Re: no names allowed, we serve types only

From: Nilone <reaanb_at_gmail.com>
Date: Sun, 14 Feb 2010 14:22:27 -0800 (PST)
Message-ID: <2972f5f3-0ee2-445e-83d9-dd634861e946_at_d27g2000yqn.googlegroups.com>



On Feb 13, 10:53 pm, Keith H Duggar <dug..._at_alum.mit.edu> wrote:
> I'm wondering, do we really need A? Can we not simplify this
> header notion to just a set of types? All we need do then is
> supply operators to conveniently "copy" types if or when one
> needs multiples attributes of the "same" type.

I'm happy to see some activity in here again.

Your suggestion could help to force developers to derive uniquely named types for their attributes - Name instead of String, Age instead of Int, and so on. Otherwise, type names aren't descriptive enough and will result in the annotation of schemata with comments, with all the associated problems. It'll happen anyway, of course - if something is optional, people will skip it.

I also see some problems with type checking. Consider the query "SELECT * FROM Point2D WHERE X = Y". Comparison of the attributes require that they be the same type (or at least, one should be a subtype of the other). Distinguishing unnamed attributes require that they be unique types, which is the reason for copying them, but that contradicts the comparison requirement. Received on Sun Feb 14 2010 - 16:22:27 CST

Original text of this message