[Haskell-cafe] Hoopl: Combining CheckingFuelMonad with State?

Antoine Latter aslatter at gmail.com
Sat Jun 25 02:56:40 CEST 2011

Hi Justin, this message might be better on the haskell-cafe list (or
the excellent beginers list!).

When you tried to write the get/put implementations, what problems
were you running into?


On Sat, Jun 25, 2011 at 7:50 AM, Justin Bailey <jgbailey at gmail.com> wrote:
> I'd like to carry around some state when rewriting. It seems like
> CheckingFuelMonad, etc. are set up to use with other monads but I
> can't get the types to agree.
> Using MTL I've managed to come up with these types:
>> newtype RewriteOnce a = R (State Bool a)
>>   deriving (Monad)
>> instance MonadState s (CheckingFuelMonad RewriteOnce) where
>>   get = undefined
>>   put = undefined
> But I cannot write the definitions for get and put. Is this possible
> or am I misundersanding CheckingFuelMonad? Is there a better approach
> altogether?
> Thanks in advance for any help!
> Justin
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