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variable / @typed/fx

Fx.result

Materializes success and failure of an Fx as Result values.

  • Success: each emitted value is wrapped as Result.succeed(value).
  • Failure: any failure (including typed error, defect, and interrupt) is materialized as Result.fail(cause). The output error type is Cause<E>, so defects and interrupts are explicitly represented in the Result and the resulting Fx has error type never.

The resulting Fx never fails at the stream level; all outcomes are emitted as Result<A, Cause<E>>. Consumers can use Result.match or Result.isSuccess / Result.isFailure to handle success vs failure (including defect/interrupt).

Package version
2.0.0-beta.13
Category
Errors and recovery
Since
1.0.0
Member of
Fx

Follow one execution

Materializes success and failure of an Fx as Result values. - Success: each emitted value is wrapped as Result.succeed(value). - Failure: any failure (including typed error, defect, and interrupt) is materialized as Result.fail(cause). The output error type is Cause<E>, so defects and interrupts are explicitly represented in the Result and the resulting Fx has error type never. The resulting Fx never fails at the stream level; all outcomes are emitted as Result<A, Cause<E>>. Consumers can use Result.match or Result.isSuccess / Result.isFailure to handle success vs failure (including defect/interrupt).

Fx timelineresult materializes values and the terminal Cause without failingresult
Operatorresult
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.

Each source value emits one successful Result in order. A terminal cause emits one failed Result and ends normally. The source is subscribed once; no resource is acquired and an interrupt reported by the source becomes data, although interrupting the outer running fiber still stops the run.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.result 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 const result: <A, E, R>(fx: Fx<A, E, R>) => Fx<Result.Result<A, Cause.Cause<E>>, never, R>;

Why

Result is convenient when success and failure should travel through one data channel, while retaining the complete Cause rather than flattening it into the typed error alone.

Ownership and lifetime

Each source value emits one successful Result in order. A terminal cause emits one failed Result and ends normally. The source is subscribed once; no resource is acquired and an interrupt reported by the source becomes data, although interrupting the outer running fiber still stops the run.

Examples

import { result } from "@typed/fx/Fx"
import { fail } from "@typed/fx/Fx"

const outcomes = result(fail("offline"))

Other public imports

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

Source