Start reading HtDP/2e @ http://www.ccs.neu.edu/home/matthias/HtDP2e/
It uses strings, which may be more familiar to you and which accommodate a bit more variety. Then switch back to HtDP/1e. On Jan 5, 2011, at 7:18 AM, Sayth Renshaw wrote: > > Can someone expand on the syntax for symbols? I can develop the check-guess > game simply without symbols but cannot with symbols. > Trying many versions of the symbol syntax but with no success. > > This the example for symbols, but how can I test conditions with a symbol? > (define (reply s) > (cond > [(symbol=? s 'GoodMorning) 'Hi] > > [( > symbol=? s 'HowAreYou?) 'Fine] > > [( > symbol=? s 'GoodAfternoon) 'INeedANap] > > [( > symbol=? s 'GoodEvening) 'BoyAmITired])) > > ;function check-guess > ;given number evaluate to one of three answers > ;number -> number -> string > > tested without symbols and got it working so was trying to emulate this with > symbols > > (define (check-guess guess target) > (cond > [(< guess target) "Too Small"] > [(= guess target) "Perfect"] > [(> guess target) "Too large"] > > > > ;(define (check-guess guess target) > ; (cond > ; [(symbol=? 'guess (< guess target) 'Too small)] > ; [(symbol=? 'guess (= guess target) 'Perfect)] > ; [(symbol=? 'guess (> guess target) 'Too Large)])) > > ;(define (check-guess guess target) > ; (cond > ; [(symbol=? (< guess target) 'True 'Too Small)] > ; [(symbol=? (= guess target) 'True 'Perfect)] > ; [(symbol=? (> guess target) 'True 'Too Large)])) > > ;(define (check-guess guess target) > ; (= s( < guess target)) > ; (= s( = guess target)) > ; (= s( > guess target)) > ; (cond > ; [(symbol= s 'true 'Too Small)] > ; [(symbol= s 'true 'Perfect)] > ; [(symbol= s 'true 'