flexible contexts and context reduction
ganesh.sittampalam at credit-suisse.com
Thu Mar 27 11:48:05 EDT 2008
> > Because I want to be able to make Foo values where the parameter type
> > isn't in Ord, too. I just want unFoo to work on specific Foo values where it is.
> but your recursive function requires a recursive constraint, which your data
> type does not guarantee byconstruction, and which the Ord instances do not guarantee
> due to lack of closed classes.
Yeah. As you imply, I'm probably out of luck.
> a rather pedestrian approach would record during construction whether or not
> all parts are in Ord (see below).
Unfortunately I need a (fully) polymorphic construction function, so this isn't
possible. I'm trying to generalise the trick described at http://hsenag.livejournal.com/11803.html
to arrows, but getting stuck with the "first" combinator.
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