AFAICT this bug fix http://hackage.haskell.org/trac/ghc/ticket/7239 did not
make it into 7.6.1. Also I am happily working on the Haskell Platform with
7.4.1 and I'd rather avoid upgrading if possible.
Is there a workaround? I've attached my code below along with the error message
(which is the
Hi Iavor,
Thanks much for the explanation.
Before this experiment with FDs, I was using a type family. I tried
switching to FDs, because I wanted the compiler to know that the family is
injective in order to assist type-checking. Can we declare type families to
be injective? Now I see that I ran
I presume that injectivity of type families is the sole reason why data
families exist.
Roman
* Conal Elliott co...@conal.net [2012-12-26 10:23:46-0800]
Hi Iavor,
Thanks much for the explanation.
Before this experiment with FDs, I was using a type family. I tried
switching to FDs,
I don't think that's true (though a few minutes of searching has not
yet turned up anything describing the original motivation for data
families). Sometimes you really do want to construct a family of new
data types, instead of just mapping to existing ones. I think
everyone agrees that using
* Brent Yorgey byor...@seas.upenn.edu [2012-12-26 14:49:16-0500]
I don't think that's true (though a few minutes of searching has not
yet turned up anything describing the original motivation for data
families). Sometimes you really do want to construct a family of new
data types, instead of
