TypeCompose-0.0: Type composition classes & instances Source code Contents Index

Control.DataDriven Portability portable Stability experimental Maintainer conal@conal.net

Contents Plumbing for "events" and subscription Data-driven computations

Description

Data-driven computations

Synopsis

type Sink src a = a -> Updater src type Updater src = src () type News src = Sink src (Updater src) type DataDrivenG news src = Compose ((,) news) src dd :: news -> src a -> DataDrivenG news src a mapSrc :: (src a -> src b) -> DataDrivenG news src a -> DataDrivenG news src b type DataDriven src = DataDrivenG (News src) src runDD :: (Monoid (Updater src), Applicative src) => DataDriven src () -> Updater src joinDD :: Monad src => DataDriven src (src a) -> DataDriven src a

Plumbing for "events" and subscription

type Sink src a = a -> Updater src Source

Sinks (consumers) of values

type Updater src = src () Source

Updaters (actions)

type News src = Sink src (Updater src) Source

News publisher -- somewhere to register updaters to be executed when events occur.

Data-driven computations

type DataDrivenG news src = Compose ((,) news) src Source

The general type of data-driven computations. Represented as a news publisher (news) and a source of new values (src). Clients interested in the value subscribe to news and extract a new value from src when notified that the value may have changed. When news is a monoid and src is an applicative functor, DataDriven news src is an applicative functor also. The applicative property is very convenient for composition. See the more specific type DataDriven.

dd :: news -> src a -> DataDrivenG news src a Source

Construct a data-driven computation from a subscription service (Monoid) and a value source subscriber (Applicative).

mapSrc :: (src a -> src b) -> DataDrivenG news src a -> DataDrivenG news src b Source

Modify the source part of a DataDriven computation.

type DataDriven src = DataDrivenG (News src) src Source

Data driven with news publisher

runDD :: (Monoid (Updater src), Applicative src) => DataDriven src () -> Updater src Source

Run a unit-valued DataDriven computation. Causes the source to be executed and registered with the subscriber.

joinDD :: Monad src => DataDriven src (src a) -> DataDriven src a Source

Apply join to a source

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