Question about the portability of containers

David Feuer david.feuer at
Tue Jun 9 07:58:26 UTC 2020

Sorry, I got busy with other things and didn't finish following up on that
PR. The Applicative/Monad thing will be cleared up automatically whenever
we drop support for GHC 7.8. It's hard to imagine a future Haskell
implementation without AMP.

On Tue, Jun 9, 2020, 3:44 AM Julian Ospald <hasufell at> wrote:

> Portability is the reason I stopped caring about my containers PR, which
> is a very minor addition. I have no concrete input on what to do either,
> even after several pings, so I gave up.
> My view on this is: if it makes people stop contributing, it is not worth
> it for something I don't even see a real world use case for, only
> theoretical ones.
> On June 8, 2020 4:46:17 AM UTC, David Feuer <david.feuer at> wrote:
>> I really *wish* we had another viable and relevant Haskell
>> implementation we could test against. That would be *great*. The
>> containers package is quite venerable, long predating my own
>> involvement. For its entire life, it has had a tradition of trying to
>> be portable. It seems somewhat sad to throw all that away. I believe
>> there *is* an alternative option, but it will require someone to put
>> in a significant amount of work to make it happen. The basic idea is
>> to replace direct checks for __GLASGOW_HASKELL__ with ones for our own
>> version of that. Normally, __OUR_GLASGOW_HASKELL__ will be equal to
>> __GLASGOW_HASKELL__, but we can also choose to leave it undefined
>> using a Cabal option or some such. That way, we can at least run CI
>> with our "non-GHC" code and make sure that it still works.
>> On Sun, Jun 7, 2020 at 10:59 PM Fumiaki Kinoshita <fumiexcel at> wrote:
>> >
>>>  I noticed that there are massive amount of CPP pragmas to switch code between GHC and non-GHC (e.g., and they are a burden for maintainers. Moreover, the non-GHC part of the codebase is untested due to the lack of viable alternative compilers (
>>>  Therefore I propose to revisit the policy for portability of core libraries. Portability is not a bad thing, but few people use other compilers these days. The drag is only likely to increase because there's no plan (AFAIK) for a new Haskell standard.
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