[ghc-steering-committee] Proposal #631: Set program exit code by main return type, recommendation: accept something

[Simon Marlow]

I think we can discount 1a because it doesn't satisfy the stability
principles, right?

Out of the others, I would probably go with 1b or 3a as the most
predictable behaviours. I also like Simon's (4) (gated by an extension,
that we hope to enable in GHC2027).

Cheers
Simon

On Tue, 26 Mar 2024 at 09:35, Arnaud Spiwack <arnaud.spiwack at tweag.io>
wrote:

> Alright, so here are the plausible alternatives
>
> 1a. New type-class-based behaviour without extension
> 1b. New type-class-based behaviour gated by an extension
> 2. Just a warning (when main isn't at type IO () or IO Void)
> 3a. A warning + the new type-class-based behaviour gated by an extension.
> With the extension, types that don't implement the type class raise an
> error.
> 3b. A warning + the new type-class-based behaviour gated by an extension.
> With the extension, types that don't implement the type class raise a
> warning (which could have a different phrasing than without the extension).
>
> Let's vote!
>
> On Fri, 22 Mar 2024 at 15:30, Malte Ott <malte.ott at maralorn.de> wrote:
>
>> On 2024-03-22 08:58, Arnaud Spiwack wrote:
>> > @Malte, in my opinion, with the extension on, types which are not
>> covered
>> > by the type class should error out.
>>
>> Ah, I see. Well, I am fine either way.
>>
>> I just don’t see much value in deciding for the user which code problems
>> are
>> unacceptable. Especially since this will make the corresponding language
>> extension more breaking and thus harder to make the default.
>> Others have voiced similar opinions in the GitHub thread.
>>
>> Best
>> Malte
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>
>
> --
> Arnaud Spiwack
> Director, Research at https://moduscreate.com and https://tweag.io.
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