Question

Did some examples… on Scala’s REPL.

I totally forgot to type Array when instantiating an Array object (trying to test ++ operator).

Anyway, now I’m wondering what datatype is this?

val one = (1,2,3) 

Or what data structure or container is the code above? What is this call? Why is it useful? I don’t believe the REPL gave any useful information on what the above code is.

Thank you for your time.

Answer 1

This is special syntax for constructing a Tuple3 object. It’s equivalent to

val one = Tuple3[Int, Int, Int](1, 2, 3)

Tuples are defined up to Tuple22. One important use case for tuples is returning multiple values from a function. Tuples can also be unpacked with special syntax:

scala> val (a, b, c) = one
a: Int = 1
b: Int = 2
c: Int = 3