Great! I'll take a whack at it ;) On Tue, Apr 17, 2012 at 4:07 PM, Edward Kmett <ekm...@gmail.com> wrote: > > > On Mon, Apr 16, 2012 at 6:57 PM, Nicolas Frisby <nicolas.fri...@gmail.com> > wrote: >> >> I'm simulating skolem variables in order to fake universal >> quantification in constraints via unsafeCoerce. >> >> http://hpaste.org/67121 >> >> I'm not familiar with various categories of types from the run-time's >> perspective, but I'd be surprised if there were NOT a way to use this >> code to create run-time errors. >> >> Is there a way to make it safer? Perhaps by making Skolem act more >> like GHC's Any type? Or perhaps like the -> type? I'd like to learn >> about the varieties of types from the run-time's perspective. > > > FWIW- I have a version of this concept packaged up in the constraints > package. > > I had a small example that abused flexible instances and MPTCs to cause the > single Skolem version of my code to fail. > > However, when I refined it to use two Skolem variables I wasn't able to > derive sufficient Oleggery to break it. That said, an absence of a > counter-example isn't a proof that it can't exist. > > http://hackage.haskell.org/packages/archive/constraints/0.3/doc/html/src/Data-Constraint-Forall.html >
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