Function prints fine in debug window, but when using the aserve html macro, only nil is printed. (html ((:pre ) (:princ (show-frame symbol)))) The show-frame function prints to *standard-output*, and not to *html-stream*. Function prints to *standard-output* or another output stream which you know. Wrap printing code with (with-output-to-string (*output-stream*) ...) where *output-stream* is the stream that the function normally prints to. (html ((:pre ) (:princ (with-output-to-string (*standard-output*) (show-frame symbol))))) Code compiles fine, but when trying to run, get an error that says: "Exception in thread "main" java.lang.NoClassDefFoundError: ..." java MyClass The java interpreter cannot find your class. This is a problem with the classpath, a variable which tells java where to find your classes. Must be able to set system properties. Set the system property "classpath" to point to where your java classes are. set classpath="." java MyClass> None. Pass the classpath into the java interpreter. java -classpath "." MyClass