Proposal for Max/Min Monoids Trac ticket 3036

David Menendez dave at
Fri Feb 20 00:00:38 EST 2009

I like the Min/Max monoids, and the possibility of adding something
like AddBounds (although I'd prefer a name like "Bounded"; "Bounded
Integer" reads better than "AddBounds Integer").

One possible snag is that, so far as I know, there's no explicit
requirement that a type that instantiates Ord and Bounded should
satisfy the laws,

    min maxBound a = a = min a maxBound
    max minBound a = a = max a minBound

We're just assuming (reasonably) that instances will always work out
that way. (Although, I guess we're making the same assumption with Sum
and Prod.)

Dave Menendez <dave at>

More information about the Libraries mailing list