
Data.EventList.Absolute.TimeBody  Portability  Haskell 98  Stability  stable  Maintainer  haskell@henningthielemann.de 



Description 


Synopsis 

data T time body   empty :: T time body   singleton :: time > body > T time body   null :: T time body > Bool   viewL :: T time body > Maybe ((time, body), T time body)   viewR :: T time body > Maybe (T time body, (time, body))   switchL :: c > ((time, body) > T time body > c) > T time body > c   switchR :: c > (T time body > (time, body) > c) > T time body > c   cons :: time > body > T time body > T time body   snoc :: T time body > time > body > T time body   fromPairList :: [(a, b)] > T a b   toPairList :: T a b > [(a, b)]   getTimes :: T time body > [time]   getBodies :: T time body > [body]   duration :: Num time => T time body > time   mapBody :: (body0 > body1) > T time body0 > T time body1   mapTime :: (time0 > time1) > T time0 body > T time1 body   mapM :: Monad m => (time0 > m time1) > (body0 > m body1) > T time0 body0 > m (T time1 body1)   mapM_ :: Monad m => (time > m ()) > (body > m ()) > T time body > m ()   mapBodyM :: Monad m => (body0 > m body1) > T time body0 > m (T time body1)   mapTimeM :: Monad m => (time0 > m time1) > T time0 body > m (T time1 body)   merge :: (Ord time, Ord body) => T time body > T time body > T time body   mergeBy :: Ord time => (body > body > Bool) > T time body > T time body > T time body   insert :: (Ord time, Ord body) => time > body > T time body > T time body   insertBy :: Ord time => (body > body > Bool) > time > body > T time body > T time body   moveForward :: (Ord time, Num time) => T time (time, body) > T time body   decreaseStart :: (Ord time, Num time) => time > T time body > T time body   delay :: (Ord time, Num time) => time > T time body > T time body   filter :: Num time => (body > Bool) > T time body > T time body   partition :: (body > Bool) > T time body > (T time body, T time body)   slice :: Eq a => (body > a) > T time body > [(a, T time body)]   foldr :: (time > a > b) > (body > b > a) > b > T time body > b   foldrPair :: (time > body > a > a) > a > T time body > a   mapMaybe :: Num time => (body0 > Maybe body1) > T time body0 > T time body1   catMaybes :: Num time => T time (Maybe body) > T time body   normalize :: (Ord time, Num time, Ord body) => T time body > T time body   isNormalized :: (Ord time, Num time, Ord body) => T time body > Bool   collectCoincident :: Eq time => T time body > T time [body]   flatten :: (Ord time, Num time) => T time [body] > T time body   mapCoincident :: (Ord time, Num time) => ([a] > [b]) > T time a > T time b   append :: (Ord time, Num time) => T time body > T time body > T time body   concat :: (Ord time, Num time) => [T time body] > T time body   cycle :: (Ord time, Num time) => T time body > T time body   discretize :: (RealFrac time, Integral i) => T time body > T i body   resample :: (RealFrac time, Integral i) => time > T time body > T i body   checkTimes :: Ord time => T time body > T time body   collectCoincidentFoldr :: Eq time => T time body > T time [body]   collectCoincidentNonLazy :: Eq time => T time body > T time [body] 


Documentation 


Instances  




singleton :: time > body > T time body  Source 








switchL :: c > ((time, body) > T time body > c) > T time body > c  Source 


switchR :: c > (T time body > (time, body) > c) > T time body > c  Source 


cons :: time > body > T time body > T time body  Source 


snoc :: T time body > time > body > T time body  Source 


fromPairList :: [(a, b)] > T a b  Source 


toPairList :: T a b > [(a, b)]  Source 


getTimes :: T time body > [time]  Source 


getBodies :: T time body > [body]  Source 



Duration of an empty event list is considered zero.
However, I'm not sure if this is sound.


