No subject

saying the class 
is identical to the query. e.g. for the U.S.:

northern_city == city[latitude > 40]

Read as "A northern city is defined as a city with latitude greater than
forty", i.e. a latitude greater than forty is *sufficient* for concluding a
city is a northern city"

The more conventional mode of writing is:

northern_city : city;
northern_city.latitude > 40;

Read as "A northern city is a city. The latitude of a northern city is greater
than forty", i.e. a latitude greater than forty is *necessary* to be a
northern city (but there may be other requirements to be a northern city as
well)*.

So in short, the whole matter boils down to whether matching a collection of
attributes is *necessary* or *sufficient* for determing membership in a given
class by an arbitrary entity.  I do not see any reason why we cannot support
both methods.

- Mark



*Note that I use "==" to mean "is identical to" and ":" to mean "is a subset
of", e.g. "X == integer" and "x : integer" mean "X is a synonym for integer"
and "X is an integer", respectively. - These are critically different meanings
that we both use the word "is" to describe.

-- 
Mark Butler	       ( butlerm at middle.net )
Software Engineer  
Epic Systems              
(801)-451-4583