
The example discussed here is included in the distribution files. There is
a main application file which uses module @tt{mm}. This module reads a line
from a file; the main predicate in the main file then prints this line.
The important thing is that the file read is named by a symbolic name
"@tt{file}". The main application file declares another file where the
symbolic names are assigned actual file names:

@begin{verbatim}
@include{examples/main.pl}
@end{verbatim}

Now, the file @tt{myfiles.pl} can be used to change the file you want to 
read from without having to recompile the application. The current 
assignment is:

@begin{verbatim}
@include{examples/myfiles.pl}
@end{verbatim}

@noindent
so the execution of the application will show the first line of
@tt{mm.pl}. However, you can change to:

@begin{verbatim}
file_alias(file,'main.pl').

@end{verbatim}

@noindent
and then execution of the same executable will show the first line of 
@tt{main.pl}. 


