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variable / @typed/fx/Fx

provideContext

Provides an already-built Effect Context to the entire Fx run.

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

Follow one execution

Use the caller-owned context without acquiring or releasing its service instances.

Fx timelineprovideContext(context)provideContext
OperatorprovideContext(context)
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.

The Context is captured when this combinator is created and reused for each subscription. Its services are available to all source Effects and removed from R. This function does not acquire or release those service values; their owner must keep them valid for every subscription that uses the result. Source completion, failure, and interruption are unchanged.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Signatures

export declare const provideContext: {
    <R2>(services: Context.Context<R2>): <A, E, R>(fx: Fx<A, E, R>) => Fx<A, E, Exclude<R, R2>>;
    <A, E, R, R2>(fx: Fx<A, E, R>, services: Context.Context<R2>): Fx<A, E, Exclude<R, R2>>;
};

Why

Callers that already own service instances should not rebuild them through a resourceful Layer merely to satisfy an Fx’s environment.

Ownership and lifetime

The Context is captured when this combinator is created and reused for each subscription. Its services are available to all source Effects and removed from R. This function does not acquire or release those service values; their owner must keep them valid for every subscription that uses the result. Source completion, failure, and interruption are unchanged.

Examples

import { Context, Effect } from "effect"
import { provideContext } from "@typed/fx/Fx"
import { fromEffect } from "@typed/fx/Fx"

class Config extends Context.Service<Config, { readonly url: string }>()("Config") {}
const context = Context.make(Config, { url: "/api" })
const runnable = provideContext(fromEffect(Effect.map(Config, (x) => x.url)), context)

Other public imports

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

Source