Ross Paterson wrote:

(This would have been easier to read as a single patch.)

Yes. Sorry. I'm still learning Darcs.

This code could easily be made Haskell 98:

[Minor points deleted] Agreed. I'll incorporate your suggestions into the next patch.

Since this is basically Haskell 98, and is cleanly separated from the modules of base, it looks like a prime candidate for a separate package, especially as the plan is to slim down base package (#710).

I see your point about not bringing it into base, but on the other hand its a bit small to float off as as separate package. Having many tiny packages can make finding the right functionality just as hard as a few bloated ones. I've had a look at #710, and it looks like ranged sets would belong in the containers section. Paul.