[Haskell-cafe] Fwd: constraint inference

[Dmitry Olshansky]

You are right, thanks!



2017-07-07 22:17 GMT+03:00 Li-yao Xia <lysxia at gmail.com>:

>
>
> On 07/07/2017 02:50 AM, Dmitry Olshansky wrote:
>
>> I am not sure why but when I didn't set RankNTypes I got an appropriate
>> error. So I specified it.
>>
>> But if I write
>>    let { f :: (forall n. KnownSymbol n => Proxy n) -> String; f p =
>> symbolVal p }
>> then nothing is changed.
>>
>>
>>
>
> What would the String (f Proxy) be? (Note that (Proxy :: forall n.
> KnownSymbol n => Proxy n) would be a valid argument here.)
>
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