What data types are allowed as keys in a map structure?

In Go, the keys for a map can only be of types that support the comparison operation (comparable). This means that keys can be:

• Boolean values (bool)
• Numbers (int, float, complex, etc.)
• Strings (string)
• Pointers
• Interfaces, if the dynamic type supports comparison
• Structs, if all their fields are comparable

Slices, maps, functions, and other non-comparable types cannot be used as keys because they do not support the == operator.

Example:

m := make(map[string]int)
m["key"] = 42

// Struct with comparable fields
type Point struct {
    X, Y int
}

m2 := make(map[Point]string)
m2[Point{1,2}] = "A point"