So the best I could come up with is:
untilDone :: Monad m => Pipe (Either String ScoreBoard) (Either String
ScoreBoard) m ()
untilDone = do
x <- await
yield x
case x of
Right (Done _) -> return ()
_ -> untilDone
pipeScore :: (Monad m) => Pipe (Either String Int) (Either String
ScoreBoard) m ()
pipeScore = (flip S.evalStateT) emptyBoard go
where
go = do
x <- lift $ await
case x of
Left s -> lift $ yield (Left s)
Right n -> do
b <- S.get
let y = score n b
lift $ yield y
case y of
Right (Current (_, b')) -> do S.put b'; go
_ -> return ()
Then
model :: Model Board String (Either String ScoreBoard)
model = asPipe (pipeQuit >-> pipeRead >-> pipeScore >-> untilDone)
On Tuesday, May 13, 2014 12:12:21 PM UTC+2, Pierre R wrote:
>
>
>
>> pipeScore :: (Monad m) => Board -> Pipe (Either String Int) (Either
>> String ScoreBoard) m ()
>> pipeScore = evalStateT $ for untilDone $ \x -> case x of
>> Left s -> lift $ yield (Left s)
>> Right n -> do
>> let y = score n b
>> lift $ yield y
>> case y of
>> Right (Current (_, b')) -> put b'
>> _ -> return ()
>>
>>
> This does not seem to compile.
> - `for` returns a Pipe, not a StateT
> - `n` coming from `untilDone` is actually `ScoreBoard`, not an `Int`.
>
> I am still trying to figure it out alone but with no luck so far ;-)
> For instance, this one compiles but does not output anything
>
> pipeScore :: (Monad m) => Board -> Pipe (Either String Int) (Either String
> ScoreBoard) m ()
> pipeScore = S.evalStateT $ forever $ do
> x <- lift $ await
> case x of
> Left s -> lift $ yield (Left s)
> Right n -> do
> b <- S.get
> let y = score n b
> lift $ yield y
> case y of
> Right (Current (_, b')) -> S.put b'
> _ -> return ()
>
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