purescript-halogen-subscriptions

Utilities for creating and managing push-based subscriptions, inspired by the event library. This library is used to implement subscriptions in Halogen, but it can be used independently of Halogen.

Install halogen-subscriptions with Spago:

spago install halogen-subscriptions

The halogen-subscriptions library helps you create and transform push-based subscriptions. Most subscriptions follow this pattern:

1. Use the create function to produce a paired Emitter and Listener. An emitter is a possibly-infinite list of values that you can subscribe to, and a listener is a mechanism for pushing values to the emitter.
2. Use the subscribe function to subscribe to outputs from the emitter by providing a callback function to run each time a value is emitted.
3. Use the notify function to push values to the emitter via the listener.
4. Use the unsubscribe function to end a subscription to an emitter.

Here's a simple example that logs "Hello" and then "Goodbye":

module Main where import Prelude import Effect (Effect) import Effect.Console as Console import Halogen.Subscription as HS main :: Effect Unit main = do { emitter, listener } <- HS.create subscription <- HS.subscribe emitter \str -> Console.log str HS.notify listener "Hello" HS.notify listener "Goodbye!" HS.unsubscribe subscription

Emitters can be combined and transformed to make more sophisticated subscriptions.

Module documentation is published on Pursuit.