[ghc-steering-committee] Wrapping up Constructor Synonyms and Pattern Synonym Signatures

[Simon Marlow]

Agree, I'm in favour of the conservative version of #42 and against #41.

But #42 also has a proposal for inference of the constructor type in the
absence of a type signature, and gives several options there.  I presume we
want to be conservative and say that we're not making any changes to the
behaviour in the absence of a type signature, right?

Cheers
Simon

On 9 April 2017 at 21:16, Christopher Allen <cma at bitemyapp.com> wrote:

> Thank you to those of you that replied. I'd like to preserve the
> syntactic distinction that construction synonyms eliminates. Your
> statements have shifted me to a reject on
> https://github.com/ghc-proposals/ghc-proposals/pull/41
>
> If no one has objections, I'd like to move to a reject as I think
> enough time has elapsed that it's unlikely to get any defenders. Speak
> up if you feel something was missed.
>
>
> Regarding https://github.com/ghc-proposals/ghc-proposals/pull/42
>
> Summarizing peoples' replies so far:
>
> Joachim: In favor, as long as :i does the right thing. Seems
> under-specified, suggested the following possible relationships
> between signature of the pattern and the constructor:
>
> * May not differ in anything but the constraints.
> * Must have the same return type.
> * Must have the same outer type constructor in their return type.
> * No relation.
>
> Roman: In favor of this proposal under the "May not differ in anything
> but the constraints" policy and against it under any of the other
> three.
>
> Simon PJ: In favor of #42 alone, but no holes. Agrees with Roman that
> that type of the constructor should be the same as that of the
> pattern.
>
> Simon Marlow: I believe the statement was in favor of #42 contra #41,
> but I didn't get a sense of how strongly or how Simon felt about the
> particulars.
>
>
> I agree with and want to highlight Roman's point regarding,
>
> >A looser relationship between the constructor function and the pattern
> makes code significantly harder to read and the proposal doesn't include
> any justification for such a looser relationship so I would go with the
> strongest requirement possible.
>
>
> It seems to me like the respondents so far are in favor of #42, but
> want the strongest variant. I'd like to move to accept #42 with the
> "May not differ in anything but the constraints" variant. Any
> objections?
>
>
> Thank you Joachim for the status update last week.
>
> Thanks you for your time everyone,
> Chris Allen
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