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variable / @typed/fx/Fx

flip

Emits typed failures as values and fails with the first successful value.

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

Follow one execution

Emits typed failures as values and fails with the first successful value.

Fx timelineflip turns typed failures into values and values into failuresflip
Operatorflip
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.

If a source Cause contains any Fail, the first typed error e is delivered as success and the entire Cause is discarded, including defects or interrupts composed beside that Fail. A Cause with no Fail propagates unchanged. A source success a terminates the returned Fx with typed failure a. The source subscription is the only lifetime and external interruption still stops it.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Signatures

export declare const flip: <A, E, R>(fx: Fx<A, E, R>) => Fx<E, A, R>;

Why

Channel inversion makes an error-producing computation composable through success operators, mirroring Effect’s flip without erasing either type.

Ownership and lifetime

If a source Cause contains any Fail, the first typed error e is delivered as success and the entire Cause is discarded, including defects or interrupts composed beside that Fail. A Cause with no Fail propagates unchanged. A source success a terminates the returned Fx with typed failure a. The source subscription is the only lifetime and external interruption still stops it.

Examples

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

const errorsAsValues = flip(fail("offline"))
The first Fail wins over the rest of a composite Cause
```ts
import { Cause } from "effect"
import { flip } from "@typed/fx/Fx"
import { failCause } from "@typed/fx/Fx"

const composite = Cause.combine(Cause.fail("offline"), Cause.die("decoder defect"))
const errorValue = flip(failCause(composite))
```

Other public imports

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

Source