effect-io-ai

Package: effect
Module: TxSubscriptionRef

TxSubscriptionRef.modify

Modifies the value of the TxSubscriptionRef using a function that returns both a result and the new value. The new value is published to all subscribers atomically.

When to use

Use to compute a separate return value and next TxSubscriptionRef state in one transactional update.

Example (Modifying and returning a value)

import { Effect, TxSubscriptionRef } from "effect"

const program = Effect.gen(function*() {
  const ref = yield* TxSubscriptionRef.make(10)
  const result = yield* TxSubscriptionRef.modify(ref, (n) => [`was ${n}`, n + 1])
  console.log(result) // "was 10"
  console.log(yield* TxSubscriptionRef.get(ref)) // 11
})

See

• update for deriving the next value without a separate return value
• set for replacing the value directly

Signature

declare const modify: { <A, B>(f: (current: A) => [returnValue: B, newValue: A]): (self: TxSubscriptionRef<A>) => Effect.Effect<B>; <A, B>(self: TxSubscriptionRef<A>, f: (current: A) => [returnValue: B, newValue: A]): Effect.Effect<B>; }

Source

Since v3.10.0