Functional Programming: A PragPub Anthology

Matching All the Things

So far we’ve just scratched the surface of pattern matching. Scala allows you to match based on values and types; you can even use guarded cases using if, as you’ll see next.

def process(message : Any) = {
  message match {
    case "hello" => println("received hello")
    case x : String => println("received a string " + x)
    case (a, b) => println("received tuple (" + a + ", " + b + ")")
    case 22 => println("received 22")
    case x : Int if x < 0 => println("received a negative number " + x)
    case y : Int => println("received number " + y)
  }
}

process(1, 2) // received typle (1, 2)
process("hello") // received hello
process("test")  // received a string test
process(22)      // received 22
process(12) // received number ...