The for expressions

We've seen the for loops, and how simple it is to use them in Scala. There's much more we can do with the for syntax. Here's an example:

object ForExpressions extends App {

   val person1 = Person("Albert", 21, 'm')
   val person2 = Person("Bob", 25, 'm')
   val person3 = Person("Cyril", 19, 'f')

   val persons = List(person1, person2, person3)

   for {
     person <- persons
     age = person.age
     name = person.name
     if age > 20 && name.startsWith("A")
   } {
     println(s"Hey ${name} You've won a free Gift Hamper.")
   }

 case class Person(name: String, age: Int, gender: Char)
 }

The following is the result:

Hey Albert You've won a free Gift Hamper. 

In the preceding example, we used a generator, definitions, and filters in the for expression. We used a for expression on a list of persons. We proposed a gift hamper for a person whose name starts with A and who is older than 20 years of age.

The first expression in for is a generator expression...