Re: Definable operators

David Rush <kumo@intercenter.net>
20 Apr 1997 12:15:44 -0400

          From comp.compilers

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[19 earlier articles]
Re: Definable operators dlester@cs.man.ac.uk (1997-04-16)
Re: Definable operators fanf@lspace.org (Tony Finch) (1997-04-18)
Re: Definable operators monnier+/news/comp/compilers@tequila.cs.yale.edu (Stefan Monnier) (1997-04-18)
Re: Definable operators burley@tweedledumb.cygnus.com (Craig Burley) (1997-04-18)
Re: Definable operators apardon@rc4.vub.ac.be (1997-04-20)
Re: Definable operators genew@vip.net (1997-04-20)
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Re: Definable operators burley@tweedledumb.cygnus.com (Craig Burley) (1997-04-22)
Re: Definable operators burley@tweedledumb.cygnus.com (Craig Burley) (1997-04-30)
Re: Definable operators hrubin@stat.purdue.edu (1997-04-30)
Re: Definable operators apardon@rc4.vub.ac.be (1997-05-04)
Re: Definable operators Dave@occl-cam.demon.co.uk (Dave Lloyd) (1997-05-04)
Re: Definable operators ephram@ear.Psych.Berkeley.EDU (Ephram Cohen) (1997-05-06)
[13 later articles]
| List of all articles for this month |

From: David Rush <kumo@intercenter.net>
Newsgroups: comp.compilers,comp.lang.misc,comp.lang.functional
Date: 20 Apr 1997 12:15:44 -0400
Organization: Not Very
References: 97-03-037 97-03-076 97-03-112 97-03-115 97-03-141 97-03-162 97-03-184 97-04-027
Keywords: syntax, design

Craig Burley <burley@gnu.ai.mit.edu> writes amidst snipping and maiming:
> It's not clear to everyone what it means. Why wouldn't
> "1" + "2"
> evaluate to
> "3"
> for example?
>
> The concept of + always meaning the mathematical sense of addition is
> useful -- not just in the sense that "addition is useful", but that "+
> means _only_ addition" is useful in designing programming languages.
> In point of fact, "+ means _only_ addition" is _substantially_ more
> useful as a language feature than "+ means whatever the programmer
> wants it to mean".


How about "+" meaning the mathematical "+" defining a (semi?) group?
For "+" as string concatenation, that almost makes sense, although I
will admit that coming up with an inverse under "+" for string
concatenation is rather difficult.


Actually, under those constraints, the quasi-numerical implementation
of strings makes a lot of sense...


I don't know if I'm agreeing or disagreeing, here. But I think that
"+" denotes a behavior that "makes sense" only in relationship to
other behaviors applicable to a given type. I geuss I come in with a
little weaker constraint than Craig, but in basic agreement.


                happy hackin'


                david rush
                mailto:kumo@intercenter.net
--


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