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From: Xavier Leroy <Xavier.Leroy@inria.fr>
To: David.Bulone@ulp.u-strasbg.fr
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Récursivité terminale
Date: Thu, 26 Mar 2009 15:59:32 +0100	[thread overview]
Message-ID: <49CB9854.1020707@inria.fr> (raw)
In-Reply-To: <20090326153839.8kzcsd6k0sg0csoc@webmail.u-strasbg.fr>

>   Je voudrais savoir s'il existait un moyen de transformer une fonction 
> récursive non terminale en fonction récursive terminale avec Caml.

[ Translation: is there a way to transform a non-tail-recursive function
   into a tail-recursive function? ]

A technique that always works is to convert your function to
continuation-passing style.  The resulting code is hard to read and
not particularly efficient, though.

It is possible to do better in a number of specific cases.  Functions
operating over lists can often be made tail-rec by adding an
"accumulator" parameter and reversing the accumulator at the end.
For instance, List.map f l (not tail-rec) can be rewritten as
List.rev (List.rev_map f l) (tail-rec).

For more complex data structures than lists, Huet's zippers can often
be used for the same purpose.

Happy Googling,

- Xavier Leroy


  reply	other threads:[~2009-03-26 14:59 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-03-26 14:38 David.Bulone
2009-03-26 14:59 ` Xavier Leroy [this message]
2009-03-27  3:37   ` Chung-chieh Shan

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