<div dir="ltr">No, you don't have to do anything. The #f is an internal detail that is no longer exposed to the user, so I should probably remove it from the documentation. </div><div class="gmail_extra"> <div>Carl Eastlund</div> <div class="gmail_quote">On Wed, Aug 28, 2013 at 5:14 AM, Tobias Hammer <<a href="mailto:tobias.hammer@dlr.de" target="_blank">tobias.hammer@dlr.de</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Hi, from the docs on #:methods argument to struct: "If #:methods gen:name method-defs is provided, then gen:name must be a transformer binding for the static information about a generic group produced by define-generics. The method-defs define the methods of gen:name. If any method of gen:name is not defined, then #f is used to signify that the structure type does not implement the particular method. [...]" Can anyone explain the part with the #f to me? Does it mean that i have to (define some-gen-fun #f) to indicate it's not implemented? But that seems to have no real impact as i get the exactly same error with just leaving it out? Thanks for any clarification. Tobias -- --------------------------------------------------------- Tobias Hammer DLR / Robotics and Mechatronics Center (RMC) Muenchner Str. 20, D-82234 Wessling Tel.: 08153/28-1487 Mail: <a href="mailto:tobias.hammer@dlr.de" target="_blank">tobias.hammer@dlr.de</a> ____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </blockquote></div> </div>