532 lines
18 KiB
Haskell
532 lines
18 KiB
Haskell
module AFRPSpec (spec) where
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import Control.Arrow (arr)
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import Control.Category ((>>>))
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import Control.Monad.Fix (MonadFix (..))
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import Data.Foldable (for_)
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import AFRP
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import Data.Functor.Identity (Identity (..))
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import Data.List (sort)
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import Data.Time (NominalDiffTime, UTCTime (..), addUTCTime, diffUTCTime)
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import Data.UUID (nil)
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import Hedgehog
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import qualified Hedgehog.Gen as Gen
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import qualified Hedgehog.Range as Range
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import Test.Hspec
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import Test.Hspec.Hedgehog
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fakeRequest :: Request
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fakeRequest = Request (sec 0) nil
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sec :: Integer -> UTCTime
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sec n = UTCTime (toEnum 0) (fromIntegral n)
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runPure :: Mealy Identity a b -> [a] -> [b]
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runPure _ [] = []
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runPure m (a : as) = case runIdentity (AFRP.runMealy m id fakeRequest a) of
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(b, m') -> b : runPure m' as
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-- | Run a Mealy with a per-step wall clock (seconds since the day-0 epoch).
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runTimed :: Mealy Identity a b -> [(Integer, a)] -> [b]
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runTimed _ [] = []
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runTimed m ((s, a) : as) =
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case runIdentity (AFRP.runMealy m id (Request (sec s) nil) a) of
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(b, m') -> b : runTimed m' as
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-- | A minimal State monad for observing effectful arrows (e.g. whenA gating).
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newtype St a = St { unSt :: Int -> (a, Int) }
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instance Functor St where
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fmap f (St g) = St $ \s -> let (a, s') = g s in (f a, s')
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instance Applicative St where
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pure a = St (\s -> (a, s))
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St f <*> St x = St $ \s -> let (f', s') = f s; (a, s'') = x s' in (f' a, s'')
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instance Monad St where
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St m >>= k = St $ \s -> let (a, s') = m s; (b, s'') = unSt (k a) s' in (b, s'')
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instance MonadFix St where
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mfix f = St $ \s -> let (a, s') = unSt (f a) s in (a, s')
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runStEff :: Mealy St a b -> Int -> [a] -> ([b], Int)
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runStEff m s0 as = go m s0 as
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where
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go _ s [] = ([], s)
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go m' s (a : rest) =
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case unSt (AFRP.runMealy m' id fakeRequest a) s of
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((b, m''), s') -> let (bs, s'') = go m'' s' rest in (b : bs, s'')
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spec :: Spec
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spec = describe "AFRP" $ do
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holdSpec
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eventsSpec
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isEventSpec
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tagSpec
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toEventSpec
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lMergeSpec
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changesSpec
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edgeSpec
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filterASpec
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slidingSpec
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mapAccumSpec
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preMapAccumSpec
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durationSpec
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delayEventSpec
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debounceSpec
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rollupSpec
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fixedSpec
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effSpec
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switchSpec
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mapAccumRequestSpec
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preMapAccumRequestSpec
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whenASpec
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thenASpec
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sampleSpec
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holdSpec :: Spec
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holdSpec = describe "hold" $ do
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it "holds initial value until an Event arrives" $
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runPure (hold 'a') [Tick, Event 'b', Tick, Event 'c']
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`shouldBe` ['a', 'b', 'b', 'c']
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it "never changes on Tick" $
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runPure (hold (0 :: Int)) (replicate 5 Tick) `shouldBe` replicate 5 (0 :: Int)
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eventsSpec :: Spec
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eventsSpec = describe "events" $ do
