[racket] choice% - replace all choices

hello, is there a way to replace all the choices at one whack? i have choice lists several hundred items long, which to reset with choice% methods clear, append will be tedious the only way i can see is to work on a parent area-container% with change-children, but that also looks tedious. it

[racket] (if ...) form without an else

usually an (if ...) form without an else part does not cause an error. but sometimes it does, as the following shows: if: bad syntax (must have an "else" expression) in: (if isinitialised (expose)) why the different behavior? -- http://www.fastmail.fm - A fast, anti-spam email service.

[racket] where are lib locations given?

hello, where do i find the required lib when using a form, such as (struct ...)? neither the guide, under 5 Programmer-Defined Datatypes http://download.racket-lang.org/docs/5.2/html/guide/define-struct.html nor the manual, under 4 Structures http://download.racket-lang.org/docs/5.2/html/refer

[racket] error from web-server tutorial

re: http://download.plt-scheme.org/doc/4.2.1/html/continue/index.html hello, i am having trouble getting to run the 1st example in tutorial "Continue: Web Applications in PLT Scheme", here: #lang web-server/insta (define (start request) '(html (head (title "My Blog")) (body (h1