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From: nick@lfcs.ed.ac.uk (Nick Rothwell)
Newsgroups: comp.lang.misc,comp.software-eng
Subject: Re: An Interesting View of "Strong" Vs. "Weak" Typing
Keywords: typing, Ada, Lisp, definitions, evidence
Message-ID: <1633@castle.ed.ac.uk>
Date: 16 Jan 90 12:02:38 GMT
References: <1990Jan13.155115.4809@mentor.com> <12843@cbnewsc.ATT.COM>
Reply-To: nick@lfcs.ed.ac.uk (Nick Rothwell)
Followup-To: comp.lang.misc
Organization: LFCS Enya Admiration Society
Lines: 27
In-reply-to: lgm@cbnewsc.ATT.COM (lawrence.g.mayka)

In article <12843@cbnewsc.ATT.COM>, lgm@cbnewsc (lawrence.g.mayka) writes:
>For this reason I submit that run-time typing is particularly
>appropriate for large software systems that must evolve
>continuously over a long lifecycle in response to unforeseen
>customer needs - e.g., feature-rich telecommunications switching
>systems.

I see no reason why you can't do that kind of thing with a static
type system, as long as it's flexible enough. If you have
polymorphism, type abstraction, parameterised types and a decent
type-secure module system then the abstraction mechanisms limit
the amount of dependency between modules, so that changes are
as localised as possible. Even for the inevitable global changes,
if you trust the type system, then you can tend to make the changes to
the support modules which provide the basic types, and let any
changes to the types and sharing constraints propagate through.
The work is done when the typechecker accepts the whole system
once again.

>	Lawrence G. Mayka

	Nick.
--
Nick Rothwell,	Laboratory for Foundations of Computer Science, Edinburgh.
		nick@lfcs.ed.ac.uk    <Atlantic Ocean>!mcvax!ukc!lfcs!nick
~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~
  "...all these moments... will be lost in time... like tears in rain."