anchor.diff:  ;;; is a character.  The other character types can be defined using
   ;;; this predicate and SATISFIES with a functions that check the range
   ;;; of the character code or by using a bitmap.
  -;;; 
  +;;;
   ;;; Stream types: stream, broadcast-stream, concatenated-stream,
   ;;; string-stream, echo-stream, synonym-stream, two-way-stream,
   ;;; file-stream.
  
positive.code: ;;; classes (as does STREAM), that are all pairwise disjoint.  So if
  ;;; we do not allow subclasses, then TYPEP for streams can be
  ;;; implemented by checking the CLASS-OF the object for equality (EQ)
  ;;; with the FIND-CLASS of the name. 
  ;;;
  ;;; Number types: number, ratio, bit, fixnum, bignum
  ;;;
  
negative.code: ;;; standard-generic-function, class, standard-class, built-in-class,
  ;;; structure-class, standard-object, structure-object, method,
  ;;; standard-method, method-combination,
  ;;;
  ;;; Others: t, null, nil, atom, hash-table, keyword, logical-pathname,
  ;;; list, compiled-function, package, pathname, random-state, symbol,
  ;;; readtable, sequence, restart,
  