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it "converts Tick to Left () and Event a to Right a" $
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runPure events [Tick, Event 'a', Tick, Event 'b']
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`shouldBe` [Left (), Right 'a', Left (), Right 'b']
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isEventSpec :: Spec
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isEventSpec = describe "isEvent" $ do
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it "returns False for Tick" $
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isEvent Tick `shouldBe` False
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it "returns True for Event x" $
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isEvent (Event ()) `shouldBe` True
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tagSpec :: Spec
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tagSpec = describe "tag" $ do
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it "replaces value preserving structure" $ do
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tag 'b' Tick `shouldBe` Tick
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tag 'b' (Event 'a') `shouldBe` Event 'b'
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toEventSpec :: Spec
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toEventSpec = describe "toEvent" $ do
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it "round-trips through events" $
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runPure toEvent [Left (), Right 'a', Left ()]
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`shouldBe` [Tick, Event 'a', Tick]
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it "is inverse of events modulo Event/Either" $
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runPure (events >>> toEvent) [Tick, Event 'a', Event 'b']
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`shouldBe` [Tick, Event 'a', Event 'b']
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lMergeSpec :: Spec
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lMergeSpec = describe "lMerge" $ do
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it "both Tick gives Tick" $
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lMerge (Tick :: Event Int) (Tick :: Event Int) `shouldBe` Tick
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it "prefers left Event" $
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lMerge (Event (1 :: Int)) (Event (2 :: Int)) `shouldBe` Event (1 :: Int)
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it "prefers right Event if left is Tick" $
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lMerge Tick (Event (2 :: Int)) `shouldBe` Event (2 :: Int)
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changesSpec :: Spec
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changesSpec = describe "changes" $ do
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it "first output is always Tick" $
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runPure changes "hello" !! 0 `shouldBe` Tick
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it "outputs Event only on value change" $
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runPure changes "aaaabbbcca"
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`shouldBe` [Tick, Tick, Tick, Tick
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, Event 'b', Tick, Tick
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, Event 'c', Tick
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, Event 'a'
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]
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it "first output is Tick, subsequent outputs are Event iff value changed" $
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hedgehog $ do
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xs <- forAll $ Gen.list (Range.linear 0 100) Gen.alpha
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let out = runPure changes xs
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length out === length xs
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case out of
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[] -> pure ()
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(Tick : rest) -> do
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let triples = zip3 xs (drop 1 xs) rest
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for_ triples $ \(prev, curr, o) ->
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if prev /= curr
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then o === Event curr
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else o === Tick
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_ -> failure
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edgeSpec :: Spec
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edgeSpec = describe "edge" $ do
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it "emits Event () only on rising edge" $
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runPure edge [False, True, True, False, True]
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`shouldBe` [Tick, Event (), Tick, Tick, Event ()]
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it "starts from False, so first True is a rising edge" $
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runPure edge [True, False, True]
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`shouldBe` [Event (), Tick, Event ()]
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it "Event () only on False -> True transition" $
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hedgehog $ do
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bs <- forAll $ Gen.list (Range.linear 0 50) Gen.bool
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let out = runPure edge bs
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length out === length bs
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case (bs, out) of
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([], []) -> pure ()
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(b : _, o : _) -> do
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if b then o === Event () else o === Tick
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let triples = zip3 bs (drop 1 bs) (drop 1 out)
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for_ triples $ \(prev, curr, o') ->
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if not prev && curr
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then o' === Event ()
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else o' === Tick
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_ -> failure
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filterASpec :: Spec
