Re: [Haskell-cafe] primitive operations in StateT

The monad my code is currently written in is: type MC = MCT Identity -- where MCT is the monad transformer version of it. I have two options for threading state through this: MCT (ST s) a StateT s MC a The first option would work if I had some function with the signature MCT Identity a -> MCT (ST s) a but I know of no such function, and the second one would work if I had some way of making StateT a member of PrimMonad. Can I see an example with 'lift'? - Clark On Tuesday, April 16, 2013, Ivan Lazar Miljenovic wrote:

On 16 April 2013 15:04, Clark Gaebel javascript:;> wrote:

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Hi list!

I want to use MVectors in a StateT monad transformer.

How do I do that? StateT isn't a member of 'PrimMonad', and I have no idea how to make it one.

You can use Control.Monad.Trans.lift to lift the PrimMonad operations to PrimMonad m => StateT s m

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Regards, - Clark

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