+(compile-time-defun do-case2-like (kind vform clauses)
+ "Helper function for `case2' and `ecase2'."
+ (with-gensyms (scrutinee argument)
+ `(multiple-value-bind (,scrutinee ,argument) ,vform
+ (declare (ignorable ,argument))
+ (,kind ,scrutinee
+ ,@(mapcar (lambda (clause)
+ (destructuring-bind
+ (cases (&optional varx vary) &rest forms)
+ clause
+ `(,cases
+ ,@(if varx
+ (list `(let ((,(or vary varx) ,argument)
+ ,@(and vary
+ `((,varx ,scrutinee))))
+ ,@forms))
+ forms))))
+ clauses)))))
+
+(defmacro case2 (vform &body clauses)
+ "VFORM is a form which evaluates to two values, SCRUTINEE and ARGUMENT.
+ The CLAUSES have the form (CASES ([[SCRUVAR] ARGVAR]) FORMS...), where a
+ standard `case' clause has the form (CASES FORMS...). The `case2' form
+ evaluates the VFORM, and compares the SCRUTINEE to the various CASES, in
+ order, just like `case'. If there is a match, then the corresponding
+ FORMs are evaluated with ARGVAR bound to the ARGUMENT and SCRUVAR bound to
+ the SCRUTINEE (where specified). Note the bizarre defaulting behaviour:
+ ARGVAR is less optional than SCRUVAR."
+ (do-case2-like 'case vform clauses))
+
+(defmacro ecase2 (vform &body clauses)
+ "Like `case2', but signals an error if no clause matches the SCRUTINEE."
+ (do-case2-like 'ecase vform clauses))
+