Re: [Haskell-cafe] Hopefully simple monad question

O, great. I didn't know you can write it this way. Tom Nielsen wrote:

newtype VMT m a = VMT {runVMT :: StateT VMState m a} deriving (Monad, MonadIO, MonadTrans, TransM, MonadState VMState)

works here (ghc-6.10.3)

On Wed, Sep 16, 2009 at 11:42 AM, Miguel Mitrofanov wrote:

...

newtype VMT m a = VMT {runVMT :: StateT VMState m a} deriving (Monad, MonadIO, MonadTrans, TransM)

Unfortunately, you can't automatically derive MonadState, since it's a multi-paremeter type class. You'll have to write down the derivation yourself.

---

Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe