{-# LANGUAGE Arrows #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE TypeFamilies #-}

{- |
Utilities to create 'ClSF's.
The fundamental effect that 'ClSF's have is
reading the time information of the clock.
It can be used for many purposes, for example digital signal processing.
-}
module FRP.Rhine.ClSF.Util where

-- base
import Control.Arrow
import Control.Category (Category)
import qualified Control.Category (id)
import Data.Maybe (fromJust)
import Data.Monoid (Last (Last), getLast)

-- containers
import Data.Sequence

-- transformers
import Control.Monad.Trans.Reader (ask, asks)

-- dunai
import Control.Monad.Trans.MSF.Reader (readerS)
import Data.MonadicStreamFunction.Instances.VectorSpace ()

-- simple-affine-space
import Data.VectorSpace

-- rhine
import FRP.Rhine.ClSF.Core
import FRP.Rhine.ClSF.Except
import FRP.Rhine.Clock

-- * Read time information

-- | Read the environment variable, i.e. the 'TimeInfo'.
timeInfo :: Monad m => ClSF m cl a (TimeInfo cl)
timeInfo :: forall (m :: Type -> Type) cl a.
Monad m =>
ClSF m cl a (TimeInfo cl)
timeInfo = forall (m :: Type -> Type) b a. Monad m => m b -> MSF m a b
constM forall (m :: Type -> Type) r. Monad m => ReaderT r m r
ask

{- | Utility to apply functions to the current 'TimeInfo',
such as record selectors:
@
printAbsoluteTime :: ClSF IO cl () ()
printAbsoluteTime = timeInfoOf absolute >>> arrMCl print
@
-}
timeInfoOf :: Monad m => (TimeInfo cl -> b) -> ClSF m cl a b
timeInfoOf :: forall (m :: Type -> Type) cl b a.
Monad m =>
(TimeInfo cl -> b) -> ClSF m cl a b
timeInfoOf TimeInfo cl -> b
f = forall (m :: Type -> Type) b a. Monad m => m b -> MSF m a b
constM forall a b. (a -> b) -> a -> b
$ forall (m :: Type -> Type) r a.
Monad m =>
(r -> a) -> ReaderT r m a
asks TimeInfo cl -> b
f

-- | Continuously return the time difference since the last tick.
sinceLastS :: Monad m => ClSF m cl a (Diff (Time cl))
sinceLastS :: forall (m :: Type -> Type) cl a.
Monad m =>
ClSF m cl a (Diff (Time cl))
sinceLastS = forall (m :: Type -> Type) cl b a.
Monad m =>
(TimeInfo cl -> b) -> ClSF m cl a b
timeInfoOf forall cl. TimeInfo cl -> Diff (Time cl)
sinceLast

-- | Continuously return the time difference since clock initialisation.
sinceInitS :: Monad m => ClSF m cl a (Diff (Time cl))
sinceInitS :: forall (m :: Type -> Type) cl a.
Monad m =>
ClSF m cl a (Diff (Time cl))
sinceInitS = forall (m :: Type -> Type) cl b a.
Monad m =>
(TimeInfo cl -> b) -> ClSF m cl a b
timeInfoOf forall cl. TimeInfo cl -> Diff (Time cl)
sinceInit

-- | Continuously return the absolute time.
absoluteS :: Monad m => ClSF m cl a (Time cl)
absoluteS :: forall (m :: Type -> Type) cl a. Monad m => ClSF m cl a (Time cl)
absoluteS = forall (m :: Type -> Type) cl b a.
Monad m =>
(TimeInfo cl -> b) -> ClSF m cl a b
timeInfoOf forall cl. TimeInfo cl -> Time cl
absolute

-- | Continuously return the tag of the current tick.
tagS :: Monad m => ClSF m cl a (Tag cl)
tagS :: forall (m :: Type -> Type) cl a. Monad m => ClSF m cl a (Tag cl)
tagS = forall (m :: Type -> Type) cl b a.
Monad m =>
(TimeInfo cl -> b) -> ClSF m cl a b
timeInfoOf forall cl. TimeInfo cl -> Tag cl
tag

{- |
Calculate the time passed since this 'ClSF' was instantiated.
This is _not_ the same as 'sinceInitS',
which measures the time since clock initialisation.

