Who needs Ord for Sets and Maps anyway?

[Okasaki, C. DR EECS]

[My sincere apologies for the multiple posts.  I forgot to include the
subject line on my previous post, which makes it unclickable in the
archive...]

I wrote:
> You've just highlighted why the collections hierarchy in Edison was a 
> lattice of 8 classes.  Basically, there are two choices in each of 
> three different dimensions:
>
>  1. The set/map distinction
>  2. Require Ord or don't (your first point above)  3. "Observable" or 
> not (your second point above)

Oops, I typed too fast.  Edison actually has two choices in each of four
different dimensions.  The first is the set/map distinction, but those
are in two separate class hierarchies.  Within each of those class
hierarchies, the three dimensions are Ord/not, Observable/not, and
"unique"/not, where the last dimension is the difference between sets
and bags.

-- Chris