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From: Chris.Holt@newcastle.ac.uk (Chris Holt)
Newsgroups: comp.lang.functional,comp.lang.prolog
Subject: Re: Pattern matching considered harmful
Message-ID: <1990Jun5.175706.415@newcastle.ac.uk>
Date: 5 Jun 90 17:57:06 GMT
References: <2584@skye.ed.ac.uk> <3077@goanna.cs.rmit.oz.au> <2790@syma.sussex.ac.uk> <RJC.90Jun4134659@brodie.uk.ac.ed.cstr>
Sender: news@newcastle.ac.uk
Organization: Computing Laboratory, U of Newcastle upon Tyne, UK NE17RU
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In article <RJC.90Jun4134659@brodie.uk.ac.ed.cstr> rjc@uk.ac.ed.cstr (Richard Caley) writes:
>
>One can change the implementation of a function without changing its
>calling sequence, one can not change the structure of a data object
>without changing the pattern used to match it.
>
>It would be nice this was possible. declare a dtat type ad declare a
>`picture' of it which is what the outside world sees.

The picture is surely just those functions that can take the data type
as an argument, and those that can return the data type as a result.
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 Chris.Holt@newcastle.ac.uk      Computing Lab, U of Newcastle upon Tyne, UK
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 "...for where we are is here, And where here is, must we ever be."