Re: GHC 9.6.1 rejects previously working code

Out of curiosity, why do you require the `MonadIO` on the `Monad` instance? On 4/12/23 12:42, Harendra Kumar wrote: Thanks Tom and Rodrigo. That clarifies the problem. We will need to think which solution makes better sense. On Wed, 12 Apr 2023 at 15:01, Rodrigo Mesquita wrote:

Re: GHC 9.6.1 rejects previously working code

Thanks Tom and Rodrigo. That clarifies the problem. We will need to think which solution makes better sense. On Wed, 12 Apr 2023 at 15:01, Rodrigo Mesquita wrote: > Indeed, this is included in the GHC 9.6.x Migration Guide >

Re: GHC 9.6.1 rejects previously working code

Indeed, this is included in the GHC 9.6.x Migration Guide . Unfortunately, I’m also not sure there is a solution for this particular where (T m) is only a Monad if m instances MonadIO. As

Re: GHC 9.6.1 rejects previously working code

On Wed, Apr 12, 2023 at 02:32:43PM +0530, Harendra Kumar wrote: > instance MonadIO m => Monad (T m) where > return = pure > (>>=) = undefined > > instance MonadTrans T where > lift = undefined I guess it's nothing to do with 9.6 per se, but rather the difference between *

GHC 9.6.1 rejects previously working code

The following code compiles with older compilers but does not compile with GHC 9.6.1: {-# LANGUAGE KindSignatures #-} module A () where import Control.Monad.IO.Class import Control.Monad.Trans.Class data T (m :: * -> *) a = T instance Functor (T m) where fmap f T = undefined instance