[Haskell-cafe] Equality constraints in type families
hpacheco at gmail.com
Sun Mar 30 00:14:08 EDT 2008
On Sun, Mar 30, 2008 at 3:54 AM, Manuel M T Chakravarty <
chak at cse.unsw.edu.au> wrote:
> Hugo Pacheco:
> > Yes, but doesn't the confluence problem only occur for type synonyms
> > that ignore one or more of the parameters? If so, this could be
> > checked...
> You can't check this easily (for the general case).
I was most interested in knowing that this assumption was enough, and it
looks like it does.
> type family G a b
> type FList a x = G a x
> type instance F [a] = FList a
> Does FList ignore its second argument? Depends on the type instances
> of G.
I haven't thought of that, thanks for the example.
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