effect-io-ai

Package: effect
Module: Ref

Ref.updateSomeAndGet

Updates the value of the Ref atomically using the given partial function and returns the current value.

When to use

Use to apply a conditional Ref update and return the resulting current value.

Details

If the partial function returns Option.some, the Ref is updated with the new value. If it returns Option.none, the Ref is left unchanged. The effect returns the current value of the Ref after the potential update.

Example (Conditionally updating and returning the current value)

import { Effect, Option, Ref } from "effect"

const program = Effect.gen(function*() {
  const counter = yield* Ref.make(10)

  // Only update if value is greater than 5
  const result1 = yield* Ref.updateSomeAndGet(
    counter,
    (n) => n > 5 ? Option.some(n / 2) : Option.none()
  )
  console.log(result1) // 5 (updated and returned)

  // Try to update again with same condition
  const result2 = yield* Ref.updateSomeAndGet(
    counter,
    (n) => n > 5 ? Option.some(n / 2) : Option.none()
  )
  console.log(result2) // 5 (unchanged because 5 is not > 5)
})

See

• updateSome for conditional updates without returning a value
• updateAndGet for always updating and returning the new value

Signature

declare const updateSomeAndGet: (<A>(pf: (a: A) => Option.Option<A>) => (self: Ref<A>) => Effect.Effect<A>) & (<A>(self: Ref<A>, pf: (a: A) => Option.Option<A>) => Effect.Effect<A>)

Source

Since v2.0.0