(define-type pad-dims (vector integer integer integer integer))
(define-type real-pad-dims (vector fixnum fixnum fixnum fixnum)) ;< pad-dims

(define-type pad-chars (vector (or false char) (or false char) (or false char) (or false char)))

(define-type shape-info vector)

(define-type real-shape-plotter (#!optional canvas fixnum fixnum -> (or canvas shape-info)))
(define-type shape-plotter (#!optional canvas integer integer -> (or canvas shape-info)))

(define-type shape-plotters (list-of shape-plotter))

(define-type real-shape real-shape-plotter)
(define-type shape shape-plotter)

(define-type real-shape-creator (#!rest * -> real-shape-plotter))
(define-type shape-creator (#!rest * -> shape-plotter))