For example, the following gives a sawtooth signal:

@
sawtooth = safely $ do
  try $ sinceStart >>> proc time -> do
    throwOn () -< time > 1
    returnA    -< time
  safe sawtooth
@

If you replace 'sinceStart' by 'sinceInitS',
it will usually hang after one second,
since it doesn't reset after restarting the sawtooth.
-}
sinceStart :: (Monad m, TimeDomain time) => BehaviourF m time a (Diff time)
sinceStart :: forall (m :: Type -> Type) time a.
(Monad m, TimeDomain time) =>
BehaviourF m time a (Diff time)
sinceStart =
  forall (m :: Type -> Type) cl a. Monad m => ClSF m cl a (Time cl)
absoluteS forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> proc time
time -> do
    time
startTime <- forall (m :: Type -> Type) cl a. Monad m => ClSF m cl a a
keepFirst -< time
time
    forall (a :: Type -> Type -> Type) b. Arrow a => a b b
returnA -< time
time forall time. TimeDomain time => time -> time -> Diff time
`diffTime` time
startTime

-- * Useful aliases

-- TODO Is it cleverer to generalise to Arrow?

{- | Alias for 'Control.Category.>>>' (sequential composition)
with higher operator precedence, designed to work with the other operators, e.g.:

> clsf1 >-> clsf2 @@ clA ||@ sched @|| clsf3 >-> clsf4 @@ clB

The type signature specialises e.g. to

> (>->) :: Monad m => ClSF m cl a b -> ClSF m cl b c -> ClSF m cl a c
-}
infixr 6 >->

(>->) ::
  Category cat =>
  cat a b ->
  cat b c ->
  cat a c
>-> :: forall (cat :: Type -> Type -> Type) a b c.
Category cat =>
cat a b -> cat b c -> cat a c
(>->) = forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
(>>>)

-- | Alias for 'Control.Category.<<<'.
infixl 6 <-<

(<-<) ::
  Category cat =>
  cat b c ->
  cat a b ->
  cat a c
<-< :: forall (cat :: Type -> Type -> Type) b c a.
Category cat =>
cat b c -> cat a b -> cat a c
(<-<) = forall {k} (cat :: k -> k -> Type) (b :: k) (c :: k) (a :: k).
Category cat =>
cat b c -> cat a b -> cat a c
(<<<)

{- | Output a constant value.
Specialises e.g. to this type signature:

> arr_ :: Monad m => b -> ClSF m cl a b
-}
arr_ :: Arrow a => b -> a c b
arr_ :: forall (a :: Type -> Type -> Type) b c. Arrow a => b -> a c b
arr_ = forall (a :: Type -> Type -> Type) b c.
Arrow a =>
(b -> c) -> a b c
arr forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. a -> b -> a
const

-- | The identity synchronous stream function.
clId :: Monad m => ClSF m cl a a
clId :: forall (m :: Type -> Type) cl a. Monad m => ClSF m cl a a
clId = forall {k} (cat :: k -> k -> Type) (a :: k).
Category cat =>
cat a a
Control.Category.id

-- * Basic signal processing components

-- ** Integration and differentiation

{- | The output of @integralFrom v0@ is the numerical Euler integral
   of the input, with initial offset @v0@.
-}
integralFrom ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  v ->
  BehaviorF m td v v
integralFrom :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td v v
integralFrom v
v0 = proc v
v -> do
  s
_sinceLast <- forall (m :: Type -> Type) cl b a.
Monad m =>
(TimeInfo cl -> b) -> ClSF m cl a b
timeInfoOf forall cl. TimeInfo cl -> Diff (Time cl)
sinceLast -< ()
  forall v s (m :: Type -> Type).
(VectorSpace v s, Monad m) =>
v -> MSF m v v
sumFrom v
v0 -< s
_sinceLast forall v a. VectorSpace v a => a -> v -> v
*^ v
v

-- | Euler integration, with zero initial offset.
integral ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  BehaviorF m td v v
integral :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
BehaviorF m td v v
integral = forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td v v
integralFrom forall v a. VectorSpace v a => v
zeroVector

