[ghc-steering-committee] #380 GHC2021: Forth status update / kialo.com

[Spiwack, Arnaud]

On Thu, Dec 17, 2020 at 5:24 PM Simon Marlow marlowsd at gmail.com
<http://mailto:marlowsd@gmail.com> wrote:

In the case of partial type signatures *you can't use the feature without
> generating a warning*, which is quite a different matter, I think. It
> would be even stranger if it was an error!
>
I’m not sure I follow, I can certainly use PartialTypeSignature without
generating a warning:

> :set -XPartialTypeSignatures
> :set -Wno-partial-type-signatures
> f :: _ -> _ ; f = (+) 1

Unless you are saying that the feature *is* the warning. Which is debatable.

If you think that the warning is the feature, though, then you have the
same feature without PartialTypeSignature, but as an error instead

> f :: _ -> _ ; f = (+) 1

<interactive>:2:6: error:
    * Found type wildcard `_' standing for `Integer'
      To use the inferred type, enable PartialTypeSignatures
    * In the type `_ -> _'
      In the type signature: f :: _ -> _

<interactive>:2:11: error:
    * Found type wildcard `_' standing for `Integer'
      To use the inferred type, enable PartialTypeSignatures
    * In the type `_ -> _'
      In the type signature: f :: _ -> _
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