[Haskell-cafe] Monad of no `return` Proposal (MRP): Moving `return` out of `Monad`

[Mario Blažević]

On 15-10-09 10:32 AM, Taru Karttunen wrote:
> On 09.10 08:57, Mario Blažević wrote:
>> ...
>> on ghc-7.10 branch
>>
>>     version: my-package-1.7.2.710
>>     build-depends: ghc == 7.10.*,
>>
>> ...
>
> And then GHC 8.0 is released and your library is broken until you
> update the cabal file or add a new branch. Which means that all
> libraries depending on your library refuse to build...
>
> This would mean that all libraries would need a new release
> on each GHC major version? Oh and testing your library on
> HEAD before release? Not supported? Using any library depending
> on your library before the release?

	Relax. Take a deep breath.

	The above branching scheme extends the PVP guidance to GHC as well; 
which is to say, it assumes every major GHC release to have a potential 
to break your package. But if you trust that GHC 8.0 will be backward 
compatible with 7.10 as far as your code goes, you can change the same 
.cabal file to

 >> on ghc-7.10 branch
 >>
 >>     version: my-package-1.7.2.710
 >>     build-depends: ghc >= 7.10 && < 8.1,


and if you're confident that GHC will *never* break your code again, you 
can even have

 >> on ghc-forever branch
 >>
 >> version: my-package-1.7.2.0
 >> build-depends: ghc >= 7.10