[Haskell-cafe] Hoopl: Combining CheckingFuelMonad with State?
jgbailey at gmail.com
Mon Jun 27 19:54:28 CEST 2011
I asked this question on StackOverflow and someone suggested using
StateT. Unfortunately I don't think I can really carry around the
state I'd like to:
On Fri, Jun 24, 2011 at 5:56 PM, Antoine Latter <aslatter at gmail.com> wrote:
> 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
>> Thanks in advance for any help!
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>> Glasgow-haskell-users at haskell.org
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