From: Martin Jambon <martin.jambon@ens-lyon.org>
To: Florent.Ouchet@imag.fr
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] integer regular expressions
Date: Tue, 31 Mar 2009 04:10:55 +0200 [thread overview]
Message-ID: <49D17BAF.1060702@ens-lyon.org> (raw)
In-Reply-To: <20090330192129.32152seaqvtmfb15@webmail.imag.fr>
Florent.Ouchet@imag.fr wrote:
> Hello,
>
> I'm looking for a way to match integer numbers (immediate values), whose
> types may be either int, int32, int64 or big_int. A conversion to string
> in order to use string (perl compatible) regular expressions is likely
> not the solution I'm looking for because it will not allow integer
> specific matches.
>
> For instance (not normative), the regular expression syntax and
> semantics would allow complex matches such as "0%30" === "this integer
> matches if and only if its modulo to 30 is equal to 0". As in string
> regular expressions, operator | will implement a logical or...
>
> I googled a little but all the results are always related to string
> regular expressions :( any pointers? any existing Caml code?
You want something called "views" or "active patterns".
You can do that in OCaml with mikmatch, which includes such syntax extension.
See http://martin.jambon.free.fr/mikmatch-manual.html#htoc10
Here is your example:
let view Mod30 = fun x -> x mod 30 = 0
(*
but not:
let view Mod m = fun x -> x mod m = 0
but it could be implemented without difficulty (if really needed).
*)
let test x =
match x with
%Mod30 -> ...
| ... ->
Of course the whole point is to use %Mod30 within arbitrary patterns,
otherwise it wouldn't be useful.
I you want to match regular expressions over anything else than bytes, there's
nothing out-of-the-box. You can define views on lists that would consume any
number of elements, but it is pretty limited.
Martin
--
http://mjambon.com/
next prev parent reply other threads:[~2009-03-31 2:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-30 17:21 Florent.Ouchet
2009-03-31 2:10 ` Martin Jambon [this message]
2009-03-31 9:11 ` [Caml-list] " Florent Ouchet
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