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variable / @typed/fx/Fx

make

Creates an Fx from a function that provides values to a Sink.

This is the lowest-level constructor for Fx, giving you full control over the stream’s behavior.

Package version
2.0.0-beta.7
Category
Callback sources
Since
1.0.0

Follow one execution

The custom run Effect calls the sink twice, awaits both deliveries, then returns. make itself imposes no cardinality policy.

Fx timelinemake(sink => deliverPair)make
Operatormake(sink => deliverPair)
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.

make only stores run; it starts no work. Every call to Fx.run executes that function in the caller’s fiber. The function must keep all acquisition and cleanup inside its returned Effect or a required Scope; its error channel is never because producer failures must be sent to sink.onFailure.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Signatures

export declare const make: <A, E = never, R = never>(run: <RSink = never>(sink: Sink<A, E, RSink>) => Effect.Effect<unknown, never, R | RSink>) => Fx<A, E, R>;

Why

make is the protocol boundary for custom producers. It exposes the real Sink operation so libraries can define cardinality, ordering, concurrency, causes, and services without an opinionated source wrapper.

Ownership and lifetime

make stores the callback without invoking it. Calling fx.run(sink) asks the callback to construct its Effect; executing that Effect performs the subscription. Keep acquisition, publication, and cleanup inside the returned Effect or a required Scope, rather than performing side effects while constructing it. The returned Effect has no typed failure channel because producer failures are delivered through sink.onFailure; defects and interruption can still affect the run.

Examples

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

const pair = make<number>((sink) =>
  Effect.andThen(sink.onSuccess(1), sink.onSuccess(2))
)
const program = collectAll(pair)

Other public imports

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

Source