effect-io-ai

Package: effect
Module: Ref

Ref.getAndSet

Gets the current value of the Ref, sets it to the specified value, and returns the previous value atomically.

When to use

Use to replace a plain Ref value while returning the previous value.

Example (Replacing a value atomically)

import { Effect, Ref } from "effect"

const program = Effect.gen(function*() {
  const ref = yield* Ref.make("initial")

  // Get current value and set new value atomically
  const previous = yield* Ref.getAndSet(ref, "updated")
  console.log(previous) // "initial"

  const current = yield* Ref.get(ref)
  console.log(current) // "updated"
})

See

• set for setting without returning the previous value
• getAndUpdate for deriving the new value from the previous value

Signature

declare const getAndSet: (<A>(value: A) => (self: Ref<A>) => Effect.Effect<A>) & (<A>(self: Ref<A>, value: A) => Effect.Effect<A>)

Source

Since v2.0.0