+(defstruct
+ (registerv (:constructor nil)
+ (:constructor registerv--make (&optional data print-func
+ jump-func insert-func))
+ (:copier nil)
+ (:type vector)
+ :named)
+ (data nil :read-only t)
+ (print-func nil :read-only t)
+ (jump-func nil :read-only t)
+ (insert-func nil :read-only t))
+
+(defun* registerv-make (data &key print-func jump-func insert-func)
+ "Create a register value object.
+
+DATA can be any value.
+PRINT-FUNC if provided controls how `list-registers' and
+`view-register' print the register. It should be a function
+receiving one argument DATA and print text that completes
+this sentence:
+ Register X contains [TEXT PRINTED BY PRINT-FUNC]
+JUMP-FUNC if provided, controls how `jump-to-register' jumps to the register.
+INSERT-FUNC if provided, controls how `insert-register' insert the register.
+They both receive DATA as argument."
+ (registerv--make data print-func jump-func insert-func))
+