Re: Static or runtime type-checking (was: Program compression)


"Robert Maas, http://tinyurl.com/uh3t"; <seeWebInstead@xxxxxxxxxxxxxxxx> wrote in message news:rem-2008sep17-001@xxxxxxxxxxxx

But never mind. Part of intentional type is range checking, and you
already admitted that compiletime static type checking can't deal
with that correctly. For example, if I have GPS coordinates with
latitude and longitude and altitude, then latitude must be from -90
degrees to +90 degrees, inclusive at both ends, longitude must be
from -180 degrees to +180 degrees, exclusive at one end or other,
and where if latitude is at pole then longitude doesn't matter, and
altitude must be from -10 miles (deepest drillhole where a GPS
receiver might work) to +100 or so miles (highest altitude where
downward-directed antennas on GPS satellites can send the signal).
So how are you going to do trigonometry on such values, converting
from one GPS location to another, without runtime type checking to
make sure the final result is valid?

What does all this application-specific stuff have to do with the design of a programming language?

Are you suggesting you should be able to specify a range-check to this level of detail?

(And even if you could, you could still have a gps point wrongly located anywhere in the world.)

--
Bartc

.

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