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Re: Pattern matching issues


From: Panicz Maciej Godek
Subject: Re: Pattern matching issues
Date: Wed, 13 Jul 2011 12:42:09 +0200

2011/7/13 Marco Maggi <address@hidden>:
> Panicz Maciej Godek wrote:
>
>> I've been  wondering if there  is a way to  represent this
>> sort of pattern for the pattern matcher provided by Wright
>> (and Guile).
>
> The syntax should be something like:
>
> (match '(Mr Hulot and I need a vacation)
>  ((?x ... 'need ?y ...)
>   (write (list ?x ?y))
>   (newline)))
>
> but at  present multiple ellipses  are not supported  at the
> same level  (that is in the  same list or  the same vector).
> It is  possible to do  it, but a  policy (greedy/non-greedy)
> must  be  adopted  to  solve  ambiguous cases  and  it  gets
> complicated.

I agree that it could get complicated for the ambiguous cases,
but it should at least be possible for the simple ones. I think that
the lack of this capability is a serious limitation of a pattern
matcher. I'm not well acquainted with regular expressions, but
I could try to resolve this issue upon the book that I'm currently
reading -- provided that there's no one dealing with it at the
moment

Regards
M.



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