0. #lang racket
1. (require pict racket/draw)
2. (dc (lambda (dc dx dy)
3.       (define eye-path (new dc-path%))
4.       (send eye-path arc dx dy 50 100 0 pi)
5.       (send eye-path arc dx dy 50 50 pi 0 #f)
6.       (send eye-path close)
7.       (send dc draw-path dx dy 50 100))
8.      50 100)

=>

draw-path: contract violation

expected: (is-a?/c dc-path%)

given: 0

in: the 1st argument of

(->*m

((is-a?/c dc-path%))

(real? real? (or/c 'odd-even 'winding))

void?)

contract from: (class bitmap-dc%)

blaming: <pkgs>/pict-lib/pict/main.rkt

(assuming the contract is correct)