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sealed trait Shape

case class Circle(radius: Int) extends Shape

case class Rectangle(width: Int, height: Int) extends Shape

// 'match' keyword allows us to pattern match on a 
// specific option of the sum type
def area(shape: Shape): Double = shape match {
  case Circle(r) => math.Pi * r * r

vvviiimmm

-- The | can be read as 'or'
data Shape = Circle Int | Square Int

-- Alternatively 
data Shape
  = Circle { radius :: Int }
  | Square { side :: Int }

vvviiimmm

// Scala doesn't have a nice syntax for sum types so
// it looks like a familiar OOP inheritance tree.
sealed trait Shape

// But don't get confused: the 'extends' here stands for 'is'
// relationship, not in a sense of 'extends and overrides methods'.
// It only says that when you create a Circle it will be of type 'Shape'
case class Circle(radius: Int) extends Shape

case class Square(side: Int) extends Shape

vvviiimmm

-- Person is a product type consisting of 3 fields
data Person = Person
  { name :: String
  , age :: Int
  , address :: Address
  }

-- Address is a product type on its own
data Address = Address
  { country :: String

vvviiimmm

// Person is a product type consisting of 3 fields
case class Person(name: String, age: Int, address: Address)

// Address on its own also is a product type
case class Address(country: String, city: String, street: String)

// In order to create a Point you have to provide all 3 arguments
case class Point(x: Double, y: Double, z: Double)

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bob = Person "Bob" 42
 
olderBob = bob { age = 43 }

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val bob = Person("Bob", 42)

// .copy provided by the 'case class'
val olderBob = bob.copy(age = 43)

vvviiimmm

data Person = Person
  { name :: String
  , age :: Int
  , address :: Address
  }

-- Using type constructor
person = Person "Bob" 42

-- Or using records notation

vvviiimmm

case class Person(name: String, age: Int)

// Using type constructor
val person = Person("Bob", 42)

// Accessing fields
val personsAge = person.age

vvviiimmm

data Person = Person String Int

-- OR

data Person = Person
  { name :: String
  , age :: Int
  , address :: Address
  }