[Haskell-cafe] Fighting the monad stack, MonadIO

Luke Palmer lrpalmer at gmail.com
Thu Apr 10 15:42:35 EDT 2008

On Thu, Apr 10, 2008 at 2:50 PM, Adam Smyczek <adam.smyczek at gmail.com> wrote:
> For a small webapi binding I try to implement a session like monad
>  by building a stack including BrowserAction from Network.Browser
>  module as following:
>  newtype RBAction a = RBAction
>     { exec :: ErrorT String (StateT RBState BrowserAction) a }
>     deriving (Functor, Monad, MonadState RBState)
>  I would like the RBAction to implement MonadIO as well,
>  but fight with the liftIO function for hours now, without success.
>  Any idea how the implementation of liftIO could look like?

I suspect BrowserAction does not implement MonadIO (lest you could
just put MonadIO in the deriving clause).  So, that depends on how
BrowserAction is implemented.  What package is Network.Browser in?


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