[ghc-steering-committee] #632: Phased introduction of GHC2024

[Simon Peyton Jones]

I really want ghci to use the latest and greatest language edition.


I think we agree about this

I also would prefer it to be used when calling ghc on a quick test file.
If deemed necessary we can throw a warning when we fallback to a default in
that case.


Ah, but now we are on the slippery slope.  Your "quick test file" may well
become a little script you use every day... and it may then suddenly stop
working when you install a new GHC with a new default language edition.  We
don't want that!  And it is completely solved by saying that we never
change the default language edition for .hs modules -- if it works now
it'll work in the future because we always fall back to the same language
edition. (e.g Hsakell98 or GHC2021 or whatever).

In some ways Hakell98 is better: it's very stable; and it is so old that
it'll encourage you to put a one-line {-# LANGUAGE GHC2024 #-} at the top
of your module to make it self-describing.   I love self-describing files
:-)

I wonder if this debate would be better on the GitHub discussion thread?
I'd love to hear from more people.

Simon

On Fri, 22 Mar 2024 at 14:42, Malte Ott <malte.ott at maralorn.de> wrote:

> I also think that the notion of default-language matters. For some reason
> people
> care greatly about which is the "real" Haskell.
>
> I really want ghci to use the latest and greatest language edition.
> I also would prefer it to be used when calling ghc on a quick test file.
> If deemed necessary we can throw a warning when we fallback to a default in
> that case.
>
> I think it is very important that we care about breakage for the sake of
> the
> ecosystem. But the ecosystem relies on Cabal to build packages so outside
> of
> that changes have another quality.
>
> Best
> Malte
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