FRP.Event.Class

class (Alternative event, Filterable event) <= IsEvent event  where

Functions which an Event type should implement, so that Behaviors can be defined in terms of any such event type:

• fold: combines incoming values using the specified function, starting with the specific initial value.
• keepLatest flattens a nested event, reporting values only from the most recent inner event.
• sampleOn: samples an event at the times when a second event fires.
• fix: compute a fixed point, by feeding output events back in as inputs.

Members

• fold :: forall b a. (a -> b -> b) -> event a -> b -> event b
• keepLatest :: forall a. event (event a) -> event a
• sampleOn :: forall b a. event a -> event (a -> b) -> event b
• fix :: forall o i. (event i -> { input :: event i, output :: event o }) -> event o

count :: forall a event. IsEvent event => event a -> event Int

Count the number of events received.

folded :: forall a event. IsEvent event => Monoid a => event a -> event a

Combine subsequent events using a Monoid.

withLast :: forall a event. IsEvent event => event a -> event { last :: Maybe a, now :: a }

Compute differences between successive event values.

mapAccum :: forall c b a event. IsEvent event => (a -> b -> Tuple b c) -> event a -> b -> event c

Map over an event with an accumulator.

For example, to keep the index of the current event:

mapAccum (\x i -> Tuple (i + 1) (Tuple x i)) 0`.

sampleOn_ :: forall b a event. IsEvent event => event a -> event b -> event a

Create an Event which samples the latest values from the first event at the times when the second event fires, ignoring the values produced by the second event.

class (Functor f) <= Filterable f  where

Filterable represents data structures which can be partitioned/filtered.

• partitionMap - partition a data structure based on an either predicate.
• partition - partition a data structure based on boolean predicate.
• filterMap - map over a data structure and filter based on a maybe.
• filter - filter a data structure based on a boolean.

Laws:

• map f ≡ filterMap (Just <<< f)
• filter ≡ filterMap <<< maybeBool
• filterMap p ≡ filter (isJust <<< p)

Default implementations are provided by the following functions:

• partitionDefault
• partitionDefaultFilter
• partitionDefaultFilterMap
• filterDefault
• filterDefaultPartition
• filterDefaultPartitionMap

Members

• filterMap :: forall b a. (a -> Maybe b) -> f a -> f b

Instances

• Filterable Array
• Filterable Maybe
• (Monoid m) => Filterable (Either m)
• Filterable List
• (Ord k) => Filterable (Map k)