I think this is the exact use case that the new ConstraintKinds extension
was meant to address (http://hackage.haskell.org/trac/ghc/wiki/Status/Oct11).
But we have to wait for 7.4.
-deech
On Thu, Nov 3, 2011 at 1:08 PM, Amy de Buitléir
Thank you, David and Antoine.
I was planning to have files containing different types of objects, but where all of the types are instances of a particular class. Since the class definition ensures that whatever the types are, they implement the methods that I need, I hoped to be able to manipulate the files using those methods, without having to find out the class programmatically.
Clearly I need to rethink this. I'm looking into existentially quantified data constructors now, maybe that will help.
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