Newsgroups: comp.lang.misc
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uupsi!ficc!peter
From: peter@ficc.ferranti.com (Peter da Silva)
Subject: Re: Formal definitions (Re: ada-c++ productivity)
Message-ID: <-WRADPH@xds13.ferranti.com>
Reply-To: peter@ficc.ferranti.com (Peter da Silva)
Organization: Xenix Support, FICC
References: <1954@optima.cs.arizona.edu> <1991Apr16.130341.27345@kodak.kodak.com>
Date: Tue, 16 Apr 91 19:19:16 GMT

Taking a quick flip-flop, here:

In article <1991Apr16.130341.27345@kodak.kodak.com> cok@islsun.Kodak.COM (David Cok) writes:
> [a specification language] says nothing about the method used
> to achieve that.  Indeed there are many methods (algorithms) for sorting.
> Some of them are quite complex in order to achieve some desired level of
> performance.  Different ones will be applicable in different situations.

Yes, and you need to specify a bit about the behaviour of the sort:
does it retain the order of non-sorted fields, for example? In any case,
how does this differ from top-down programming, where you say:

	sort frammistan

and later on fill in sort with code (or pull an appropriate routine from
a library). I have no idea how the UNIX 'sort' program works... does that
make the following shell script a formal pecification?

	awk -F: '{print $1}' /etc/passwd | sort | uniq -c

In fact I know nothing about what algorithms are used by uniq, sort, or awk.
A great advantage of higher level languages is that you no longer have to
deal with the implementation details of larger and larger components of
the solution.
-- 
Peter da Silva.  `-_-'  peter@ferranti.com
+1 713 274 5180.  'U`  "Have you hugged your wolf today?"