Scala Programming Projects

Usage examples

Suppose that you are building a program to manage a shop's inventory. The following is a simplified API to manage the items:

import cats.{Id, Monad}import cats.implicits._case class Item(id: Int, label: String, price: Double, category: String)trait ItemApi[F[_]] { def findAllItems: F[Vector[Item]] def saveItem(item: Item): F[Unit]}

The API is parametrized with an F context. This allows you to have different implementations of your API, as follows:

• In your unit tests, you would use class TestItemApi extends ItemApi[cats.Id]. If you look for the definition of Id, you will find type Id[A] = A. This means that this TestItemApi can directly return Vector[Item] in findAllItems, and Unit in saveItem.
• In your production code, you ...