<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><div><div>On May 2, 2014, at 9:24 PM, <a href="mailto:dfeltey@ccs.neu.edu">dfeltey@ccs.neu.edu</a> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">#:implements should be used inside of a Class type form.<br><br>The following is an example from the documentation:<br><br><blockquote type="cite">(define-type Point<%> (Class (field [x Real] [y Real])))<br>(: colored-point% (Class #:implements Point<%><br></blockquote> (field [color String])))<br></blockquote><div>I tried this:</div><div><div><font face="Courier New">#lang typed/racket</font></div><div><font face="Courier New"><br></font></div><div><font face="Courier New">(module untyped racket</font></div><div><font face="Courier New"> (provide point% colored-point%)</font></div><div><font face="Courier New"> (define point%</font></div><div><font face="Courier New"> (class object% (super-new) (inspect #f)</font></div><div><font face="Courier New"> (init-field x y)))</font></div><div><font face="Courier New"> (define colored-point%</font></div><div><font face="Courier New"> (class point% (super-new) (inspect #f)</font></div><div><font face="Courier New"> (init-field color))))</font></div><div><font face="Courier New"><br></font></div><div><font face="Courier New">(define-type Point<%> (Class (field [x Real] [y Real])))</font></div><div><font face="Courier New">(require/typed (submod "." untyped)</font></div><div><font face="Courier New"> [colored-point% (Class #:implements Point<%></font></div><div><font face="Courier New"> (field [color String]))])</font></div><div>And it gave me this error:</div><div><font face="Courier New">. Type Checker: not a valid type: #:implements in: #:implements</font></div></div><br></div><br></body></html>