help from the community?

John Meacham john at
Sat Feb 3 17:13:28 EST 2007

On Mon, Jan 29, 2007 at 10:08:59AM +0100, Andres Loeh wrote:
> > >I didn't fully understand this requirement.  If Haskell-prime gets
> > >rank-2 or rank-n types, then do we need to restrict constructors in this
> > >way?
> Ok, this really boils down to the question of whether we do rank-2 or
> rank-n types. I'm biased, because I actually use rank-n types
> frequently, and feel somewhat limited by the rank-2 restrictions.  I
> don't know how many people actually do, though. I can understand
> Iavor's points that rank-2 might be easier to explain, but at least
> GHC's rank-n extension has a very detailed paper explaining it, so I
> guess it's one of the better documented extensions.

I would say there is not much point in doing just rank-2. Once you know
how to do rank-n (and we do, thanks to SPJ's great paper) then it is
just as easy to implement as rank-2. Perhaps even moreso since it is a
rather elegant general change to the type inferencer rather than a
special case.


John Meacham - ⑆⑆john⑈

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