Csound.Control.Evt

Documentation

data Evt a

A stream of events. We can convert a stream of events to the procedure with the function runEvt. It waits for events and invokes the given procedure when the event happens.

Constructors

Evt

Fields

runEvt :: Bam a -> SE ()

Instances

Functor Evt

Monoid (Evt a)

type Bam a = a -> SE ()

A procedure. Something that takes a value and suddenly bams with it.

Core functions

boolToEvt :: BoolSig -> Evt Unit

Converts booleans to events.

evtToBool :: Evt a -> SE BoolSig

Converts an event to boolean signal. It forgets everything about the event values. Signal equals to one when an event happens and zero otherwise.

sigToEvt :: Sig -> Evt Unit

Triggers an event when signal equals to 1.

stepper :: Tuple a => a -> Evt a -> SE a

Converts events to signals.

filterE :: (a -> BoolD) -> Evt a -> Evt a

Filters events with predicate.

filterSE :: (a -> SE BoolD) -> Evt a -> Evt a

Filters events with effectful predicate.

accumSE :: Tuple s => s -> (a -> s -> SE (b, s)) -> Evt a -> Evt b

Accumulator for events with side effects.

accumE :: Tuple s => s -> (a -> s -> (b, s)) -> Evt a -> Evt b

Accumulator for events.

filterAccumE :: Tuple s => s -> (a -> s -> (BoolD, b, s)) -> Evt a -> Evt b

Accumulator with filtering. It can skip the events from the event stream. If the third element of the triple equals to 1 then we should include the event in the resulting stream. If the element equals to 0 we skip the event.

filterAccumSE :: Tuple s => s -> (a -> s -> SE (BoolD, b, s)) -> Evt a -> Evt b

Accumulator for events with side effects and filtering. Event triggers only if the first element in the tripplet is true.

type family Snap a :: *

A snapshot of the signal. It converts a type of the signal to the type of the value in the given moment. Instances:

 type instance Snap D   = D
 type instance Snap Str = Str
 type instance Snap Tab = Tab

 type instance Snap Sig = D
 
 type instance Snap (a, b) = (Snap a, Snap b)
 type instance Snap (a, b, c) = (Snap a, Snap b, Snap c)
 type instance Snap (a, b, c, d) = (Snap a, Snap b, Snap c, Snap d)
 type instance Snap (a, b, c, d, e) = (Snap a, Snap b, Snap c, Snap d, Snap e)
 type instance Snap (a, b, c, d, e, f) = (Snap a, Snap b, Snap c, Snap d, Snap e, Snap f)

snapshot :: (Tuple a, Tuple (Snap a)) => (Snap a -> b -> c) -> a -> Evt b -> Evt c

Get values of some signal at the given events.

snaps :: Sig -> Evt D

Constructs an event stream that contains values from the given signal. Events happens only when the signal changes.

sync :: (Default a, Tuple a) => D -> Evt a -> Evt a

Executes actions synchronized with global tempo (in Hz).

 runEvtSync tempoCps evt proc

syncBpm :: (Default a, Tuple a) => D -> Evt a -> Evt a

the sync function but time is measured in beats per minute.

Opcodes

metroE :: Sig -> Evt Unit

Behaves like metro, but returns an event stream.

impulseE :: D -> Evt Unit

Fires a single event in the given time ahead.

changedE :: [Sig] -> Evt Unit

Behaves like changed, but returns an event stream.

triggerE :: Sig -> Sig -> Sig -> Evt Unit

Behaves like trigger, but returns an event stream.

loadbang :: Evt Unit

Fires a single event right now.

 loadbang = pulseE 0

impulse :: D -> Sig

Fires a single true value in the given time ahead.

Higher-level event functions

eventList :: [(D, D, a)] -> Evt [(D, D, a)]

Makes an event stream from list of events.

cycleE :: (Tuple a, Arg a) => [a] -> Evt b -> Evt a

Constructs an event stream that contains an infinite repetition values from the given list. When an event happens this function takes the next value from the list, if there is no values left it starts from the beggining of the list.

iterateE :: Tuple a => a -> (a -> a) -> Evt b -> Evt a

When something happens on the given event stream resulting event stream contains an application of some unary function to the given initial value. So the event stream contains the values:

 [s0, f s0, f (f s0), f (f (f s0)), ...]

repeatE :: Tuple a => a -> Evt b -> Evt a

Substitutes all values in the input stream with the given constant value.

appendE :: Tuple a => a -> (a -> a -> a) -> Evt a -> Evt a

Accumulates a values from the given event stream with binary function. It's a variant of the fold for event streams.

 appendE z f evt

When value a happens with evt, the resulting event stream contains a value (z f a) and in the next time z equals to this value.

mappendE :: (Monoid a, Tuple a) => Evt a -> Evt a

A special variant of the function appendE for the monoids. Initial value is mempty and binary function is mappend which belong to the instance of the class Monoid.

partitionE :: (a -> BoolD) -> Evt a -> (Evt a, Evt a)

Splits event stream on two streams with predicate.

splitToggle :: Evt D -> (Evt D, Evt D)

Splits a toggle event stream on on-events and off-events.

oneOf :: (Tuple a, Arg a) => [a] -> Evt b -> Evt a

Constructs an event stream that contains values from the given list which are taken in the random order.

freqOf :: (Tuple a, Arg a) => Rnds a -> Evt b -> Evt a

Constructs an event stream that contains values from the given list which are taken in the random order. In the list we specify not only values but the frequencies of occurrence. Sum of the frequencies should be equal to one.

freqAccum :: (Tuple s, Tuple (b, s), Arg (b, s)) => s -> (a -> s -> Rnds (b, s)) -> Evt a -> Evt b

This function combines the functions accumE and freqOf. We transform the values of the event stream with stateful function that produce not just values but the list of values with frequencies of occurrence. We apply this function to the current state and the value and then at random pick one of the values.

randDs :: Evt b -> Evt D

An event stream of the random values in the interval (0, 1).

randInts :: (D, D) -> Evt b -> Evt D

An event stream of the integers taken from the given diapason.

randSkip :: D -> Evt a -> Evt a

Skips elements at random.

 randSkip prob

where prob is probability of includinng the element in the output stream.

randSkipBy :: (a -> D) -> Evt a -> Evt a

Skips elements at random.

 randSkip probFun

It behaves just like randSkip, but probability depends on the value.

range :: (D, D) -> Evt b -> Evt D

 range (xMin, xMax) === cycleE [xMin .. pred xMax]

listAt :: (Tuple a, Arg a) => [a] -> Evt D -> Evt a

Turns an event of indices to the event of the values from the list. A value is taken with index.

every :: (Tuple a, Arg a) => Int -> [Int] -> Evt a -> Evt a

Specialization of the function masked.

 every n [a, b, c, ..] evt

constructs a mask that skips first n elements and then produces an event and skips next (a - 1) events, then produces an event and skips next (b - 1) events and so on. It's useful for construction of the percussive beats. For example

 every 0 [2] (metroE 2)

triggers an event on the odd beats. With this function we can create a complex patterns of cyclic events.

masked :: (Tuple a, Arg a) => [D] -> Evt a -> Evt a

Filters events with the mask. A mask is a list of ones and zeroes. n'th element from the given list should be included in the resulting stream if the n'th element from the list equals to one or skipped if the element equals to zero.