SharedSource

Shared sources, for the Streams an Environment hands out: each hot and counted, so however many subscribe, one underlying source runs, started by the first subscriber and stopped when the last one leaves. byTarget keeps one per target, one observer on each element, and make one for the whole Environment. An Environment builds its sources with these, as @wardic/dom does.

import * as SharedSource from "@wardic/core/SharedSource"

const resize = yield* SharedSource.byTarget((target) => Effect.succeed(resizesOf(target)))
// Both share one observer on `card`:
Stream.runForEach(resize(card), onLayout)
Stream.runForEach(resize(card), onScroll)

Interfaces

Options

byTarget's and make's options.

Properties

idleTimeToLive?

readonly idleTimeToLive?: Input;

How long a source with no subscriber left keeps running before it stops, so a quick re-subscribe reuses it. Default: none, stopped at once.

Variables

byTarget

const byTarget: <A>(lookup, options?) => Effect.Effect<(target) => Stream.Stream<A>, never, Scope.Scope>;

A shared source per target: a function from a target to a Stream that's hot and counted for that target. The first subscriber for a target starts lookup(target)'s source, later ones share it, and it stops when the last one for that target leaves, after idleTimeToLive if it's given.

Type Parameters

A

A

Parameters

lookup

(target) => Effect.Effect<Stream.Stream<A>, never, Scope.Scope>

options?

Options

Returns

Effect.Effect<(target) => Stream.Stream<A>, never, Scope.Scope>

Example

// `resizesOf(target)`: an Environment's own Stream of a target's sizes
const resize = yield* SharedSource.byTarget((target) => Effect.succeed(resizesOf(target)))

make

const make: <A>(acquire, options?) => Effect.Effect<Stream.Stream<A>, never, Scope.Scope>;

One shared source for the whole Environment: a Stream that's hot and counted. The first subscriber starts acquire's source, later ones share it, and it stops when the last one leaves, after idleTimeToLive if it's given. byTarget's form without a target.

// `viewportChanges`: an Environment's own Stream of its viewport's size
const viewport = yield* SharedSource.make(Effect.succeed(viewportChanges))
Stream.runForEach(viewport, onResize) // one listener, however many subscribe