Generic Types

// Generic type alias
type Container<Value> = {
	value: Value
}

// Generic interface
interface Box<Contents> {
	contents: Contents
}

// Usage
const stringBox: Box<string> = { contents: 'hello' }
const numberBox: Box<number> = { contents: 42 }

// ❌ Bad: the caller picks the type, not the data
function getData<Data>(): Data {
	return fetchData() as Data
}

const user = getData<User>() // Compiles even if fetchData returns wrong shape!

1. Create a generic LoadingState<Data> discriminated union with four statuses:
   • idle — no payload
   • loading — no payload
   • success — carries data of type Data
   • error — carries an error string
2. Implement createSuccess so it returns a success state whose data is the argument you passed in
3. Implement createError so it returns an error state whose error is the message string you passed in (keep it generic over Data for typing)
4. Export createSuccess and createError by name

Completion criteria

• Named exports: createSuccess, createError
• Success results have status success and preserve the input in data
• Error results have status error and preserve the message in error
• Works with string, number, and object data via generics