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function / @typed/fx

Fx.Service

Defines an Effect service whose value is also a directly runnable Fx.

Package version
2.0.0-beta.13
Category
Providing services
Since
1.0.0
Member of
Fx

Follow one execution

Defining the service class is inert. Running it looks up the provided Fx and delegates delivery; a missing service is a defect.

Fx timelineService<Feed, Quote>()("Feed")Service
OperatorService<Feed, Quote>()("Feed")
Read this diagram

Follow each lane from left to right. Events stacked vertically share a tick; the green cursor marks the current time across every lane.

  • A value
    The text inside the pill is the emitted value.
  • Work starts
    The raised chevron starts an inner run (^ in the source).
  • The run returns
    The vertical bar ends this lane’s run.
  • A cause is delivered
    The exclamation mark belongs to this lane.
  • Work is interrupted
    The cross marks cancellation of this run.
  • Current time
    The line and diamond move together across all lanes.
  • Happening now
    A highlighted event is at the current tick.
  • Still ahead
    Muted, dashed values have not happened yet.
  • Time continues
    The lane’s arrow is not a return marker. An empty stretch can be quiet work that is still running.

Illustrated ticks start at 0. At 1×, one illustrated tick takes one second; captions specify real durations when timing matters. A cause or interruption belongs to its lane, and other work may continue. Scroll horizontally to inspect the rest of a long timeline.

Defining the class starts no work. Class.make acquires the producer when its layer is built, supplies the acquisition context to it, and binds its lifetime to the layer scope. Running the class reads the currently installed implementation.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

import { Fx } from "@typed/fx";

Access Fx.Service through the imported Fx export. Its declaration below describes the member.

This public exposure is a re-export. Its import path is supported; declaration documentation is shared with the other public exposures below.

Signatures

export declare function Service<Self, A, E = never>(): <const Id extends string>(id: Id) => Fx.Class<Self, Id, A, E>;

Why

Applications often need a producer selected by the Effect environment: a clock, event source, transport, or domain feed. Service keeps that dependency in R and provides the corresponding layer constructor without a parallel wrapper API.

Ownership and lifetime

Defining the class starts no work. Class.make acquires the producer when its layer is built, supplies the acquisition context to it, and binds its lifetime to the layer scope. Running the class reads the currently installed implementation.

Examples

import { Effect, Layer } from "effect"
import { Fx } from "@typed/fx"

class Ticks extends Fx.Service<Ticks, number>()("app/Ticks") {}

const TicksLive = Ticks.make(Fx.succeed(1))
const values = Fx.collectAll(Ticks).pipe(Effect.provide(TicksLive))
const program = Effect.map(values, (items) => items[0])

Other public imports

These import paths expose the same declaration. Each page retains its own public name and signature.

Source