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Date: Thu, 23 Jan 1997 09:45:50 +0100
From: Robb Nebbe <nebbe@iam.unibe.ch>
Organization: Dept. of CS, University of Berne, Switzerland
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Subject: Re: OO, C++, and something much better!
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Eric Clayberg wrote:

> 
> ... The more "rules" a language has, the more
> involved its syntax, and the more draconian its type system, then the
> more type errors are likely to be created by the developer and then
> caught by the compiler.

This shows a fundamental misunderstanding about what a type system is
and what it does. Typing is a property of how you set up your model, not
of which language you use to code it.

A type system does have some influence on how a model can be expressed
but a good object-oriented type system places few constraints on how you
set up the model. Currently there are some advantages to some kind of
dynamic scheme but I would expect these advantages to disappear as
static type systems improve.

> In a language like Smalltalk which has an
> absurdly simple, consistent syntax, and which has a very open-mined
> concept of "type", very few type errors are ever created to begin with
> and thus very few actually exist to be found. The *few* real type errors
> that are created tend to be caught almost immediately by Smalltalk's
> superb debugging facilities.

Speaking of hubris ... you can argue that people tend to code
differently
in Smalltalk thus avoiding the possibility of type errors is a few cases
but just asserting that their is something magical about Smalltalk is
silly.
Obviously the lack of static typing in Smalltalk does not make it
unsuitable
for software development, a fact that some people (probably those who
have
never programmed in Smalltalk) seem to have trouble grasping.

However, dynamic typing is mostly a stop-gap measure since static type
systems aren't quite up to snuff yet. I expect static type systems to
steadily improve until there is no longer any reasonable justification
for
dynamic typing but we aren't there yet in my opinion.

Robb Nebbe
