Arrays, sets, lists, and records

The Mosel language defines the structured types set, array, list, and record. So far we have worked with arrays and sets relying on an intuitive understanding of what is an `array' or a `set'. More formally, we may define an array as a collection of labeled objects of a given type where the label of an array entry is defined by its index tuple.

A set collects objects of the same type without establishing an order among them (as opposed to arrays and lists). Set elements are unique: if the same element is added twice the set still only contains it once.

A list groups objects of the same type. Unlike sets, a list may contain the same element several times. The order of the list elements is specified by construction.

Mosel arrays, sets and lists may be defined for any type, that is the elementary types (including the basic types integer, real, string, boolean and the MP types mpvar and linctr), structured types (array, set, list, record), and external types (contributed to the language by a module).

A record is a finite collection of objects of any type. Each component of a record is called a field and is characterized by its name and its type.

This chapter first presents in a more systematic way the different possibilities of how arrays and sets may be initialized (all of which the reader has already encountered in the examples in the first part), and also shows more advanced ways of working with sets. We then introduce lists, showing how to initialize and access them, and finally give some examples of the use of records.