How is ISLISP related to Common Lisp?
A–> ISLISP is what Kent Pitman has sometimes called “culturally compatible” with Common Lisp, in the sense that it doesn’t introduce any concepts or data structures or classes that are greatly at odds with what Common Lisp uses. A compatibility package for ISLISP could be written entirely in portable Common Lisp. (Kent Pitman has done this privately to make sure it was possible; contact him for details.) ISLISP is not a subset of Common Lisp in the sense of being able to run a subset of code offered by Common Lisp. Conceptually, however, it is like a subset in that it offers what is largely a subset of Common Lisp’s functionality. The Common Lisp specification is about 1150 pages in hardcopy. The ISLISP specification is about a tenth the size of that, and the functionality it offers is correspondingly less. Text pages are only a rough metric of the capability, of course. But the ISLISP specification is small enough that you might prefer to simply browse it to find out what’s in it. To
