Effect Module Request

Effect Module Request

Owned scope

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

What it is for

• The Request module provides a way to model requests to external data sources in a functional and composable manner. Requests represent descriptions of operations that can be batched, cached, and executed efficiently.

API quick reference

• of
• fail
• succeed
• Services
• failCause
• makeEntry
• isRequest
• Any
• Class
• Entry
• Error
• Result
• tagged
• Request
• Success
• complete
• Variance
• Constructor
• Full API list: references/​api-reference.md

How to use it

• Start with constructor-style APIs to build values/​services before composing operations.
• Use the reference docs to select the smallest API surface that solves your task.
• Validate behavior against existing tests before introducing new usage patterns.

Starter example

import type { Request } from "effect";

// Define a request that fetches a user by ID
interface GetUser extends Request.Request<string, Error> {
  readonly _tag: "GetUser";
  readonly id: number;
}

// Define a request that fetches all users
interface GetAllUsers extends Request.Request<ReadonlyArray<string>, Error> {
  readonly _tag: "GetAllUsers";
}

Common pitfalls

• 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/​Request.ts
• Representative tests: packages/​effect/​test/​Request.test.ts
• API details: references/​api-reference.md
• Usage notes: references/​usage-reference.md
• Ownership mapping: references/​owner.md