Uniquable RdrName instance

[Carter Schonwald]

would making arrow remindable involve dropping the arr == haksell functions
assumption or doing something that would allow generalized arrows?


On Mon, Jun 16, 2014 at 5:14 PM, Nicolas Frisby <nicolas.frisby at gmail.com>
wrote:

> FYI it's #7828, not #7282.
>
> Jan, I'm very glad you're working on this. Thanks!
>
>
> On Mon, Jun 16, 2014 at 2:33 PM, Jan Stolarek <jan.stolarek at p.lodz.pl>
> wrote:
>
>> > Why do you want this? The danger I see lurking is that you might find
>> two
>> > RdrNames that give the same answer to getUnique but represent different
>> Yes, that's exactly my concern.
>>
>> > Why do you want this?
>> I'm working on #7282 - RebindableSyntax and Arrows. Here's a snippet from
>> desugaring of arrow
>> notation:
>>
>> leaves = concatMap leavesMatch matches
>>  where
>>    leavesMatch :: LMatch Id (Located (body Id)) -> [(Located (body Id),
>> IdSet)]
>>    leavesMatch (L _ (Match pats _ (GRHSs grhss binds)))
>>          = let defined_vars = mkVarSet (collectPatsBinders pats)
>> `unionVarSet`
>>                                           mkVarSet (collectLocalBinders
>> binds)
>>              in  [(body, mkVarSet (collectLStmtsBinders stmts)
>> `unionVarSet` defined_vars) | L _
>> (GRHS stmts body) <- grhss]
>>
>> This is in the desugarer. But I need to also know `length leaves` at the
>> renaming stage, which
>> means I need to call `concatMap leavesMatch matches`. The problem is that
>> in the renamer my
>> datatypes are not parametrised by `Id`. I turned `Id` into a type
>> parameter `id`, but then I
>> can't use VarSets. I could use more general UniqueSets but only if `id`
>> type parameter is an
>> instance of Uniquable. And since in the renamer the datatypes are
>> parametrized with RdrName this
>> leads me to wanting Uniqable RdrName instance.
>>
>> Janek
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>>
>
>
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