X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=src%2Fcode%2Fearly-type.lisp;h=6bc004ef62d06d79b4b6c2af12c8c4c6781344ab;hb=b2f0204834bd0c314d44942dd92475c15ffa8c89;hp=5b884768ea585dcc1f412a2b6268e9a2b07effc9;hpb=a682f4c392bc874a6a898632889319ebdd8821fc;p=sbcl.git

diff --git a/src/code/early-type.lisp b/src/code/early-type.lisp
index 5b88476..6bc004e 100644
--- a/src/code/early-type.lisp
+++ b/src/code/early-type.lisp
@@ -221,10 +221,15 @@
   ;; specifier to win.
   (type (missing-arg) :type ctype))
 
-;;; The NAMED-TYPE is used to represent *, T and NIL. These types must
-;;; be super- or sub-types of all types, not just classes and * and
-;;; NIL aren't classes anyway, so it wouldn't make much sense to make
-;;; them built-in classes.
+;;; The NAMED-TYPE is used to represent *, T and NIL, the standard
+;;; special cases, as well as other special cases needed to
+;;; interpolate between regions of the type hierarchy, such as
+;;; INSTANCE (which corresponds to all those classes with slots which
+;;; are not funcallable), FUNCALLABLE-INSTANCE (those classes with
+;;; slots which are funcallable) and EXTENDED-SEQUUENCE (non-LIST
+;;; non-VECTOR classes which are also sequences).  These special cases
+;;; are the ones that aren't really discussed by Baker in his
+;;; "Decision Procedure for SUBTYPEP" paper.
 (defstruct (named-type (:include ctype
                                  (class-info (type-class-or-lose 'named)))
                        (:copier nil))