effect-io-ai

Package: effect
Module: Effect

Effect.tx

Defines a transaction boundary. Transactions are “all or nothing” with respect to changes made to transactional values (i.e. TxRef) that occur within the transaction body.

Details

If called inside an active transaction, tx composes with the current transaction and reuses its journal and retry state instead of creating a nested boundary.

Effect transactions are optimistic with retry. A transaction is retried when its body explicitly calls Effect.txRetry and any accessed transactional value changes, or when any accessed transactional value changes because a different transaction commits before the current one.

The outermost tx call creates the transaction boundary and commits or rolls back the full composed transaction.

Example (Running a transaction)

import { Effect, TxRef } from "effect"

const program = Effect.gen(function*() {
  const ref1 = yield* TxRef.make(0)
  const ref2 = yield* TxRef.make(0)

  // Nested tx calls compose into the same transaction
  yield* Effect.tx(Effect.gen(function*() {
    yield* TxRef.set(ref1, 10)
    yield* Effect.tx(TxRef.set(ref2, 20))
    const sum = (yield* TxRef.get(ref1)) + (yield* TxRef.get(ref2))
    console.log(`Transaction sum: ${sum}`)
  }))

  console.log(`Final ref1: ${yield* TxRef.get(ref1)}`) // 10
  console.log(`Final ref2: ${yield* TxRef.get(ref2)}`) // 20
})

Signature

declare const tx: <A, E, R>(effect: Effect<A, E, R>) => Effect<A, E, Exclude<R, Transaction>>

Source

Since v4.0.0