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filterASpec = describe "filterA" $ do
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it "lets through values matching predicate" $
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runPure (filterA (even @Int)) [1, 2, 3, 4]
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`shouldBe` [Left (), Right 2, Left (), Right 4]
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it "output is Right a iff predicate holds" $
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hedgehog $ do
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threshold <- forAll $ Gen.int (Range.linear (-10) 10)
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let p = (> threshold)
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xs <- forAll $ Gen.list (Range.linear 0 50) (Gen.int (Range.linear (-20) 20))
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let out = runPure (filterA p) xs
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length out === length xs
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for_ (zip xs out) $ \(x, o) ->
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if p x
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then o === Right x
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else o === Left ()
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slidingSpec :: Spec
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slidingSpec = describe "sliding" $ do
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it "accumulates events up to the window size" $
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runPure (sliding (3 :: Int)) [Event (1 :: Int), Event 2, Event 3, Event 4]
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`shouldBe` [[1], [1, 2], [1, 2, 3], [2, 3, 4]]
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it "Ticks don't change the accumulator" $
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runPure (sliding 2) [Event (1 :: Int), Tick, Event 2]
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`shouldBe` [[1], [1], [1, 2]]
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it "empty list stays empty" $
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runPure (sliding (5 :: Int)) ([] :: [Event Int]) `shouldBe` []
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it "output length never exceeds window size" $
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hedgehog $ do
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n <- forAll $ Gen.int (Range.constant 1 10)
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evs <- forAll $ Gen.list (Range.linear 0 20) (Gen.frequency
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[(3, Event <$> Gen.alpha), (1, pure Tick)])
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let out = runPure (sliding n) evs
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for_ out $ \xs -> assert (length xs <= n)
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mapAccumSpec :: Spec
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mapAccumSpec = describe "mapAccum" $ do
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it "running sum" $
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runPure (mapAccum (+) (0 :: Int) id) [1, 2, 3]
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`shouldBe` [1, 3, 6]
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it "post-state extraction: output uses state after applying f" $
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runPure (mapAccum (\s x -> s ++ [x]) ([] :: [Int]) id) [1, 2, 3]
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`shouldBe` [[1], [1, 2], [1, 2, 3]]
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it "output equals running sum of all inputs so far" $
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hedgehog $ do
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xs <- forAll $ Gen.list (Range.linear 0 50) (Gen.int (Range.linear (-100) 100))
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let out = runPure (mapAccum (+) (0 :: Int) id) xs
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length out === length xs
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for_ (zip3 [0 ..] xs out) $ \(i, _x, cur) ->
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cur === sum (take (i + 1) xs)
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preMapAccumSpec :: Spec
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preMapAccumSpec = describe "preMapAccum" $ do
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it "running sum with pre-state extraction" $
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runPure (preMapAccum (+) (0 :: Int) id) [1, 2, 3]
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`shouldBe` [0, 1, 3]
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it "pre-state extraction: output uses state before applying f" $
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runPure (preMapAccum (\s x -> s ++ [x]) ([] :: [Int]) id) [1, 2, 3]
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`shouldBe` [[], [1], [1, 2]]
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it "output equals running sum before current input" $
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hedgehog $ do
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xs <- forAll $ Gen.list (Range.linear 0 50) (Gen.int (Range.linear (-100) 100))
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let out = runPure (preMapAccum (+) (0 :: Int) id) xs
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length out === length xs
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for_ (zip3 [0 ..] xs out) $ \(i, _x, cur) ->
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cur === sum (take i xs)
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durationSpec :: Spec
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durationSpec = describe "duration" $ do
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it "first sample is 0, then elapsed time since first sample" $
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runTimed duration [(0, 'a'), (5, 'b'), (10, 'c')]
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`shouldBe` [0, 5, 10]
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it "measures from the first observation, not the most recent" $
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runTimed duration [(2, 'a'), (3, 'b'), (7, 'c')]
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`shouldBe` [0, 1, 5]
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it "output i equals times[i] - times[0]" $
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hedgehog $ do
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secs <- forAll $ Gen.list (Range.linear 0 50) (Gen.int (Range.linear 0 1000))
