ketil+haskell at ii.uib.no
Tue Mar 16 14:20:39 EST 2004
JP Bernardy <jyp_7 at yahoo.com> writes:
> You argued that Eq is (nearly) always
> assumed to be defined by structural equality, so "Bag"
> would be just as good as "MultiSet".
I think you're saying we might need a bag to hold items where we want
to group things according to (equivalence on) some arbitrary key?
Perhaps we could have the bag datatype parametrised over a
user-supplied ordering, so that
would be equivalent to a
Bag compare a (with compare :: a -> a -> Ordering)
The bag could then hold regular (Eq-based) Sets of items.
Would this make sense? Would it be useful?
If I haven't seen further, it is by standing in the footprints of giants
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