When the demo is started, a window and a command menu are created.
Click in the input area and type an expression, such as
(+ 2 3) .
You must have the Java virtual machine installed to run this demo; you can get it for Windows (msjavx86.exe) here.
The best things in life are free: this demo uses the free software Gnu Common Lisp (GCL), XGCL, X windows [see also XFree86], Java, and WeirdX, a Java implementation of an X server.