Re: [Haskell-cafe] Do I Need To Write An Instance for Assertable Here?

Here's the important info: liftMoment :: MonadMoment m => Moment a -> m a instance MonadMoment MomentIO instance MonadMoment Moment So liftMoment gives you a MomentIO or a Moment, not an IO. You need to do something with that. From https://hackage.haskell.org/package/reactive-banana-1.0.0.0/docs/Reactive-Ba... compile :: MomentIO () -> IO EventNetwork It looks like the intended usage is to compile into an EventNetwork, then use the functions that operate on EventNetwork (like "actuate" to start it). If you need to get a boolean value out, you need another way to do so (such as using reactimate to call a callback) -- ryan On Fri, Nov 13, 2015 at 8:48 AM, Michael Litchard wrote:

I think I'm on the right track. I have commented out all test harness code and have changed the signature for bufferPopulated

bufferPopulated :: UAC -> IO Bool bufferPopulated ev = do let eInput = ev <$ never eValidated = toVAC <$> eInput bBufferMap <- liftMoment ((buffer eValidated eClear) :: Moment (Behavior BufferMap)) let r2 = [(Just $ BufferMap $ M.insert (AID (Data.Text.pack "100")) (toVAC ev) (M.empty :: M.Map AID VAC))] r1 <- (interpret (eBuffer bBufferMap) []) :: IO [Maybe BufferMap]) return $ r1 == r2

I believe this should work, but here's the error

tests/Spec.hs:35:17: No instance for (MonadMoment IO) arising from a use of ‘liftMoment’ In a stmt of a 'do' block: bBufferMap <- liftMoment ((buffer eValidated eClear) :: Moment (Behavior BufferMap))

Let's take a look at MonadMoment from Reactive.Banana.Combinators class Monad m => MonadMoment m where An instance of the MonadMoment class denotes a computation that happens at one particular moment in time. Unlike the Moment monad, it need not be pure anymore. Methods liftMoment :: Moment a -> m a Instances MonadMoment MomentIO MonadMoment Moment

m can be any Monad, IO is a Monad. so liftMoment should lift the Moment Behavior (BufferMap) to IO Behavior (BufferMap) , why doesn't it. What's wrong with my reasoning?

On Fri, Nov 13, 2015 at 7:16 AM, Michael Litchard wrote:

...

Below is some test code I am writing for my game, the link to the entire codebase, the error message and some discussion

main :: IO () main = defaultMain [ testGroup "EventNetwork Input" [testBuffer "bBuffer" Populated] ]

testBuffer :: String -> BufferState -> Test testBuffer name Populated = testCase name $ assert $ bufferPopulated (UAC (PlayerCommand (Move (ToPlanetName Mongo)) (AID (Data.Text.pack "100")))) testBuffer name Empty = testCase name $ assert $ bufferEmptied (UAC (PlayerCommand (Move (ToPlanetName Mongo)) (AID (Data.Text.pack "100"))))

bufferPopulated :: UAC -> MomentIO Bool bufferPopulated ev = do let eInput = ev <$ never eValidated = toVAC <$> eInput bBufferMap <- (buffer eValidated eClear) :: MomentIO (Behavior BufferMap) let r2 = [(Just $ BufferMap $ M.insert (AID (Data.Text.pack "100")) (toVAC ev) (M.empty :: M.Map AID VAC))] r1 <- liftIO $ ((interpret (eBuffer bBufferMap) []) :: IO [Maybe BufferMap]) return $ r1 == r2

bufferEmptied :: UAC -> MomentIO Bool bufferEmptied ev = undefined

eBuffer :: Behavior BufferMap -> Event a -> Event BufferMap eBuffer bBufferMap nvr = bBufferMap <@ (() <$ nvr)

eClear = Clear <$ (() <$ never)

When I run stack build I get

tests/Spec.hs:26:19: No instance for (Test.HUnit.Base.Assertable (MomentIO Bool)) arising from a use of ‘assert’ In the expression: assert In the second argument of ‘($)’, namely ‘assert $ bufferPopulated (UAC (PlayerCommand (Move (ToPlanetName Mongo)) (AID (pack "100"))))’ In the expression: testCase name $ assert $ bufferPopulated (UAC (PlayerCommand (Move (ToPlanetName Mongo)) (AID (pack "100"))))

The problem lies with buffer. It relies on accumB which requires the MomentIO monad. I considered writing an instance for Assertable, but I think that's a red-herring and the answer lies elsewhere. I need to reconcile the fact that assert wants an IO Bool, but accumB wants a MomentIO. Maybe I do need to write an instance for Assertable.

Here's the link to the project:https://github.com/mlitchard/emporos/tree/banana-1.0.0/src

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