Monad composition

[Andre W B Furtado]

Well, it's also possible to interchange data between these two monads by:

unsafeIOToST :: IO a -> ST s a
stToIO :: ST s a -> IO a

Can anyone tell the possible problems related to
unsafeIOToST?
^^^^^^

-- Andre

----- Original Message -----
From: Tom Bevan <tom@regex.com.au>
To: Andre W B Furtado <awfurtado@uol.com.br>
Cc: Haskell Cafe List <haskell-cafe@haskell.org>
Sent: Thursday, January 24, 2002 4:13 AM
Subject: Re: Monad composition


> Andre,
>
> I can't work out how it should be done.
> The way I see it, the StateIO monad should have four functions
> associated with it.
> 1/ update - a function to update the state
> 2/ retrieve - a function to retrieve the state from the monad
> These two are inherited from the standard State monad
> 3/ input - make a character from stndIn available to the state
> transformation functions
> 4/ output - send the state of the monad after a certain set of
> transformations to stndOut
>
> I've managed to write functions 1-3 but not 4.
>
> Here's my work so far.I'm not really sure if this is on the right track.
>
> Tom
>
>
> On Thu, 2002-01-24 at 14:32, Andre W B Furtado wrote:
> > Hi, I have the same problem. Did anyone answered your question?
> >
> > Thanks,
> > -- Andre
> >
> > ----- Original Message -----
> > From: Tom Bevan <tom@regex.com.au>
> > To: Haskell Cafe List <haskell-cafe@haskell.org>
> > Sent: Wednesday, January 23, 2002 4:29 AM
> > Subject: Monad composition
> >
> >
> > >
> > > Hi all,
> > >
> > > I'm writing a programme which requires IO actions to be interleaved
with
> > > operations on a State monad. From what I can work out, this means that
> > > the IO Monad and the StateTransformation monad need to be composed
into
> > > a single highr order monad.
> > > Does anyone have any references or pointers on how this should be
done?
> > >
> > >
> > > Tom
> > >
> > >
> > >
> > > _______________________________________________
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> > > Haskell-Cafe@haskell.org
> > > http://www.haskell.org/mailman/listinfo/haskell-cafe
> > >
> >
>
>