[erlang-questions] working with sets

Vance Shipley <>
Fri Jan 4 01:38:09 CET 2008


On Thu, Jan 03, 2008 at 03:06:08PM -0800, Michael McDaniel wrote:
}  Seems like the sets module could help out.

I could use the sets module but I have to maintain an array myself.

   1> Set1 = sets:from_list([1,2,3]),
   1> Set2 = sets:from_list([4,5,6]),
   1> Set3 = sets:from_list([7,8,9]),
   1> Set = sets:from_list(Set1,Set2,Set3]).

   2> sets:is_element(1, Set).
   false
   3> sets:is_element(Set1, Set).
   true

   4> sets:fold(fun(E, false) -> sets:is_element(9, E) end, false, Set).
   true
   5> sets:fold(fun(E, false) -> sets:is_element(10, E) end, false, Set).
   false

So sure, I could manage a set of sets by rolling my own with the sets
module however I could do that with lists as well and it would be much
smaller than a set().  The sofs module sounds like it's what I should
be looking at however I can't see how it helps yet.

	-Vance

I should really get that Okasaki book ... 



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