In my last post on Common Lisp, I mentioned how I learned that Common Lisp has a gradual/optional typing. Indeed, that was one of the many reasons that piqued me interested in the language.
However, it turns out that finding documentations or tutorials that teach how to use Common Lisp type declarations is harder than expected.
So the following is a hodgepodge collection of links related to type and type declarations in Common Lisp that I have found to be useful.
First is a paper (PDF) by Didier Verna. The paper describes how to use static typing to make Lisp as fast as C, and contains great examples on how to use type declarations to speed up Lisp code, as well as other optimization techniques, such as profiling, using the correct data structures, etc.
And last but not least is this little Q&A thread on StackOverflow, which contains concise examples of how to declare as well as check the types.