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From: shang@corp.mot.com (David L. Shang)
Subject: Re: Types, types: static vs. dynamic -- classification
Reply-To: shang@corp.mot.com
Organization: MOTOROLA 
Date: Mon, 20 Nov 1995 15:08:46 GMT
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In article <30AB828E.5C7F@cs.brown.edu> Seth Tager <sdt@cs.brown.edu> writes:
> David L. Shang wrote:
> 
> > The definition of type itself has nothing to do with a compiler! What
> > you stated here is the usage of a type by a compiler. We should
> > define a thing by saying what it is, not by saying how it is used.
> > The different usage may have imapct on a definition, but it
> > only contributes to the detailed distinction, not the thing in its
> > nature.
> 
> I dont agree. If I use a stick to draw in the dirt, it's a writing 
> implement. If I throw it on a fire, it's fuel. The task that it's 
> used for is the interesting modifier, not the thing itself.
> 

Whether you use a stick to draw or throw it on a fire, the set of
functions of a stick is invariant. Whether a stick is used as a drawing
device or as fuel, it should not affect its definition: 

	* a woody piece or part of a tree or shrub
	* a long slender piece of wood
	* any of various implements resembling a stick in shape,
	  origin, or use

But you can not define a stick by its fantasy usage like being a pen or
fuel. I can virtualy use any solid thing that I can hold to draw,
but is any solid thing a stick?

Look up any dictionary, I bet there is no mention of pen or fuel
under the definition of a "stick" (except for examples). 

If there is something with an unique usage, you might use it in
definition.  But the usage only is still insufficient to define
a thing.

David Shang
