effect-io-ai

Package: effect
Module: Effect

Effect.acquireUseRelease

Runs resource acquisition, usage, and release as one bracketed effect.

When to use

Use to bracket acquire, use, and release logic in one effect.

Details

acquireUseRelease does the following:

1. Ensures that the Effect value that acquires the resource will not be interrupted. Note that acquisition may still fail due to internal reasons (such as an uncaught exception).
2. Ensures that the release Effect value will not be interrupted, and will be executed as long as the acquisition Effect value successfully acquires the resource.

During the time period between the acquisition and release of the resource, the use Effect value will be executed.

If the release Effect value fails, then the entire Effect value will fail, even if the use Effect value succeeds. If this fail-fast behavior is not desired, errors produced by the release Effect value can be caught and ignored.

Example (Acquiring resources with cleanup)

import { Console, Effect, Exit } from "effect"

interface Database {
  readonly connection: string
  readonly query: (sql: string) => Effect.Effect<string>
}

const program = Effect.acquireUseRelease(
  // Acquire - connect to database
  Effect.gen(function*() {
    yield* Console.log("Connecting to database...")
    return {
      connection: "db://localhost:5432",
      query: (sql: string) => Effect.succeed(`Result for: ${sql}`)
    }
  }),
  // Use - perform database operations
  (db) =>
    Effect.gen(function*() {
      yield* Console.log(`Connected to ${db.connection}`)
      const result = yield* db.query("SELECT * FROM users")
      yield* Console.log(`Query result: ${result}`)
      return result
    }),
  // Release - close database connection
  (db, exit) =>
    Effect.gen(function*() {
      if (Exit.isSuccess(exit)) {
        yield* Console.log(`Closing connection to ${db.connection} (success)`)
      } else {
        yield* Console.log(`Closing connection to ${db.connection} (failure)`)
      }
    })
)

Effect.runPromise(program)
// Output:
// Connecting to database...
// Connected to db://localhost:5432
// Query result: Result for: SELECT * FROM users
// Closing connection to db://localhost:5432 (success)

See

• acquireRelease for scoped resources whose use happens later

Signature

declare const acquireUseRelease: <Resource, E, R, A, E2, R2, E3, R3>(acquire: Effect<Resource, E, R>, use: (a: Resource) => Effect<A, E2, R2>, release: (a: Resource, exit: Exit.Exit<A, E2>) => Effect<void, E3, R3>) => Effect<A, E | E2 | E3, R | R2 | R3>

Source

Since v2.0.0