{- | The output of @derivativeFrom v0@ is the numerical derivative of the input,
   with a Newton difference quotient.
   The input is initialised with @v0@.
-}
derivativeFrom ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  v ->
  BehaviorF m td v v
derivativeFrom :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td v v
derivativeFrom v
v0 = proc v
v -> do
  v
vLast <- forall (m :: Type -> Type) a. Monad m => a -> MSF m a a
iPre v
v0 -< v
v
  TimeInfo {Diff (Time cl)
Time cl
Tag cl
tag :: Tag cl
absolute :: Time cl
sinceInit :: Diff (Time cl)
sinceLast :: Diff (Time cl)
tag :: forall cl. TimeInfo cl -> Tag cl
absolute :: forall cl. TimeInfo cl -> Time cl
sinceInit :: forall cl. TimeInfo cl -> Diff (Time cl)
sinceLast :: forall cl. TimeInfo cl -> Diff (Time cl)
..} <- forall (m :: Type -> Type) cl a.
Monad m =>
ClSF m cl a (TimeInfo cl)
timeInfo -< ()
  forall (a :: Type -> Type -> Type) b. Arrow a => a b b
returnA -< (v
v forall v a. VectorSpace v a => v -> v -> v
^-^ v
vLast) forall v a. VectorSpace v a => v -> a -> v
^/ Diff (Time cl)
sinceLast

-- | Numerical derivative with input initialised to zero.
derivative ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  BehaviorF m td v v
derivative :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
BehaviorF m td v v
derivative = forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td v v
derivativeFrom forall v a. VectorSpace v a => v
zeroVector

{- | Like 'derivativeFrom', but uses three samples to compute the derivative.
   Consequently, it is delayed by one sample.
-}
threePointDerivativeFrom ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  -- | The initial position
  v ->
  BehaviorF m td v v
threePointDerivativeFrom :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td v v
threePointDerivativeFrom v
v0 = proc v
v -> do
  v
dv <- forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td v v
derivativeFrom v
v0 -< v
v
  v
dv' <- forall (m :: Type -> Type) a. Monad m => a -> MSF m a a
iPre forall v a. VectorSpace v a => v
zeroVector -< v
dv
  forall (a :: Type -> Type -> Type) b. Arrow a => a b b
returnA -< (v
dv forall v a. VectorSpace v a => v -> v -> v
^+^ v
dv') forall v a. VectorSpace v a => v -> a -> v
^/ s
2

{- | Like 'threePointDerivativeFrom',
   but with the initial position initialised to 'zeroVector'.
-}
threePointDerivative ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  BehaviorF m td v v
threePointDerivative :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
BehaviorF m td v v
threePointDerivative = forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td v v
threePointDerivativeFrom forall v a. VectorSpace v a => v
zeroVector

-- ** Averaging and filters

{- | A weighted moving average signal function.
   The output is the average of the first input,
   weighted by the second input
   (which is assumed to be always between 0 and 1).
   The weight is applied to the average of the last tick,
   so a weight of 1 simply repeats the past value unchanged,
   whereas a weight of 0 outputs the current value.
-}
weightedAverageFrom ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  -- | The initial position
  v ->
  BehaviorF m td (v, s) v
weightedAverageFrom :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td (v, s) v
weightedAverageFrom v
v0 = forall (m :: Type -> Type) c a b.
Monad m =>
c -> MSF m (a, c) (b, c) -> MSF m a b
feedback v
v0 forall a b. (a -> b) -> a -> b
$ proc ((v
v, s
weight), v
vAvg) -> do
  let
    vAvg' :: v
vAvg' = s
weight forall v a. VectorSpace v a => a -> v -> v
*^ v
vAvg forall v a. VectorSpace v a => v -> v -> v
^+^ (s
1 forall a. Num a => a -> a -> a
- s
weight) forall v a. VectorSpace v a => a -> v -> v
*^ v
v
  forall (a :: Type -> Type -> Type) b. Arrow a => a b b
returnA -< (v
vAvg', v
vAvg')

{- | An exponential moving average, or low pass.
   It will average out, or filter,
   all features below a given time constant @t@.
   (Equivalently, it filters out frequencies above @1 / (2 * pi * t)@.)
-}
averageFrom ::
  ( Monad m
  , VectorSpace v s
  , Floating s
  , s ~ Diff td
  ) =>
  -- | The initial position
  v ->
  -- | The time scale on which the signal is averaged
  Diff td ->
  BehaviorF m td v v
averageFrom :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
v -> Diff td -> BehaviorF m td v v
averageFrom v
v0 Diff td
t = proc v
v -> do
  TimeInfo {Diff (Time cl)
Time cl
Tag cl
tag :: Tag cl
absolute :: Time cl
sinceInit :: Diff (Time cl)
sinceLast :: Diff (Time cl)
tag :: forall cl. TimeInfo cl -> Tag cl
absolute :: forall cl. TimeInfo cl -> Time cl
sinceInit :: forall cl. TimeInfo cl -> Diff (Time cl)
sinceLast :: forall cl. TimeInfo cl -> Diff (Time cl)
..} <- forall (m :: Type -> Type) cl a.
Monad m =>
ClSF m cl a (TimeInfo cl)
timeInfo -< ()
  let
    weight :: s
weight = forall a. Floating a => a -> a
exp forall a b. (a -> b) -> a -> b
$ -(Diff (Time cl)
sinceLast forall a. Fractional a => a -> a -> a
/ Diff td
t)
  forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td (v, s) v
weightedAverageFrom v
v0 -< (v
v, s
weight)