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let out = runTimed duration [(fromIntegral s, ()) | s <- secs]
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length out === length secs
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case secs of
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[] -> pure ()
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(t0 : _) -> for_ (zip secs out) $ \(s, d) ->
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d === fromIntegral (s - t0)
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delayEventSpec :: Spec
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delayEventSpec = describe "delayEvent" $ do
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let delay = 5 :: NominalDiffTime
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it "emits a queued event once the delay has elapsed" $
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runTimed (delayEvent delay)
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[(0, Event 'a'), (3, Tick), (6, Tick)]
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`shouldBe` [Tick, Tick, Event 'a']
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it "preserves order when multiple events are queued" $
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runTimed (delayEvent delay)
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[(0, Event 'a'), (1, Event 'b'), (10, Tick), (12, Tick)]
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`shouldBe` [Tick, Tick, Event 'a', Event 'b']
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it "emits nothing on pure Tick input" $
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runTimed (delayEvent delay) [(0, Tick :: Event Char), (10, Tick)]
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`shouldBe` [Tick, Tick]
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it "emits exactly one output Event per input Event" $
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hedgehog $ do
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evs <- forAll $ Gen.list (Range.linear 0 30) eventGen
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let evs' = evs ++ replicate 3 Tick
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n = length [() | Event _ <- evs]
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out = runTimed (delayEvent (1 :: NominalDiffTime))
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(zip [0, 2 ..] evs')
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length [() | Event _ <- out] === n
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debounceSpec :: Spec
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debounceSpec = describe "debounce" $ do
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let delay = 5 :: NominalDiffTime
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it "fires the last event after the quiet period" $
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runTimed (debounce delay)
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[(0, Event 'a'), (3, Tick), (6, Tick)]
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`shouldBe` [Tick, Tick, Event 'a']
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it "a newer event before firing resets the timer" $
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runTimed (debounce delay)
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[(0, Event 'a'), (3, Event 'b'), (6, Tick), (8, Tick)]
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`shouldBe` [Tick, Tick, Tick, Event 'b']
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it "collapses a burst into a single emission" $
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runTimed (debounce delay)
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[(0, Event 'a'), (1, Event 'b'), (2, Event 'c'), (10, Tick)]
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`shouldBe` [Tick, Tick, Tick, Event 'c']
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it "emits no more output Events than input Events" $
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hedgehog $ do
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evs <- forAll $ Gen.list (Range.linear 0 30) eventGen
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let nIn = length [() | Event _ <- evs]
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out = runTimed (debounce (1 :: NominalDiffTime))
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(zip [0, 2 ..] evs)
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nOut = length [() | Event _ <- out]
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assert (nOut <= nIn)
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rollupSpec :: Spec
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rollupSpec = describe "rollup" $ do
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it "passes the first `limit` events through immediately, then bursts" $
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runTimed (rollup 2 10)
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[ (0, Event 'a'), (1, Event 'b')
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, (2, Event 'c'), (3, Event 'd')
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, (12, Tick)
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]
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`shouldBe` [ Event ['a'], Event ['b']
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, Tick, Tick
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, Event ['c', 'd']
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]
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it "flushes the accumulator when the window ends on a Tick" $
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runTimed (rollup 1 10)
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[(0, Event 'a'), (1, Event 'b'), (2, Tick), (12, Tick)]
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`shouldBe` [Event ['a'], Tick, Tick, Event ['b']]
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it "is idle (Tick) until the first Event" $
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runTimed (rollup 2 10) [(0, Tick :: Event Char), (1, Tick)]
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`shouldBe` [Tick, Tick]
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it "every input Event appears exactly once across the outputs" $
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hedgehog $ do
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limit <- forAll $ Gen.int (Range.constant 1 5)
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evs <- forAll $ Gen.list (Range.linear 0 30) eventGen
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let evs' = evs ++ replicate 10 Tick
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times = [0 ..]
