What Haskell users are actively maintaining or deving software using ghc <8

[Henning Thielemann]

On Wed, 27 May 2020, Joseph C. Sible wrote:

> On Wed, May 27, 2020 at 11:09 AM Henning Thielemann
> <lemming at henning-thielemann.de> wrote:
>>
>> I use 7.4.2 regularly. I like to avoid upgrading to 7.10 and above because
>> I do not want to run into accidental bugs based on "maximum (a,b)".
>
> IMO, avoiding "instance Foldable ((,) a)" isn't really a good reason
> to not upgrade. You're giving up a lot of bug fixes and other
> improvements just to avoid accidentally writing code that a linter
> will easily catch.

I am not giving up anything, because I test my code against both 7.4.2 AND 
newer GHC versions.

What linter can easily catch "instance Foldable ((,) a)"?

GHC cannot warn about it, so far.

Another solution would be to separate 'base' from GHC. I could then work 
with a patched 'base' with forbidden "instance Foldable ((,) a)".