(mat uptr
  (begin
    (define-ftype A (struct [x double] [y wchar]))
    (define A->uptr (foreign-procedure "id" ((* A)) uptr))
    (define *int->uptr (foreign-procedure "id" ((* int)) uptr))
    (define a0 (make-ftype-pointer A 0))
    (define a-addr (foreign-alloc (ftype-sizeof A)))
    (define a (make-ftype-pointer A a-addr))
    (define i0 (make-ftype-pointer int 0))
    (define i-addr (foreign-alloc (ftype-sizeof int)))
    (define i (make-ftype-pointer int i-addr))
    #t)
  (eqv? (A->uptr #f) 0)
  (eqv? (A->uptr a0) 0)
  (eqv? (A->uptr a) a-addr)  ;; #f
  (eqv? (*int->uptr #f) 0)
  (eqv? (*int->uptr i0) 0)
  (eqv? (*int->uptr i) i-addr)  ;; #f
)