[Caml-list] lazy computation problem

[Pietro Abate <Pietro.Abate@anu.edu.au>]

Hi all.
I'm trying to learn how to programm lazily, but I'm kinda stuck.
I've a list, say let l = [[1;2;3];[4;5];[6;7;8]] and I want to
produce all possibile permutations (1,4,6) (1,4,7) (1,4,8) (1,5,6)
(1,5,7) ...

it can easily be done with List.iter and a couple of recoursive steps,
but I'm trying to code it in a tail-recoursive style and using lazy
evaluation. Hence my problem is to write a function that gets the list
and gives me back one result (1,4,6) and a lazy structure that encode
the rest of the computation... I looked at lazy streams or lazy lists to
solve this problem, but I was unable to come up with any nice
solution...

does anybody have any hints ?

p

ps: this problem is a stripped down version of a more complicated one
that involves big data structures, that's why I'm trying to come up with
an optimized solution.

-- 
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   I just watch what they do. Andrew Carnegie (1835-1919).
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