Basic Information

To load a program from Emacs into Prolog, start up the Emacs/Prolog interface by typing prolog + at the main operating system prompt. When the Emacs/Prolog screen appears, type ^x ^f (for find-file) followed by the name of the file that contains your program. (Alternatively, you can type prolog + followed by the name of the file that contains your program.) After you enter the Emacs/Prolog environment, activate the window containing your file.

At this point, you have three options: you can load

• the entire buffer containing your file (<ESC> k b)
• a portion of the program that you have marked (<ESC> k r)
• or a single procedure (<ESC> k p)

Being able to load a designated portion of your program is very convenient if you are running a program and discover that you need to make a few changes to improve the program. You can make your changes and then reload just the changed portions, without reloading the entire program. If you are just beginning a Prolog session, however, you will probably want to load the entire buffer containing your program using <ESC> k b.

When you type <ESC> k, Emacs displays the following prompt line at the bottom of the screen:

     compile prolog ... enter p for procedure, r for region or b for buffer
     

In response, you can type b to load the entire buffer: or you can type r to load a region, or p to load a procedure, as described below.

After you indicate how much of your program to load, the cursor moves to the Prolog window, and Prolog displays a message that tells you it is loading the program. As it proceeds, Prolog displays messages to let you know which procedures are being loaded. For example, if your program consisted of procedures for parts_of/2, assembly/2, and inventory/2, Prolog would display the messages:

     % compiling procedure parts_of/2 in module user
     % compiling procedure assembly/2 in module user
     % compiling procedure inventory/2 in module user
     

After Prolog has finished loading, it displays a message such as:

     % compilation completed, 0.083 sec 448 bytes
     | ?-
     

At this point, you can begin to run your program (see bas-run).

Please notes:

1. When you load procedures into Prolog, Prolog first removes any previous versions of those procedures from its database, excepting those procedures that have been declared multifile. A multifile declaration indicates that a particular procedure is defined by clauses in more than one file. (For more information on multifile procedures, see sap-rge-dspn.) This is why the entirety of a procedure must be loaded at once; otherwise, loading the definition of the second part would wipe out the definition of the first part.
2. The <ESC> k commands can also be issued from the debugger prompt, as described in dbg-bas-bas .