[Haskell-cafe] GHC 8.8 and MonadFail proposal

Branimir Maksimovic branimir.maksimovic at gmail.com
Wed Apr 17 04:47:41 UTC 2019

That's always like that. I build packages from git in such cases.
You remind me to build new ghc now ;)


On 4/17/19 6:39 AM, Kazu Yamamoto (山本和彦) wrote:
> Hello,
> I built the GHC 8.8 branch and tried to use it. I was very surprised
> because many packages cannot be built due to the removal of the "fail"
> method from the Monad typeclass.
> GHC 8.6 (with -Wcompat) does not warn even if "fail" is defined.  I
> had no chance to notice this change. Isn't this change too radical?
> The same thing happened in GHC 8.4 due to Semigroup. I could not
> notice this change beforehand because I did not know the "-Wcompat"
> option. In my opinion, we should have included "-Wcampat" in "-Wall".
> Anyway, if I understand correctly, "-Wcompat" does not help in
> the MonadFail case.
> I'm a fan of both proposal. But I feel that no period of warnings
> is not a good approach.
> --Kazu
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