Pattern Matching in Scala

pattern.scala

import java.util.Date
import java.text.DateFormat       
import java.text.DateFormat._    
 
val echoMath = """^echo (.*)""".r 
val countMath = """^count from (\d) to (\d)""".r


while (true) { 
  print("> ") // prompt
  
  scala.io.Source.stdin.getLine(0) match {
    case "hello" =>
      println("hi") 
    case "time" =>
      val currentDate = new Date
      val df = getDateInstance(LONG)
      println(df format currentDate)
    case echoMath(str) =>
      println(str)
    case countMath(a, b) =>
      val m = a.toInt
      val n = b.toInt
      for (i <- (m to n)) {
        print(i + ", ")
      }
      println("boom!")
    case "exit" => 
      println("bye")
      sys.exit
    
    case _ => println("command not matched")
  }
}

Example session:

> hello
hi
> time
May 12, 2012
> count from 1 to 7
1, 2, 3, 4, 5, 6, 7, boom!
> echo are you there?
are you there?
> sudo make me a sandwich
command not matched
> exit
bye