Re: Principle of Orthogonal Design

On Feb 9, 9:26 am, Marshall <marshall.spi..._at_gmail.com> wrote:

> However
> quantifiers in logic come with their own lexical scope. (They
> must, since they introduce local names.)

This is a good point, and there are constructs such as for integration, product, summation and limit that also introduce local names that are invisible to the containing context, and are said to be "bound", not "free".

I think an explicit syntax for introducing a lexical scope for a variable that is explicitly bound to some expression works nicely.

Eg (let a=x in f(a)) is equivalent to f(x)

and the query

    P(a=y, b=x) & Q(a=x, b=z))

where P,Q are relations with attributes named a,b would instead be written as

    (let a=y,b=x in P) & (let a=x, b=z in Q) Received on Fri Feb 08 2008 - 20:41:19 CST