On Fri, Feb 15, 2008 at 10:18:04AM -0800, Jason Dagit wrote:
> Sun Feb 10 01:00:34 PST 2008 Jason Dagit <[EMAIL PROTECTED]>
> * make Hopefully have type witnesses
Thanks! This looks good, but I've got one question...
> \begin{code}
> -get_common_and_uncommon :: RepoPatch p => (PatchSet p C(x),PatchSet p C(y))
> ->
> - ([PatchInfo],(RL (RL (PatchInfoAnd p)) :\/: RL
> (RL (PatchInfoAnd p))) C(x y))
> -get_common_and_uncommon_or_missing :: RepoPatch p => (PatchSet p
> C(x),PatchSet p C(y)) ->
> - Either PatchInfo ([PatchInfo],(RL (RL
> (PatchInfoAnd p)) :\/: RL (RL (PatchInfoAnd p))) C(x y))
> +get_common_and_uncommon :: (RepoPatch p, (Invert (PatchInfoAnd p)))
> + => (PatchSet p C(x),PatchSet p C(y))
> + -> ([PatchInfo],(RL (RL (PatchInfoAnd p)) :\/: RL
> (RL (PatchInfoAnd p))) C(x y))
> +get_common_and_uncommon_or_missing :: (RepoPatch p, (Invert (PatchInfoAnd
> p)))
> + => (PatchSet p C(x),PatchSet p C(y))
> + -> Either PatchInfo ([PatchInfo],(RL (RL
> (PatchInfoAnd p)) :\/: RL (RL (PatchInfoAnd p))) C(x y))
Why is this Invert instance required here? It seems to me like the compiler
ought to be able to infer from RepoPatch p that (Invert (PatchInfoAnd
p))...
I haven't actually looked into why this instance isn't inferred, since I
thought I'd run it by you first.
--
David Roundy
Department of Physics
Oregon State University
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