class GetUserRequest extends Record({
  userId: string
}) {}
class GetUserResponse extends Record({
  userId: string,
  userName: string
}) {}

// endpoint hosted in a Lambda Function
const endpoint = new Api.Endpoint(..);

const GameService = new Api.Service({
  serviceName: 'game-service',
});

const GetUserHandler = new Api.Call({
  endpoint,
  input: GetUserRequest,
  output: GetUserResponse
}, async request => Ok(new GetUserResponse({
  userId: request.userId,
  userName: 'user name'
})));

GameService.addOperation('GetUser', GetUserRequest,
  request => GetUserHandler.call(request));

GameService.addOperation('GetUser', GetUserRequest,
  // request.userId will synthesize a VTL transformation that extracts the userId key from the JSON payload received as a body
  request => GetUserHandler.call(request.userId));

GameService.addOperation('GetUser', GetUserRequest,
  // this time, both the input and output is transformed with VTL.
  // the output template will extract the userName field from the GetUserResponse returned by the Lambda integration
  request => GetUserHandler.call(request.userId).userName);

const queue = new SQS.Queue(..);
GameService.addOperation('SendMessage', string, s => queue.sendMessage(s));

const table = new DynamoDB.Table(..);
GameService.addOperation('PutItem', string, s => table.put(VTL.Record({
  id: s
}));

const User = GameService.addResource({
  name: 'user',
  identifiers: {
    userId: string
  }
});

User.onGet(GetUserRequest, request => GetUserHandler.call(request));