effect-module-semaphore

name: effect-module-semaphore description: Guidance for effect/Semaphore focused on APIs like make, makePartitioned, and makeUnsafe. Load after effect-skill-router when this module is the primary owner.

Effect Module Semaphore

Owned scope

• Owns only effect/Semaphore.
• Source of truth: packages/effect/src/Semaphore.ts.

What it is for

• Module-specific APIs and usage patterns for Effect programs.

API quick reference

• make
• makePartitioned
• makeUnsafe
• makePartitionedUnsafe
• Semaphore
• Partitioned
• PartitionedTypeId
• Full API list: references/api-reference.md

How to use it

• Start with constructor-style APIs to build values/services before composing operations.
• Prefer pipe-based composition to keep transformations explicit and testable.
• Treat stateful APIs as synchronization boundaries and keep updates atomic.

Starter example

import { Effect, Semaphore } from "effect";

// Create and use a semaphore for controlling concurrent access
const program = Effect.gen(function* () {
  const semaphore = yield* Semaphore.make(2);

  return yield* semaphore.withPermits(1)(Effect.succeed("Resource accessed"));
});

Common pitfalls

• Unsafe APIs bypass checks; prefer safe variants unless you control invariants explicitly.
• Prefer explicit, typed combinators over ad-hoc casting or unchecked assumptions.

Not covered here

• Adjacent modules in effect/* and effect/unstable/* are out of scope for this owner.

Escalate to

• effect-skill-router for routing and ownership checks.

Reference anchors

• Module source: packages/effect/src/Semaphore.ts
• Representative tests: packages/effect/test/Semaphore.test.ts
• API details: references/api-reference.md
• Usage notes: references/usage-reference.md
• Ownership mapping: references/owner.md