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out = runTimed (rollup limit 5) (zip times evs')
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emitted = concat [xs | Event xs <- out]
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sort emitted === sort [x | Event x <- evs]
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fixedSpec :: Spec
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fixedSpec = describe "fixed" $ do
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it "accumulates events within a window and rolls over on expiry" $
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runTimed (fixed 10)
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[ (0, Event 'a'), (1, Event 'b'), (2, Tick)
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, (12, Event 'c'), (13, Tick)
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]
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`shouldBe` [ ['a'], ['a', 'b'], ['a', 'b']
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, ['c'], ['c']
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]
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it "starts a window even on a leading Tick" $
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runTimed (fixed 10)
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[ (0, Tick), (1, Event 'a')
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, (12, Tick), (13, Tick)
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, (25, Event 'b')
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]
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`shouldBe` [ [], ['a'], [], [], ['b'] ]
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it "output is always the current window's accumulated list" $
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hedgehog $ do
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w <- forAll $ Gen.int (Range.constant 1 10)
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evs <- forAll $ Gen.list (Range.linear 0 30) eventGen
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let out = runTimed (fixed w) (zip [0 ..] evs)
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expected =
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[ [ x | Event x <- take (i - lo + 1) (drop lo evs) ]
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| i <- [0 .. length evs - 1]
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, let lo = (i `div` w) * w
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]
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out === expected
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eventGen :: Gen (Event Char)
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eventGen = Gen.frequency
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[ (3, Event <$> Gen.alpha)
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, (1, pure Tick)
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]
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effSpec :: Spec
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effSpec = describe "eff" $ do
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it "lifts a pure effect function into a stateless Mealy" $
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runPure (eff (\_ x -> Identity (x + 1))) [1, 2, 3]
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`shouldBe` [2, 3, 4]
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it "output equals f(input) for every step" $
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hedgehog $ do
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xs <- forAll $ Gen.list (Range.linear 0 50) (Gen.int (Range.linear (-100) 100))
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let out = runPure (eff (\_ x -> Identity (x * 2))) xs
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out === map (* 2) xs
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switchSpec :: Spec
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switchSpec = describe "switch" $ do
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it "switches to the continuation at the first Event" $
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runPure (switch (arr (\x -> (x, if x >= 3 then Event () else Tick)))
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(const (arr (const 99))))
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[1, 2, 3, 4, 5]
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`shouldBe` [1, 2, 99, 99, 99]
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it "never switches if no Event is emitted" $
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runPure (switch (arr (\x -> (x, Tick :: Event ())))
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(const (arr (const 99))))
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[1, 2, 3]
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`shouldBe` [1, 2, 3]
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it "prefix outputs come from the first arrow, suffix from the continuation" $
