A tuple is a heterogeneous collection of two to twenty-two values. A tuple can be defined using parentheses. For tuples of size
2 (also called a 'pair') there's an arrow syntax.
scala> val x = (1, "hello") x: (Int, String) = (1,hello) scala> val y = 2 -> "world" y: (Int, String) = (2,world) scala> val z = 3 → "foo" //example of using U+2192 RIGHTWARD ARROW z: (Int, String) = (3,foo)
x is a tuple of size two. To access the elements of a tuple use
._22. For instance, we can use
x._1 to access the first element of the
x._2 accesses the second element. More elegantly, you can use tuple extractors.
The arrow syntax for creating tuples of size two is primarily used in Maps, which are collections of
(key -> value) pairs:
scala> val m = Map[Int, String](2 -> "world") m: scala.collection.immutable.Map[Int,String] = Map(2 -> world) scala> m + x res0: scala.collection.immutable.Map[Int,String] = Map(2 -> world, 1 -> hello) scala> (m + x).toList res1: List[(Int, String)] = List((2,world), (1,hello))
The syntax for the pair in the map is the arrow syntax, making it clear that 1 is the key and a is the value associated with that key.