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From: JWC@IDA.LiU.SE (Jonas Wallgren)
Newsgroups: comp.lang.functional
Subject: Re: What is strong typing? (Was: I like strong typing)
Message-ID: <1990Aug10.014104.6268@ida.liu.se>
Date: 10 Aug 90 01:41:04 GMT
Sender: jonwa@ida.liu.se (Jonas Wallgren)
Organization: CIS Dept, Univ of Linkoping, Sweden
Lines: 27

In article <5448@castle.ed.ac.uk> nick@lfcs.ed.ac.uk (Nick Rothwell) writes:
>In article <3263@stl.stc.co.uk>, tom@stl.stc.co.uk (Tom Thomson) writes:
>> Currently most systems do some type checking at run time: what is a
>> divide-by-zero eroor trap except a type failure indication from the hardware
>0 is an integer, just like 17 is. Milner-style typechecking is structural,
>so it knows about, say, integers, but not about positive integers, primes,
>and non-structural entities of this kind.

Then perhaps some appropriate questions are:

	What is a type?
	What are types used for?

Should the type of an object exactly describe its possible values (Tom T), or
should types be coarse, well-known approximations (Nick R), such as integers,
thus making reasoning about the program simpler?

Maybe there are as many answers to these questions as there are programmers and
computer scientists...?

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Jonas Wallgren                                 |                 JWC@IDA.LiU.SE
Department of Computer and Information Science |
Linkoping University                           |-------------------------------
SE-581 83  Linkoping                           |
Sweden                                         |(\x.xx)(\x.x):(forall a.(a->a))
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