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hedgehog $ do
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threshold <- forAll $ Gen.int (Range.linear (-20) 20)
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xs <- forAll $ Gen.list (Range.linear 0 30) (Gen.int (Range.linear (-20) 20))
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let first = arr (\x -> (x, if x >= threshold then Event () else Tick))
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out = runPure (switch first (const (arr (const 99)))) xs
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(pre, _post) = break (>= threshold) xs
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take (length pre) out === pre
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drop (length pre) out === replicate (length xs - length pre) 99
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mapAccumRequestSpec :: Spec
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mapAccumRequestSpec = describe "mapAccumRequest" $ do
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it "accumulates request times, post-state extraction" $
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runTimed (mapAccumRequest (\req s _ -> s ++ [requestTime req]) [] id)
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[(0, 'a'), (5, 'b'), (10, 'c')]
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`shouldBe` [ [sec 0], [sec 0, sec 5], [sec 0, sec 5, sec 10] ]
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it "output i is every request time seen so far" $
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hedgehog $ do
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secs' <- forAll $ Gen.list (Range.linear 0 30) (Gen.int (Range.linear 0 100))
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let out = runTimed (mapAccumRequest (\req s _ -> s ++ [requestTime req]) [] id)
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[(fromIntegral s, ()) | s <- secs']
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|
expected = [ map (sec . fromIntegral) (take (i + 1) secs') | i <- [0 .. length secs' - 1] ]
|
|
out === expected
|
|
|
|
preMapAccumRequestSpec :: Spec
|
|
preMapAccumRequestSpec = describe "preMapAccumRequest" $ do
|
|
it "accumulates request times, pre-state extraction" $
|
|
runTimed (preMapAccumRequest (\req s _ -> s ++ [requestTime req]) [] id)
|
|
[(0, 'a'), (5, 'b'), (10, 'c')]
|
|
`shouldBe` [ [], [sec 0], [sec 0, sec 5] ]
|
|
|
|
it "output i is every request time before the current step" $
|
|
hedgehog $ do
|
|
secs' <- forAll $ Gen.list (Range.linear 0 30) (Gen.int (Range.linear 0 100))
|
|
let out = runTimed (preMapAccumRequest (\req s _ -> s ++ [requestTime req]) [] id)
|
|
[(fromIntegral s, ()) | s <- secs']
|
|
expected = [ map (sec . fromIntegral) (take i secs') | i <- [0 .. length secs' - 1] ]
|
|
out === expected
|
|
|
|
whenASpec :: Spec
|
|
whenASpec = describe "whenA" $ do
|
|
let counter = eff (\_ (_ :: Int) -> St (\s -> ((), s + 1)))
|
|
|
|
it "output is always () regardless of the predicate" $
|
|
fst (runStEff (whenA (> 5) counter) 0 [1, 6, 2, 7])
|
|
`shouldBe` [(), (), (), ()]
|
|
|
|
it "runs the inner arrow only when the predicate holds" $
|
|
snd (runStEff (whenA (> 5) counter) 0 [1, 6, 2, 7])
|
|
`shouldBe` 2
|
|
|
|
it "never runs the inner arrow when the predicate is always false" $
|
|
snd (runStEff (whenA (const False) counter) 0 [1, 6, 2, 7])
|
|
`shouldBe` 0
|
|
|
|
it "runs the inner arrow on every input when the predicate is always true" $
|
|
snd (runStEff (whenA (const True) counter) 0 [1, 6, 2, 7])
|
|
`shouldBe` 4
|
|
|
|
thenASpec :: Spec
|
|
thenASpec = describe "thenA" $ do
|
|
it "short-circuits on Left and continues on Right" $
|
|
runPure (filterA (even @Int) `thenA` filterA (> 3)) [1..6]
|
|
`shouldBe` [Left (), Left (), Left (), Right 4, Left (), Right 6]
|
|
|
|
it "(>>|) is an infix alias for thenA" $
|
|
runPure (filterA (even @Int) >>| filterA (> 3)) [1..6]
|
|
`shouldBe` [Left (), Left (), Left (), Right 4, Left (), Right 6]
|
|
|
|
it "second stage runs only when the first produces Right" $
|
|
hedgehog $ do
|
|
xs <- forAll $ Gen.list (Range.linear 0 30) (Gen.int (Range.linear (-20) 20))
|
|
let out = runPure (filterA (even @Int) >>| filterA (> 0)) xs
|
|
expected =
|
|
[ if not (even x) then Left ()
|
|
else if x > 0 then Right x
|
|
else Left ()
|
|
| x <- xs ]
|
|
out === expected
|
|
|
|
sampleSpec :: Spec
|
|
sampleSpec = describe "sample" $ do
|
|
it "tags the current value onto the Event structure" $
|
|
runPure sample [(1, Tick), (2, Event 'a'), (3, Tick)]
|
|
`shouldBe` [Tick, Event 2, Tick]
|
|
|
|
it "output is Event a iff the input event is present" $
|
|
hedgehog $ do
|
|
vals <- forAll $ Gen.list (Range.linear 0 30) (Gen.int (Range.linear 0 100))
|
|
evs <- forAll $ Gen.list (Range.linear 0 30) eventGen
|
|
let n = min (length vals) (length evs)
|
|
ps = zip (take n vals) (take n evs)
|
|
out = runPure sample ps
|
|
for_ (zip ps out) $ \((v, ev), o) ->
|
|
o === tag v ev
|