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 <cgaebel@uwaterloo.ca> wrote:
> 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

>
> Regards,
>   - Clark
>
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--
Ivan Lazar Miljenovic
Ivan.Miljenovic@gmail.com
http://IvanMiljenovic.wordpress.com