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variable / @typed/fx/RefSubject

getOrElse

Returns a Computed that yields the value inside the Option, or the fallback when None. Works with Computed<Option<A>> (e.g. from fromOption / fromNullable) and with Filtered<A>.

Package version
2.0.0-beta.7
Category
Optional queries
Since
1.0.0

Import

import { getOrElse } from "@typed/fx/RefSubject";

Signatures

export declare const getOrElse: {
    <A>(fallback: () => A): <E, R>(ref: Computed<Option.Option<A>, E, R> | Filtered<A, E, R>) => Computed<A, E, R>;
    <A, E, R>(ref: Computed<Option.Option<A>, E, R> | Filtered<A, E, R>, fallback: () => A): Computed<A, E, R>;
};

Why

Returns a Computed that yields the value inside the Option, or the fallback when None. Works with Computed<Option<A>> (e.g. from fromOption / fromNullable) and with Filtered<A>. Current reads and pushed versions use the same derivation, preventing snapshot and subscription behavior from diverging.

Ownership and lifetime

The returned Computed never fails for absence: None or an absent Filtered value invokes fallback. It preserves only the input’s declared E and R; the pure fallback adds no failure, service, subscription, or retained value.

Examples

import { Effect, Option } from "effect"
import * as RefSubject from "@typed/fx/RefSubject"

const program = Effect.gen(function* () {
  const ref = yield* RefSubject.fromOption(Option.some(42))
  const withDefault = RefSubject.getOrElse(ref, () => 0)
  expect(yield* withDefault).toBe(42)

  const empty = yield* RefSubject.fromNullable(null)
  const fallback = RefSubject.getOrElse(empty, () => 99)
  expect(yield* fallback).toBe(99)
})

Other public imports

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

Source