What type of type management mechanism is applicable to generic types in programming languages?

Generic types in programming languages often use the mechanism of type constraints to manage types. This allows specifying requirements for generic parameter types, such as that the type must inherit from a certain class or implement an interface.

For example, in Swift, you can specify that a generic type must conform to a protocol:

func printElements<T: CustomStringConvertible>(items: [T]) {
    for item in items {
        print(item.description)
    }
}

Here, T is constrained to the CustomStringConvertible protocol, which guarantees the presence of the description property.

Thus, the type management mechanism for generics is the use of constraints, which allow controlling which types can be substituted into the generic parameter.