Effect Service

Effect Service Generator

Generate Effect-TS services following project conventions.

Service Template

import * as Context from "effect/Context";
import * as Effect from "effect/Effect";
import * as Layer from "effect/Layer";

// Interface defines the contract
export interface MyServiceInterface {
  readonly doSomething: (
    input: InputType,
  ) => Effect.Effect<OutputType, MyError>;
}

// Tag for dependency injection
export class MyService extends Context.Tag("@wowlab/services/MyService")<
  MyService,
  MyServiceInterface
>() {}

// Live implementation
export const MyServiceLive: Layer.Layer<MyService, never, Dependencies> =
  Layer.effect(
    MyService,
    Effect.gen(function* () {
      const dep = yield* SomeDependency;

      return {
        doSomething: (input) =>
          Effect.gen(function* () {
            // implementation
            return result;
          }),
      } satisfies MyServiceInterface;
    }),
  );

Alternative: Effect.Service Pattern

For simpler services with built-in Default layer:

export class MyService extends Effect.Service<MyService>()("MyService", {
  dependencies: [Dep1.Default, Dep2.Default],
  effect: Effect.gen(function* () {
    const dep1 = yield* Dep1;
    const dep2 = yield* Dep2;

    return {
      doSomething: (input) => Effect.gen(function* () { ... }),
    };
  }),
}) {}

File Location

• New service: packages/wowlab-services/src/internal/{domain}/
• Re-export from: packages/wowlab-services/src/{Domain}.ts

Naming Conventions

• Interface: {Name}Interface or {Name}Service
• Tag: @wowlab/services/{Name}
• Layer: {Name}Live or {Name}.Default
• Errors: {Name}Error using Data.TaggedError

Instructions

1. Ask what the service should do
2. Identify dependencies needed
3. Generate interface with typed methods
4. Generate Layer implementation
5. Add re-export to barrel file