3.4 Executing programs

3.4.2 Application and library initialization

When a Dylan application starts up, it begins by loading the libraries that it uses. Each library performs its own initialization when it is loaded. In general, libraries are loaded in a demand-driven, depth-first order. However, you should not depend on used libraries being loaded in the same order that they are mentioned in a library definition.

Library initialization is performed by executing the code which comprises the library, in the order in which it is defined by the library's project. This means that the order of the Dylan source files in a project is significant, and that the order of definitions and expressions in a Dylan file is significant.

Definitions in a Dylan library are not, in general, said to execute. Rather, they define the static structure of a program. This is true of variables and constants initialized to literal values or other values computable at compile time, and it is also true of classes and functions. Forward references to such objects are allowed, and all such objects are created at the start of library initialization, before expressions are executed. Some definitions rely on the computation of run-time values; in these cases, forward references may not be allowed.

Expressions in a Dylan library are executed in the order in which they appear in the project, and the last expression in a project should be a call to a project's start function.