-- | An average, or low pass, initialised to zero.
average ::
  ( Monad m
  , VectorSpace v s
  , Floating s
  , s ~ Diff td
  ) =>
  -- | The time scale on which the signal is averaged
  Diff td ->
  BehaviourF m td v v
average :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
average = forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
v -> Diff td -> BehaviorF m td v v
averageFrom forall v a. VectorSpace v a => v
zeroVector

{- | A linearised version of 'averageFrom'.
   It is more efficient, but only accurate
   if the supplied time scale is much bigger
   than the average time difference between two ticks.
-}
averageLinFrom ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  -- | The initial position
  v ->
  -- | The time scale on which the signal is averaged
  Diff td ->
  BehaviourF m td v v
averageLinFrom :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> Diff td -> BehaviourF m td v v
averageLinFrom v
v0 Diff td
t = proc v
v -> do
  TimeInfo {Diff (Time cl)
Time cl
Tag cl
tag :: Tag cl
absolute :: Time cl
sinceInit :: Diff (Time cl)
sinceLast :: Diff (Time cl)
tag :: forall cl. TimeInfo cl -> Tag cl
absolute :: forall cl. TimeInfo cl -> Time cl
sinceInit :: forall cl. TimeInfo cl -> Diff (Time cl)
sinceLast :: forall cl. TimeInfo cl -> Diff (Time cl)
..} <- forall (m :: Type -> Type) cl a.
Monad m =>
ClSF m cl a (TimeInfo cl)
timeInfo -< ()
  let
    weight :: s
weight = Diff td
t forall a. Fractional a => a -> a -> a
/ (Diff (Time cl)
sinceLast forall a. Num a => a -> a -> a
+ Diff td
t)
  forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> BehaviorF m td (v, s) v
weightedAverageFrom v
v0 -< (v
v, s
weight)

-- | Linearised version of 'average'.
averageLin ::
  ( Monad m
  , VectorSpace v s
  , s ~ Diff td
  ) =>
  -- | The time scale on which the signal is averaged
  Diff td ->
  BehaviourF m td v v
averageLin :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
averageLin = forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, s ~ Diff td) =>
v -> Diff td -> BehaviourF m td v v
averageLinFrom forall v a. VectorSpace v a => v
zeroVector

-- *** First-order filters

-- | Alias for 'average'.
lowPass ::
  ( Monad m
  , VectorSpace v s
  , Floating s
  , s ~ Diff td
  ) =>
  Diff td ->
  BehaviourF m td v v
lowPass :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
lowPass = forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
average

-- | Filters out frequencies below @1 / (2 * pi * t)@.
highPass ::
  ( Monad m
  , VectorSpace v s
  , Floating s
  , s ~ Diff td
  ) =>
  -- | The time constant @t@
  Diff td ->
  BehaviourF m td v v
highPass :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
highPass Diff td
t = forall (m :: Type -> Type) cl a. Monad m => ClSF m cl a a
clId forall v a. VectorSpace v a => v -> v -> v
^-^ forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
lowPass Diff td
t

-- | Filters out frequencies other than @1 / (2 * pi * t)@.
bandPass ::
  ( Monad m
  , VectorSpace v s
  , Floating s
  , s ~ Diff td
  ) =>
  -- | The time constant @t@
  Diff td ->
  BehaviourF m td v v
bandPass :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
bandPass Diff td
t = forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
lowPass Diff td
t forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
highPass Diff td
t

-- | Filters out the frequency @1 / (2 * pi * t)@.
bandStop ::
  ( Monad m
  , VectorSpace v s
  , Floating s
  , s ~ Diff td
  ) =>
  -- | The time constant @t@
  Diff td ->
  BehaviourF m td v v
bandStop :: forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
bandStop Diff td
t = forall (m :: Type -> Type) cl a. Monad m => ClSF m cl a a
clId forall v a. VectorSpace v a => v -> v -> v
^-^ forall (m :: Type -> Type) v s td.
(Monad m, VectorSpace v s, Floating s, s ~ Diff td) =>
Diff td -> BehaviourF m td v v
bandPass Diff td
t

