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000115_icon-group-sender _Mon May 6 22:17:27 1996.msg
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Received: by cheltenham.cs.arizona.edu; Tue, 7 May 1996 06:31:44 MST
Message-Id: <318E6C67.294D@tees.ac.uk>
Date: Mon, 06 May 1996 22:17:27 +0100
From: Hamish Lawson <H.Lawson@tees.ac.uk>
Organization: University of Teesside, School of Computing and Maths
X-Mailer: Mozilla 2.01Gold (Win95; I)
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To: Icon group <icon-group@cs.arizona.edu>
Subject: Why are 'every', 'until', and 'while' designed to fail?
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Status: O
Is there some reason why the 'every', 'until', and 'while' contructs
were designed so that they inevitably fail? There seems to me to be a
certain redundancy in having the control expression's termination or
failure signalled in this way, since we only get a value for the loop
when the loop has terminated anyway.
Would it not be more useful to have these contructs do something like
return the value of their 'do' expressions, thus allowing some
expressions to be expressed more elegantly and with less 'housekeeping'.
I don't envisage that such a change would break existing code, since
no-one presumably makes use as yet of the value of 'every', 'until', or
'while' expressions.
| Hamish Lawson, School of Computing and Mathematics,
| University of Teesside, Middlesbrough, Cleveland, UK, TS1 3BA
| Tel: +44 1642 212695 Fax: +44 1642 342604
| E-mail: H.Lawson@tees.ac.uk