Learning Functional Programming in Go

Unit type

A tuple is a list of items that are ordered and immutable. You can select an element based on its position.

A unit type has exactly a one value. It is also known as the identity. The unit for multiplication is 1, for addition is 0, and for string concatenation, it is the empty string.

How many values can a type defined as a tuple of type int contain? Infinite (-∞, …, 0, 1, 2... ∞).

How many values can a type defined as the empty tuple contain? One. The unit is also represented as () in Haskell.

The value of a unit type is that you can use it in places where we might otherwise return nil (or null). We return a unit when we don't care what the value is. We don't return nil, we return a value; the unit value. All functions return values; ...