How should I think about Scala's Product classes?

Question

The package \"scala\" has a number of classes named Product, Product1, Product2, and so on, up to Product22.

The descriptions of these classes are surely precise. Fo

Answer 1

"The set of all possible pairs of elements whose components are members of two sets."

"Specifically, the Cartesian product of two sets X (for example the points on an x-axis) and Y (for example the points on a y-axis), denoted X × Y, is the set of all possible ordered pairs whose first component is a member of X and whose second component is a member of Y (e.g. the whole of the x-y plane)"

Perhaps better understanding can be gained by knowing who derives from it:

Direct Known Subclasses: Tuple4

Or by, knowing it "extends Product", know what other classes can make use of it, by virtue of extending Product itself. I won't quote that here, though, because it's rather long.

Anyway, if you have types A, B, C and D, then Product4[A,B,C,D] is a class whose instances are all possible elements of the cartesian product of A, B, C and D. Literally.

Except, of course, that Product4 is a Trait, not a class. It just provides a few useful methods for classes that are cartesian products of four different sets.