Scieneer Common Lisp 1.3.9 online documentation

ext:*use-implementation-types*[Variable]

*use-implementation-types* is a semi-public flag which determines how restrictive we are in determining type membership. If two types are the same in the implementation, then we will consider them them the same when this switch is on. When it is off, we try to be as restrictive as the language allows, allowing us to detect more errors. Currently, this only affects array types.