Puzzle

Puzzle

[David Thomas]

I have three lists that I would like to have sorted
through user interaction.  I can, of course, say
"List.sort ask list" for each list.  What if, however,
rather than sorting each list in turn, I wanted the
questions to be interleaved, either randomly or in a
prespecified sequence?  Is it possible to do this
without reimplementing sort?  I easily could, but it
seems more fun without...

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Re: [Caml-list] Puzzle

[Christophe Raffalli]

David Thomas a écrit :
> I have three lists that I would like to have sorted
> through user interaction.  I can, of course, say
> "List.sort ask list" for each list.  What if, however,
> rather than sorting each list in turn, I wanted the
> questions to be interleaved, either randomly or in a
> prespecified sequence?  Is it possible to do this
> without reimplementing sort?  I easily could, but it
> seems more fun without...
> 

This should work (I did not test ...), But the input output may
not work, One should have a separate thread to interact with the user
and the sorting thread sending request to this thread ... but you may 
assume all this is done by the ask function.

let tsort l =
   let r = ref [] in
   let g l = r := List.sort ask l in
   let th = Thread.create g l in
   th, r

let result =
   let th1, r1 = tsort l1 in
   let th2, r2 = tsort l2 in
   let th3, r3 = tsort l3 in
   Thread.join th1;
   Thread.join th2;
   Thread.join th3;
   !r1, !r2, !r3



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Re: [Caml-list] Puzzle

[Berke Durak]

On Fri, Aug 26, 2005 at 12:21:17PM -0700, David Thomas wrote:
> I have three lists that I would like to have sorted
> through user interaction.  I can, of course, say
> "List.sort ask list" for each list.  What if, however,
> rather than sorting each list in turn, I wanted the
> questions to be interleaved, either randomly or in a
> prespecified sequence?  Is it possible to do this
> without reimplementing sort?  I easily could, but it
> seems more fun without...

Of course, you could first ask all the questions to the user and store the
answers, then use List.sort.
-- 
Berke Durak