On Mon, Apr 16, 2012 at 6:57 PM, Nicolas Frisby
<nicolas.frisby@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.