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
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