Comprehensions
case class User(name: String, age: Int)
val userBase = List(User("Travis", 28),
User("Kelly", 33),
User("Jennifer", 44),
User("Dennis", 23))
val twentySomethings = for (user <- userBase if (user.age >=20 && user.age < 30))
yield user.name // i.e. add this to a list
twentySomethings.foreach(name => println(name)) // prints Travis Dennis
def foo(n: Int, v: Int) =
for (i <- 0 until n;
j <- 0 until n if i + j == v)
yield (i, j)
foo(10, 10) foreach {
case (i, j) =>
println(s"($i, $j) ") // prints (1, 9) (2, 8) (3, 7) (4, 6) (5, 5) (6, 4) (7, 3) (8, 2) (9, 1)
}
Have the form for (enumerators) yield e, where enumerators refers to a semicolon-separated list of enumerators.
Evaluate the body e for each binding generated by the enumerators and returns a sequence of these values.
Comprehensions → are a → Expressions.