Compiling files

Earlier in this chapter we introduced the read-eval-print loop and explained that MCL actually compiles code entered into the Listener. Because the compiler is fast and you can recompile individual definitions, there is no noticeable delay.

Lisp source code is saved in text files. That is, the text of the definitions and other expressions is saved. The compiled forms of the expressions are not saved. When you restart Lisp and open the file, you need to recompile the functions in the file before you can use them. Recompiling can take some time when you are working on a large project.

To avoid the need to recompile files every time you restart Lisp, Macintosh Common Lisp provides a file compiler. The file compiler takes a source code file (that is, a text file of Lisp expressions), compiles the file, and saves the compiled version in another disk file. This compiled file, called a fasl file, can be loaded quickly into Lisp.

You can compile files by choosing the Compile File... command from the File menu. When you choose this command, MCL displays the choose-file dialog box, allowing you to choose a text file to compile. When you have selected a file, you are prompted for a name under which to save the file. The default is the name of the original text file, but with a different extension. The extension for fasl files in MCL 4.0 is ".pfsl". The extension for fasl files in MCL 3.1 is ".fasl".

You can also compile files by using the Common Lisp function compile-file.

Just as you can recompile individual definitions, you can recompile individual files. You do not need to recompile all the files in your project when only one of them has changed.

Gettmg Started with MCL - 19 OCT 1996

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