Understanding dictionaries

This is an introduction to dictionaries.

Dictionaries can store an unordered collection of elements, that will be accessed by key string, rather than by index as in arrays.

Dictionaries are used to implement a hash map (a.k.a. associative array).

DEFINE dict DICTIONARY OF INTEGER
LET dict["abcdef"] = 999

Dictionary elements can be of simple built-in types such as INTEGER, VARCHAR(n), RECORD structured types, or user-defined types. A dictionary can also be defined with built-in classes, imported module classes (from the Web Services extensions for example), or Java classes.