Spaceship Go

Constants

Booleans true and false are defined here. And in a very smart and concise way:

const (
    true = 0 == 0 // this is always true!
    false = 0 != 0 // this is always false!
)

Iota (view https://github.com/golang/go/wiki/Iota and https://golang.org/ref/spec#Iota) represents successive untyped integer constants.

const iota = 0 // Untyped int.

These two examples, describe how iota can be useful:

const (
	c0 = iota  // c0 == 0
	c1 = iota  // c1 == 1
	c2 = iota  // c2 == 2
)

const (
	a = 1 << iota  // a == 1  (iota == 0)
	b = 1 << iota  // b == 2  (iota == 1)
	c = 3          // c == 3  (iota == 2, unused)
	d = 1 << iota  // d == 8  (iota == 3)
)

Note: The << is a left shift operand, which shift lefts the operand by an integer (in this case iota value). So, for instance 1 << 2 equals 1 * 2 * 2.

nil is a widely used variable. It is defined as:

var nil Type

It represents the zero value of a type, within these clases: slices, pointer, map, func, interface, or channel.