Types

A type determines what shape a value has and what you can do with it.

You write the program body as a class (the shape of a program). Otherwise, when you define your own type, you use one of struct, record, enum, or union. class only allows declaration; instantiation and read/write are rejected (struct and record).

Pages per type

Page	Forms that compile	Forms that don’t compile	Contents
Primitive types	5	1
Arrays	48	19	An array holds a fixed number of values of the same type, decided in advance.
Enums	7	2
struct and record	34	7
Tuples	10	2
union (sum type)	8	3
Generics	29	11
Interfaces	23	9