On Fri, Jun 03, 2011 at 11:49:01PM -0800, Christopher Howard wrote:
On 06/03/2011 11:37 PM, Christopher Howard wrote:
Weird request: For a certain application, the "nub" function from Data.List is exactly what I need... almost. Nub removes duplicates, keeping the /first/ occurrence of each element. However, I need a function that removes duplicates, keeping the /second/ occurrence of each element. There wouldn't happen to be a function already that does this, would there?
I'm working with a custom type which is a member of Eq, but some of the data in the type is not used in the comparison. So it is important which of the two "duplicates" are actually saved.
I should qualify this: By "second" I mean "last". Of course, it is possible for there to be more than one duplicate of any given element in a list. E.g., if there are three identical elements in a list, I want the third one, not the second one.
In that case, can't you simply revert the list, nub it, then revert again (i.e. reverse . nub . reverse)? regards, iustin