From: Nguyen Dao <hawaii.edu at ndao>
   
   Hi, I'm a new LISP learner. When I try
   (defclass people()
    ((name:type string)))
   it catch an error that no binding type for the Common Lisp symbol TYPE.
   What can I do to get rid of this error message?
   
It's uncertain what you intended here.  Whitespace matters: the form
as you give it above cannot even be read by a fresh lisp without
signalling error because

   name:type

refers to the symbol "TYPE" in the "NAME" package, and there is no
such package in a fresh lisp.  Even if there were such a package, then
this defclass slot specification would still be unsyntactic.

I would think you intended the following.  Note the whitespace
separating the symbols NAME and :TYPE.

   (defclass people()
    ((name :type string)))

This defclass form is syntactically correct and will be accepted
without error.

When you ask for help about a programming error, it is usually helpful
to include the actual error text, backtraces, etc.