TxRef is a transactional value, it can be read and modified within the body of a transaction.

When to use

Use to store mutable state that must be read and modified inside Effect transactions.

Details

Accessed values are tracked by the transaction in order to detect conflicts and in order to track changes, a transaction will retry whenever a conflict is detected or whenever the transaction explicitely calls to Effect.txRetry and any of the accessed TxRef values change.

Example (Using a transactional reference)

import { Effect, TxRef } from "effect"

const program = Effect.gen(function*() {
  // Create a transactional reference
  const ref: TxRef.TxRef<number> = yield* TxRef.make(0)

  // Use within a transaction
  yield* Effect.tx(Effect.gen(function*() {
    const current = yield* TxRef.get(ref)
    yield* TxRef.set(ref, current + 1)
  }))

  const final = yield* TxRef.get(ref)
  console.log(final) // 1
})