Cannot typecheck (equal? (list) (list))

[dvanhorn]

With regular lists, (equal? (list) (list)) can be type checked, but not with random-access lists.

Welcome to DrRacket, version 5.0.1.3--2010-08-25(-/f) [3m].
Language: typed/racket; memory limit: 512 MB.
> (equal? (list) (list))
- : Boolean
#t
> (require (planet krhari/pfds:1:4/skewbinaryrandomaccesslist))
> (equal? (list) (list))
. Type Checker: Could not infer types for applying polymorphic function list
 in: (list)
. Type Checker: Could not infer types for applying polymorphic function list
 in: (list)
. Type Checker: Could not infer types for applying polymorphic function list
 in: (list)
. Type Checker: Could not infer types for applying polymorphic function list
 in: (list)
. Type Checker: Summary: 4 errors encountered in:
  (list)
  (list)
  (list)
  (list)