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