Names

The Elan Programming Environment knows at any time a collection of names, each of which may be undefined, or have one or more definitions. Under the guidance and control of the Elan Programming Environment names can be manipulated and definitions supplied to form a program. All names which are known to the Elan Programming Environment are stored in the name list.

A name with which one or more definitions associated have been we will call a defined name. Depending on the way in which their definitions are brought into the Elan Programming Environment these are either visible or hidden. Definitions from packets (for example the standard Elan Library) are hidden, the others are visible. In an overview of known names the Elan Programming Environment will show only those names which have associated a visible definition.

Names which do not have any associated definition are called undefined. Once a name is mentioned to the Elan Programming Environment it will remain in the name list even when it is undefined. It is important to know this when using abbreviated names (see later).

Some names, as, for example, the keywords of Elan. Look like valid names, but no definition can be associated with them. These are called undefinable .