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From: ridoux@irisa.fr (Olivier Ridoux)
Newsgroups: comp.lang.functional,comp.lang.prolog
Subject: Re: Pattern matching considered harmful
Message-ID: <1990Jun6.070938.735@irisa.fr>
Date: 6 Jun 90 07:09:38 GMT
References: <RJC.90Jun4134659@brodie.uk.ac.ed.cstr>
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From article <RJC.90Jun4134659@brodie.uk.ac.ed.cstr>, by rjc@uk.ac.ed.cstr (Richard Caley):
> It would be nice this was possible. declare a dtat type ad declare a
> `picture' of it which is what the outside world sees.
>  

Two already implemented extensions of Prolog can be used to support this
style of programming.  They are Lambda-Prolog [Miller & Nadathur in ILPC'86] 
and Login [Ait-Kaci & Nasr in JLP 3(86)].

Lambda-Prolog does the job by the means of higher-order terms and 
beta-reduction which act as well-behavied macros and macro-expansion.  
Login is more in the style of abstract data-types or object-oriented 
programming.

However both have been designed to extend the term domain and to have a
unification that performs tricky computations rather than to support a
software-engineering discipline.  They may lack the syntactic sugar that helps
enforcing the discipline.

Friendly,

Olivier Ridoux