'object'. When a type has
a single value instances can take, the value is simply
defined as the single instance of the type.
>>The fact that general principles and results depend on each
>>object having a value implies they must.
> *What* general principles? *What* results?
Those that refer to the value of an instance without
covering the special-case of valueless objects. You've
seen some, and could not cite anything that includes
the case of valueless instances.
Mathematical methods break. In reasoning about the
correctness of implementations, we define functions
(mathematically, not in code) that map representations
to the values they represent. To allow some instances
to be valueless, we'd then need mathematical variables
that range over non-values.
> That my repeated requests for a definition of "type"
> (or "object) have never been answered
See the first sentence of the Wikipedia article on data
> So you're claiming that "all objects have values" is a convenience,
> like "x raised to the power 0 is 1"?
All definitions are a convenience. Not special-casing
addition to define 2+2 to be five is a convenience that
makes our results cleaner.
> Ain't got none. On the other hand, I'm not trying to prove that such
> objects exist. I'm trying to find out if there's any justification for
> claiming that they don't exist.
It's the reference, it gets to decide.
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