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From: Jon Harrop <jon@ffconsultancy.com>
Organization: Flying Frog Consultancy Ltd.
To: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Circuralizing lists
Date: Mon, 26 Nov 2007 22:41:49 +0000
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X-Spam: no; 0.00; failwith:01 ocaml:01 recursive:01 46,:98 frog:98 closures:01 wrote:01 rec:01 rec:01 caml-list:01 lazy:02 construct:02 static:03 let:03 let:03 

On Monday 26 November 2007 21:46, Till Varoquaux wrote:
> Writing the list containing an inifinite number of ones can easily be done
> as:
>
> let rec ones = 1::ones
>
> I however don't know of any type safe to generate the infinite list
> which is the repetition of a given list (in a type safe non lazy way).
> What I'm looking for is a code that would do:
>
> let circularize  = function
>
>     | [] -> failwith "cannot circularize empty lists"
>     | l -> let rec res = l@res in res
>
> Is this at all possible?

OCaml only permits restricted static forms of this construct. The only 
practical application of this restricted form that I am aware of is in 
avoiding dummy values when creating simple cycles such as the environments of 
recursive closures in an interpreter.

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/products/?e