[Haskell-cafe] Newtype deriving with functional dependencies

Daniel Gorín dgorin at dc.uba.ar
Sun Feb 1 22:59:11 EST 2009

On Feb 2, 2009, at 1:06 AM, Louis Wasserman wrote:

> Is there any sensible way to make
> newtype FooT m e = FooT (StateT Bar m e) deriving (MonadState)
> work to give instance MonadState Bar (FooT m e)?
> That is, I'm asking if there would be a semantically sensible way of  
> modifying GeneralizedNewtypeDeriving to handle multi-parameter type  
> classes when there is a functional dependency involved, assuming by  
> default that the newtype is the more general of the types, perhaps?
> Louis Wasserman
> wasserman.louis at gmail.com
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe

did you try this?

newtype FooT m e = FooT (StateT Bar m e) deriving (Monad, MonadState  
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