recursion/iterator question

["Tato Thetza" <thetza@sent.com>]

Hi caml-list
Given a list, I would like to iterate over all triplets in the list. For
example, in mathematcs, its not uncommon to have expressions such as
"for all i,j,k in set X, do f(i,j,k)"

The only way I can think of is to create a list with all triplets of the
list, so:
  triplets([1,2,3,4]) = [(1,2,3),(1,2,4),(1,3,4),(2,3,4)]
and take this list and map a function f to it.

questions: 
1) what would be the best way to write triplets?
2) is there a cleaner way to iterate over all triplets in a list?

please excuse my english
Tato T.