Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!mailrus!ncar!noao!arizona!gudeman
From: gudeman@cs.arizona.edu (David Gudeman)
Newsgroups: comp.lang.misc
Subject: Re: He's not the only one at it again!
Message-ID: <24153@megaron.cs.arizona.edu>
Date: 11 Aug 90 22:10:51 GMT
Organization: U of Arizona CS Dept, Tucson
Lines: 32

In article  <27159@nigel.ee.udel.edu> carroll@udel.edu (Mark Carroll <MC>) writes:
=In article <675@garth.UUCP> smryan@garth.UUCP (sous-realiste) writes:
=]]_not_ a feature of our programs.  If I declare
=]]	var x: 12223495872309457 .. 2345230549872039458720983475;
=]]then any compiler worth its salt ought to be able to figure out how many
=]]of its nasty little boxes to use, and how to exploit whatever instructions
=].	.	.
=]
=]Do you have any idea what this does to the context sensitive grammar of
=]the language?
=
=This seems to be nothing more than Pascal like subranges combined with 
=Lisp-like bignums.

Lisp does not include the type system in the grammar.  All values in
Lisp have to carry their type around with them, and all operations
have to check the type at run time to make sure the operation is
legal.  This slows things down.  Pascal, C and similar languages fix
the types of variables and other expressions at compile time.

I don't agree with the original author that this is a problem though.
Given different lengths of integers, operations can be defined to
produce an int of length equal to the length of the longest operand.
Given subranges of the sort described, the result of an operation
should be an integer of the same length as the longest subrange, with
no range restrictions.  The range restrictions are checked when
assigning to a variable that has a restricted range.
-- 
					David Gudeman
Department of Computer Science
The University of Arizona        gudeman@cs.arizona.edu
Tucson, AZ 85721                 noao!arizona!gudeman