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From: susser@cit-vax.UUCP
Newsgroups: net.lang.st80
Subject: Typed Smalltalk
Message-ID: <799@cit-vax.Caltech.Edu>
Date: Sat, 12-Jul-86 20:04:02 EDT
Article-I.D.: cit-vax.799
Posted: Sat Jul 12 20:04:02 1986
Date-Received: Sat, 12-Jul-86 23:20:22 EDT
Organization: California Institute of Technology
Lines: 40

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?

I have always felt, deep in my heart, that strongly typed languages
were invented by compiler writers to make their job easier and my job
harder.  When I first encountered Smalltalk two years ago, I was
overjoyed to find a useful untyped language.  In the past two years,
I have realized that Smaltalk is indeed typed, but in a more subtle,
useful way than compiler writers would have us believe a language
should be typed.  In my mind, computers are supposed to do the grungy
work and let me do the creative work.  Declaring types is grungy work
that does nothing for me and should be handled by the computer in some
way.  Smalltalk does just that.  If I use the wrong class of object, I
quickly find out about it when a 'message not understood' window pops
up on my display.  It is then ridiculously easy to find what I have
done wrong and correct it.  I find dealing with types in pascal much
less satisfying.

I have also found that one of Smalltalk's stongest points is its
polymorphic nature.  Smalltalk's numeric system and collection classes
are two of the best examples of the power and flexibility that an
untyped polymorphic language can give you.  When I write a numeric
algorithm in Smalltalk, it is useful for all kinds of numbers -
SmallInteger, LargeInteger, Float, Fraction, Complex, Matrix, or any
other kind of number I care to write - and I just don't care what type
of number somebody may pass to my method.  In those few cases when I
do care, I can easily determine an object's species or class and make
an intelligent decision based on that information.

If there is something that type checking can bring to Smalltalk, I
just don't see it.  If there is someone out there who does see an
advantage to types in Smalltalk, I'd like to hear about it.  (Sounds
like a good topic for a net discussion to me.)

-- Josh Susser
   susser@csvax.caltech.edu
   susser.pasa@xerox.com

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