mapBody :: (body0 > body1) > T time body0 > T time body1  Source 


mapTime :: (time0 > time1) > T time0 body > T time1 body  Source 


mapM :: Monad m => (time0 > m time1) > (body0 > m body1) > T time0 body0 > m (T time1 body1)  Source 




mapBodyM :: Monad m => (body0 > m body1) > T time body0 > m (T time body1)  Source 


mapTimeM :: Monad m => (time0 > m time1) > T time0 body > m (T time1 body)  Source 


merge :: (Ord time, Ord body) => T time body > T time body > T time body  Source 

The first important function is merge
which merges the events of two lists into a new time order list.


mergeBy :: Ord time => (body > body > Bool) > T time body > T time body > T time body  Source 

Note that merge compares entire events rather than just start
times. This is to ensure that it is commutative, a desirable
condition for some of the proofs used in secref{equivalence}.
It is also necessary to assert a unique representation
of the performance independent of the structure of the 'Music.T note'.
The same function for inserting into a time ordered list with a trailing pause.
The strictness annotation is necessary for working with infinite lists.
Here are two other functions that are already known for nonpadded time lists.


insert :: (Ord time, Ord body) => time > body > T time body > T time body  Source 

The final critical function is insert,
which inserts an event
into an already timeordered sequence of events.
For instance it is used in MidiFiles to insert a NoteOff event
into a list of NoteOn and NoteOff events.


insertBy :: Ord time => (body > body > Bool) > time > body > T time body > T time body  Source 


moveForward :: (Ord time, Num time) => T time (time, body) > T time body  Source 

Move events towards the front of the event list.
You must make sure, that no event is moved before time zero.
This works only for finite lists.


decreaseStart :: (Ord time, Num time) => time > T time body > T time body  Source 


delay :: (Ord time, Num time) => time > T time body > T time body  Source 




partition :: (body > Bool) > T time body > (T time body, T time body)  Source 


slice :: Eq a => (body > a) > T time body > [(a, T time body)]  Source 

Since we need it later for MIDI generation,
we will also define a slicing into equivalence classes of events.


foldr :: (time > a > b) > (body > b > a) > b > T time body > b  Source 


foldrPair :: (time > body > a > a) > a > T time body > a  Source 


mapMaybe :: Num time => (body0 > Maybe body1) > T time body0 > T time body1  Source 





sort sorts a list of coinciding events,
that is all events but the first one have time difference 0.
normalize sorts all coinciding events in a list
thus yielding a canonical representation of a time ordered list.




collectCoincident :: Eq time => T time body > T time [body]  Source 

We will also sometimes need a function which groups events by equal start times.
This implementation is not so obvious since we work with time differences.
The criterion is: Two neighbouring events start at the same time
if the second one has zero time difference.




mapCoincident :: (Ord time, Num time) => ([a] > [b]) > T time a > T time b  Source 

Apply a function to the lists of coincident events.


append :: (Ord time, Num time) => T time body > T time body > T time body  Source 







Here are some functions for discretizing the time information.
When converting the precise relative event times
to the integer relative event times
we have to prevent accumulation of rounding errors.
We avoid this problem with a stateful conversion
which remembers each rounding error we make.
This rounding error is used to correct the next rounding.
Given the relative time and duration of a note
the function discretizeEventM creates a State
which computes the rounded relative time.
It is corrected by previous rounding errors.
The resulting event list may have differing time differences
which were equal before discretization,
but the overall timing is uniformly close to the original.




checkTimes :: Ord time => T time body > T time body  Source 

Check whether time values are in ascending order.
The list is processed lazily and
times that are smaller than there predecessors are replaced by undefined.
If you would remove the undefined times from the resulting list
the times may still not be ordered.
E.g. consider the time list [0,3,1,2]


collectCoincidentFoldr :: Eq time => T time body > T time [body]  Source 


collectCoincidentNonLazy :: Eq time => T time body > T time [body]  Source 

Will fail on infinite lists.


Produced by Haddock version 2.4.2 