-- * Delays

-- | Remembers and indefinitely outputs ("holds") the first input value.
keepFirst :: Monad m => ClSF m cl a a
keepFirst :: forall (m :: Type -> Type) cl a. Monad m => ClSF m cl a a
keepFirst = forall (m :: Type -> Type) a b.
Monad m =>
MSFExcept m a b Void -> MSF m a b
safely forall a b. (a -> b) -> a -> b
$ do
  a
a <- forall (m :: Type -> Type) e cl a b.
Monad m =>
ClSF (ExceptT e m) cl a b -> ClSFExcept m cl a b e
try forall (m :: Type -> Type) e cl a.
Monad m =>
ClSF (ExceptT e m) cl e a
throwS
  forall (m :: Type -> Type) a b e.
Monad m =>
MSF m a b -> MSFExcept m a b e
safe forall a b. (a -> b) -> a -> b
$ forall (a :: Type -> Type -> Type) b c.
Arrow a =>
(b -> c) -> a b c
arr forall a b. (a -> b) -> a -> b
$ forall a b. a -> b -> a
const a
a

{- | Remembers all input values that arrived within a given time window.
   New values are appended left.
-}
historySince ::
  (Monad m, Ord (Diff (Time cl)), TimeDomain (Time cl)) =>
  -- | The size of the time window
  Diff (Time cl) ->
  ClSF m cl a (Seq (TimeInfo cl, a))
historySince :: forall (m :: Type -> Type) cl a.
(Monad m, Ord (Diff (Time cl)), TimeDomain (Time cl)) =>
Diff (Time cl) -> ClSF m cl a (Seq (TimeInfo cl, a))
historySince Diff (Time cl)
dTime = forall (m :: Type -> Type) r a b.
Monad m =>
MSF m (r, a) b -> MSF (ReaderT r m) a b
readerS forall a b. (a -> b) -> a -> b
$ forall (m :: Type -> Type) a s.
Monad m =>
(a -> s -> s) -> s -> MSF m a s
accumulateWith (TimeInfo cl, a) -> Seq (TimeInfo cl, a) -> Seq (TimeInfo cl, a)
appendValue forall a. Seq a
empty
  where
    appendValue :: (TimeInfo cl, a) -> Seq (TimeInfo cl, a) -> Seq (TimeInfo cl, a)
appendValue (TimeInfo cl
ti, a
a) Seq (TimeInfo cl, a)
tias = forall a. (a -> Bool) -> Seq a -> Seq a
takeWhileL (TimeInfo cl -> (TimeInfo cl, a) -> Bool
recentlySince TimeInfo cl
ti) forall a b. (a -> b) -> a -> b
$ (TimeInfo cl
ti, a
a) forall a. a -> Seq a -> Seq a
<| Seq (TimeInfo cl, a)
tias
    recentlySince :: TimeInfo cl -> (TimeInfo cl, a) -> Bool
recentlySince TimeInfo cl
ti (TimeInfo cl
ti', a
_) = forall time. TimeDomain time => time -> time -> Diff time
diffTime (forall cl. TimeInfo cl -> Time cl
absolute TimeInfo cl
ti) (forall cl. TimeInfo cl -> Time cl
absolute TimeInfo cl
ti') forall a. Ord a => a -> a -> Bool
< Diff (Time cl)
dTime

{- | Delay a signal by certain time span,
   initialising with the first input.
-}
delayBy ::
  (Monad m, Ord (Diff td), TimeDomain td) =>
  -- | The time span to delay the signal
  Diff td ->
  BehaviorF m td a a
delayBy :: forall (m :: Type -> Type) td a.
(Monad m, Ord (Diff td), TimeDomain td) =>
Diff td -> BehaviorF m td a a
delayBy Diff td
dTime = forall (m :: Type -> Type) cl a.
(Monad m, Ord (Diff (Time cl)), TimeDomain (Time cl)) =>
Diff (Time cl) -> ClSF m cl a (Seq (TimeInfo cl, a))
historySince Diff td
dTime forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall (a :: Type -> Type -> Type) b c.
Arrow a =>
(b -> c) -> a b c
arr (forall a. Seq a -> ViewR a
viewr forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall {a}. ViewR a -> Maybe a
safeHead) forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall (m :: Type -> Type) a. Monad m => a -> MSF m (Maybe a) a
lastS forall a. HasCallStack => a
undefined forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall (a :: Type -> Type -> Type) b c.
Arrow a =>
(b -> c) -> a b c
arr forall a b. (a, b) -> b
snd
  where
    safeHead :: ViewR a -> Maybe a
safeHead ViewR a
EmptyR = forall a. Maybe a
Nothing
    safeHead (Seq a
_ :> a
a) = forall a. a -> Maybe a
Just a
a

