6.2.10 Include Declarations

A declaration

     :- include(Files).  ISO

where Files is a file name or a list of file names, instructs the processor to literally embed the Prolog clauses and directives in Files into the file being loaded. This means that the effect of the include directive is such as if the include directive itself was replaced by the text in the Files. Including some files is thus different from loading them in several respects:

• The embedding file counts as the source file of the predicates loaded, e.g. with respect to the built-in predicate source_file/2; see Read In.
• Some clauses of a predicate can come from the embedding file, and some from included files.
• When including a file twice, all the clauses in it will be entered twice into the program (although this is not very meaningful).

SICStus Prolog uses the included file name (as opposed to the embedding file name) only in source-linked debugging and error reporting. Note that source-linked debugging information is not kept for included files compiled to `.ql' format; in such cases the debugger will show the include directive itself as the source information.