Hi, On 2015-10-06 at 21:32:19 +0200, Mikhail Glushenkov wrote:

On 6 October 2015 at 19:03, Herbert Valerio Riedel wrote:

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In the specific case of MRP, I can offer you a Wall-perfect transition scheme by either using `ghc-options: -fno-mrp-warnings` in your cabal-file, [...]

Apropos, is there a similar option for AMP warnings? I would rather use that than CPP.

Sure, added in GHC 7.8: | In GHC 7.10, Applicative will become a superclass of Monad, | potentially breaking a lot of user code. To ease this transition, GHC | now generates warnings when definitions conflict with the | Applicative-Monad Proposal (AMP). | | A warning is emitted if a type is an instance of Monad but not of | Applicative, MonadPlus but not Alternative, and when a local function | named join, <*> or pure is defined. | | The warnings are enabled by default, and can be controlled using the | new flag -f[no-]warn-amp. However, if you use that now with GHC 7.10 you get a warning: | $ ghc-7.10.2 -fno-warn-amp | | on the commandline: Warning: | -fno-warn-amp is deprecated: it has no effect, and will be removed in GHC 7.12 so you you'll need to guard that with something like if impl(ghc == 7.8.*) ghc-options: -fno-warn-amp