-- * Timers

{- | Throws an exception after the specified time difference,
   outputting the time passed since the 'timer' was instantiated.
-}
timer ::
  ( Monad m
  , TimeDomain td
  , Ord (Diff td)
  ) =>
  Diff td ->
  BehaviorF (ExceptT () m) td a (Diff td)
timer :: forall (m :: Type -> Type) td a.
(Monad m, TimeDomain td, Ord (Diff td)) =>
Diff td -> BehaviorF (ExceptT () m) td a (Diff td)
timer Diff td
diff = proc a
_ -> do
  Diff td
time <- forall (m :: Type -> Type) time a.
(Monad m, TimeDomain time) =>
BehaviourF m time a (Diff time)
sinceStart -< ()
  ()
_ <- forall (m :: Type -> Type) e cl.
Monad m =>
e -> ClSF (ExceptT e m) cl Bool ()
throwOn () -< Diff td
time forall a. Ord a => a -> a -> Bool
> Diff td
diff
  forall (a :: Type -> Type -> Type) b. Arrow a => a b b
returnA -< Diff td
time

-- | Like 'timer_', but doesn't output the remaining time at all.
timer_ ::
  ( Monad m
  , TimeDomain td
  , Ord (Diff td)
  ) =>
  Diff td ->
  BehaviorF (ExceptT () m) td a ()
timer_ :: forall (m :: Type -> Type) td a.
(Monad m, TimeDomain td, Ord (Diff td)) =>
Diff td -> BehaviorF (ExceptT () m) td a ()
timer_ Diff td
diff = forall (m :: Type -> Type) td a.
(Monad m, TimeDomain td, Ord (Diff td)) =>
Diff td -> BehaviorF (ExceptT () m) td a (Diff td)
timer Diff td
diff forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall (a :: Type -> Type -> Type) b c.
Arrow a =>
(b -> c) -> a b c
arr (forall a b. a -> b -> a
const ())

-- | Like 'timer', but divides the remaining time by the total time.
scaledTimer ::
  ( Monad m
  , TimeDomain td
  , Fractional (Diff td)
  , Ord (Diff td)
  ) =>
  Diff td ->
  BehaviorF (ExceptT () m) td a (Diff td)
scaledTimer :: forall (m :: Type -> Type) td a.
(Monad m, TimeDomain td, Fractional (Diff td), Ord (Diff td)) =>
Diff td -> BehaviorF (ExceptT () m) td a (Diff td)
scaledTimer Diff td
diff = forall (m :: Type -> Type) td a.
(Monad m, TimeDomain td, Ord (Diff td)) =>
Diff td -> BehaviorF (ExceptT () m) td a (Diff td)
timer Diff td
diff forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall (a :: Type -> Type -> Type) b c.
Arrow a =>
(b -> c) -> a b c
arr (forall a. Fractional a => a -> a -> a
/ Diff td
diff)

-- * To be ported to Dunai

{- | Remembers the last 'Just' value,
   defaulting to the given initialisation value.
-}
lastS :: Monad m => a -> MSF m (Maybe a) a
lastS :: forall (m :: Type -> Type) a. Monad m => a -> MSF m (Maybe a) a
lastS a
a = forall (a :: Type -> Type -> Type) b c.
Arrow a =>
(b -> c) -> a b c
arr forall a. Maybe a -> Last a
Last forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall n (m :: Type -> Type). (Monoid n, Monad m) => n -> MSF m n n
mappendFrom (forall a. Maybe a -> Last a
Last (forall a. a -> Maybe a
Just a
a)) forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall (a :: Type -> Type -> Type) b c.
Arrow a =>
(b -> c) -> a b c
arr (forall a. Last a -> Maybe a
getLast forall {k} (cat :: k -> k -> Type) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall a. HasCallStack => Maybe a -> a
fromJust)