effect-dependency-injection

# Effect Dependency Injection

Master dependency injection and management in Effect applications using Context
and Layers. This skill covers service definitions, layer construction, and
composing complex dependency graphs.

## Context and Services

### Defining Services with Context.Tag

Services are defined using Context.Tag to create type-safe identifiers:

```typescript
import { Context, Effect } from "effect"

// Define service interface
interface UserService {
  getUser: (id: string) => Effect.Effect<User, UserNotFound, never>
  createUser: (data: UserData) => Effect.Effect<User, ValidationError, never>
}

// Create service tag
const UserService = Context.GenericTag<UserService>("UserService")

// Using the service
const program = Effect.gen(function* () {
  const userService = yield* UserService
  const user = yield* userService.getUser("123")
  return user
})
// Effect<User, UserNotFound, UserService>
```

### Multiple Services

```typescript
import { Context, Effect } from "effect"

interface Logger {
  info: (message: string) => Effect.Effect<void, never, never>
  error: (message: string) => Effect.Effect<void, never, never>
}

interface Database {
  query: <T>(sql: string) => Effect.Effect<T, DbError, never>
}

const Logger = Context.GenericTag<Logger>("Logger")
const Database = Context.GenericTag<Database>("Database")

// Using multiple services
const program = Effect.gen(function* () {
  const logger = yield* Logger
  const db = yield* Database

  yield* logger.info("Querying database...")
  const users = yield* db.query<User[]>("SELECT * FROM users")
  yield* logger.info(`Found ${users.length} users`)

  return users
})
// Effect<User[], DbError, Logger | Database>
```

## Creating Layers

Layers are blueprints for constructing services.

### Layer.succeed - Simple Service Implementation

```typescript
import { Context, Effect, Layer } from "effect"

interface Config {
  apiUrl: string
  timeout: number
}

const Config = Context.GenericTag<Config>("Conf