Keith Wansbrough
Tue, 30 Jul 2002 18:01:31 +0100

> Designers of FiniteMap and Set (it's me again),
> I wish "keysFM" would yield "Set key" rather than "[key]"!
> Could such an implementation take constant time (by simply ignoring
> "elts")?

IIRC a Set key is simply a FiniteMap key key.  So what you require is
simply a mapFM (\k v -> k).

Correct me if I'm wrong...

--KW 8-)