Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!att!cbnewsc!lgm
From: lgm@cbnewsc.ATT.COM (lawrence.g.mayka)
Newsgroups: comp.lang.misc
Subject: Re: An Interesting View of "Strong" Vs. "Weak" Typing
Message-ID: <12680@cbnewsc.ATT.COM>
Date: 9 Jan 90 16:20:03 GMT
References: <16678@megaron.cs.arizona.edu>
Reply-To: lgm@cbnewsc.ATT.COM (lawrence.g.mayka,ihp,)
Organization: AT&T Bell Laboratories
Lines: 34

In article <16678@megaron.cs.arizona.edu> gudeman@cs.arizona.edu (David Gudeman) writes:
>I think a better method to make this sort of distinction is to use the
>traditional definition of "typed" vs. "untyped" languages that I

The difficulty with these definitions is that they so easily
mislead people.  "Conventional wisdom" has decided - based on
comparisons between strong and weak compile-time typing - that
Types are Good and therefore, Strong Types are Better.  This
"conventional wisdom" is then often applied disparagingly to
run-time typing.  Run-time typing encourages a programming style
radically different from that of "weak" compile-time typing and
should not be placed in the same category.

>systems.  Define "tagged type systems" as systems where the
>representation of the data uniquely identifies both the type of the
>data and its value.  Define "untagged type systems" as those systems
>where representations are overloaded (i.e.: a single representation
>stands for a different value in several different types), and the type
>must be known before it is possible to determine exactly what value is
>being represented.

Any of these seem reasonable and roughly equivalent distinctions:

compile-time typing vs run-time typing
static typing vs. dynamic typing
untagged typing vs. tagged typing
identifier typing vs. object typing
textual typing vs. behavioral typing

	Lawrence G. Mayka
	AT&T Bell Laboratories
	lgm@ihlpf.att.com

Standard disclaimer.