msinton / jurassic-park-service

Jurassic Park Service

Simulating a microservice oriented Jurassic Park Service!

The attractions have been implemented as individual services which we provide the clients for.

Motivations

• Use library cats to learn some simple functionality for writing lovely scala
• in particular: asLeft, asRight, some, none, leftMap and as
• practice for comprehension if desired
• try scala 2.13 pipe and tap perhaps?
• extension exercises for Monad Transformers and State Monad

Requirements

• Create a service that accepts a visitorId: String and calls to 3 attractions:

  • TRexClient.visit: Unit, but must throw an exception when visitor dies
  • TriceratopsClient.visit: Option[Error]
  • VelociraptorsClient.visit: Either[Error, Souvenir]

• Error is one of Injured, LostLimb or Dead(cause: String)

• Make up your own souvenirs!

• After a successful visit to the T-Rex our jurassic service provides the visitor with a T-Shirt (which is a Souvenir)

• When visitor has an accident (Error) no more attractions should be visited

• Our service defines visitAttractions(visitorId: String): Either[Error, List[Souvenir]]

Hints

• You can use Random.nextInt(n) to simulate getting a random service response
• import cats._, cats.implicits._

Extension

• Add an AuditService that is called to log at each client on a successful visit
• A specific log when the visitor dies
• A specific log when the visitor has an accident but has not died

Ideas for learning more

1. AuditService returns IO[Unit] - try with and without Monad Transformers
2. Use State monad for Random and Audit logs, so that is pure and testable (can you write tests currently?)