[Haskell-cafe] transformers problem: Could not deduce MonadTrans (StateT s) ??
miguelimo38 at yandex.ru
Sat Jun 23 19:44:43 CEST 2012
On 23 Jun 2012, at 21:27, Anton Kholomiov wrote:
> At last..
> No, it wants me to define an instance for
> (StateT s) which is supposed to be defined
> be the authors of the library.
> Actually I discovered that I have two libraries
> called transformers.
> So when I'm doing
> import Control.Monad.Trans (0.2.2.0)
Ehm... seems like you're importing mtl instead of transformers. AFAIK there is no "Control.Monad.Trans" module in transformers.
> I get the error
> And when I'm doing
> import Control.Monad.Trans.Class (0.2.2.0)
> It compiles.
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