+(defun gen-float (&key bound (type 'short-float))
+ "Returns a generator which producs floats of type TYPE. BOUND,
+if specified, constrains the ruselts to be in the range (-BOUND,
+BOUND)."
+ (lambda ()
+ (let* ((most-negative (ecase type
+ (short-float most-negative-short-float)
+ (single-float most-negative-single-float)
+ (double-float most-negative-double-float)
+ (long-float most-negative-long-float)))
+ (most-positive (ecase type
+ (short-float most-positive-short-float)
+ (single-float most-positive-single-float)
+ (double-float most-positive-double-float)
+ (long-float most-positive-long-float)))
+ (bound (or bound (max most-positive (- most-negative)))))
+ (coerce
+ (ecase (random 2)
+ (0 ;; generate a positive number
+ (random (min most-positive bound)))
+ (1 ;; generate a negative number
+ (- (random (min (- most-negative) bound)))))
+ type))))
+
+(defun gen-character (&key (code (gen-integer :min 0 :max (1- char-code-limit)))
+ (alphanumericp nil))
+ "Returns a generator of characters.
+
+CODE must be a generator of random integers. ALPHANUMERICP, if
+non-NIL, limits the returned chars to those which pass
+alphanumericp."
+ (lambda ()
+ (if alphanumericp
+ (loop
+ for count upfrom 0
+ for char = (code-char (funcall code))
+ until (alphanumericp char)
+ when (= 1000 count)
+ do (error "After 1000 iterations ~S has still not generated an alphanumeric character :(."
+ code)
+ finally (return char))
+ (code-char (funcall code)))))
+
+(defun gen-string (&key (length (gen-integer :min 0 :max 80))
+ (elements (gen-character))
+ (element-type 'character))
+ "Returns a generator which producs random strings. LENGTH must
+be a generator which producs integers, ELEMENTS must be a
+generator which produces characters of type ELEMENT-TYPE."