P.S.
Can someone explain this?
// complex types in a few
type Employee =
| Worker of Person
| Manager of Employee listEmployee is a Sum Type i.e. it can either take a value of (Worker personObject) or (Manager [empObj1, empObj2...])
for instance, an binary tree would be
type Tree a =
| Leaf of a
| Node of (Tree a * Tree a)
t = Node (Node (Leaf 1, Leaf 2), Leaf 3) abstract class Employee {}
class Worker : Employee {
public Worker(Person o) {...}
}
class Manager : Employee {
public Manager(Employee[] o) {...}
} abstract sealed class Employee {
enum TAG { Worker, Manager }
readonly TAG tag;
Employee(TAG t) {
tag = t;
}
public class Worker : Employee {
public Worker(Person p) : base(TAG.Worker) { ... }
}
public class Manager : Employee {
public Manager(Employee[] o) : base(TAG.Manager) { ... }
}
}
Discriminated unions are sometimes called tagged unions because of the way they're implemented. It's typically more efficient to check the tag on the object than it is to test its type. The tag is used when pattern matching over the object.