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From: gvcormack@watmum.UUCP
Newsgroups: net.lang.st80
Subject: Re: Typed Smalltalk
Message-ID: <546@watmum.UUCP>
Date: Sun, 13-Jul-86 13:50:47 EDT
Article-I.D.: watmum.546
Posted: Sun Jul 13 13:50:47 1986
Date-Received: Sun, 13-Jul-86 22:24:29 EDT
References: <799@cit-vax.Caltech.Edu>
Organization: U of Waterloo, Ontario
Lines: 27

> I have recently noticed few messages related to adding type mechanisms
> to Smalltalk.  I fail to see the appeal in adding types to Smalltalk.
> Is there any advantage to a strongly typed Smalltalk?

Does typing have any place in programming languages?  Yes it does.
Are existing statically typed languages inadequate?  Yes they are.
Is Smalltalk untyped?  No. It is dynamically typed.

There is no doubt that dynamic typing and dynamic procedure binding
like in Smalltalk offer the programmer a lot of flexibility.  However,
they also make it very difficult to make assertions about what the
program does.  I do not agree at all that "one quickly gets an
obvious error message" when one runs an incorrect Smalltalk program;
it may run for years before crashing, and when it does, the bug may
be anything but obvious.

So I am 100% behind any attempt to introduce static type checking
(which would guarantee that the error "don't understand xxx" would
never occur), provided that it does not destroy the polymorphic
capabilities of the language.  Everyone interested in this topic
should read  "Implementing Russel" by Boehm and Donahue in Proc.
Sigplan 86 (June Sigplan Not.).
-- 
Gordon V. Cormack      CS Department, University of Waterloo
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