Re: [Caml-list] Re: Metaprogramming features

["Nicolas Pouillard" <nicolas.pouillard@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 1219 bytes --]

Excerpts from jonathandeanharrop's message of Tue Oct 07 02:17:13 +0200 2008:
> On Monday 06 October 2008 17:46:49 Chung-chieh Shan wrote:
> > Jon Harrop <jonathandeanharrop@googlemail.com> wrote in article 
> <200810061656.42903.jon@ffconsultancy.com> in gmane.comp.lang.caml.inria:
> > > Exactly. The difference is (only) the performance characteristics.
> >
> > To the contrary, that is not the only difference; the timing of
> > side effects (including non-termination and exceptions) can also be
> > different.  We give an example at the beginning of our Section 2.
> 
> I don't follow. Your paper translates the following staged function:
> 
>   let power7 : int -> int =
>     .! .<fun x -> .~(Printf.printf "power\n"; power 7 .<x>.)>.;;
> 
> into this:
> 
>   let npower7 =
>     (fun () -> fun x -> (printf "power\n"; npower 7 (fun () -> x)) ()) ();;
> 
> and notes that the result is different because the former calls printf 
> immediately whereas the latter defers.
> 
> Surely the discrepancy is because the translation should be:
> 
>   let npower7 =
>     let e = printf "power\n"; npower 7 (fun () -> x) in
>     (fun () -> fun x -> e ()) ();;

Hum "unbound value x" :)

-- 
Nicolas Pouillard aka Ertai

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 194 bytes --]