effect-io-ai

Package: effect
Module: SubscriptionRef

SubscriptionRef.modifySome

Computes a return value and optionally updates the reference.

When to use

Use to return a separate result while synchronously deciding whether to publish a new SubscriptionRef value.

Details

If the function returns Option.some for the new value, the value is set and published. If it returns Option.none, the reference is left unchanged and no update is published.

Example (Conditionally modifying a value)

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

const program = Effect.gen(function*() {
  const ref = yield* SubscriptionRef.make(10)

  const result = yield* SubscriptionRef.modifySome(
    ref,
    (n) =>
      n > 5 ? ["Updated", Option.some(n * 2)] : ["Not updated", Option.none()]
  )
  console.log(result)

  const newValue = yield* SubscriptionRef.get(ref)
  console.log("New value:", newValue)
})

Signature

declare const modifySome: { <B, A>(modify: (a: A) => readonly [B, Option.Option<A>]): (self: SubscriptionRef<A>) => Effect.Effect<B>; <A, B>(self: SubscriptionRef<A>, modify: (a: A) => readonly [B, Option.Option<A>]): Effect.Effect<B>; }

Source

Since v2.0.0