Proposal: Bounded instance for IntSet (ticket #1953)

John Meacham john at
Sun Dec 2 19:37:23 EST 2007

On Sun, Dec 02, 2007 at 03:45:40PM -0800, David Benbennick wrote:
> >From :
> I propose to add a Bounded instance to IntSet.hs.
> IntSet is in Ord, and there are only finitely many instances of
> IntSet. Therefore there is a min IntSet and a max IntSet. It turns out
> these bounds are very simple:
> instance Bounded IntSet where
>     minBound = empty
>     maxBound = singleton maxBound

This seems fairly unintuitive me. the natural choices of minimum and
maximum bounds for a set would seem to be

singleton minBound vs singleton maxBound


empty vs universal (fromList [minBound .. maxBound]) set

the odd combination of the two proposed just feels off to me.


John Meacham - ⑆⑆john⑈

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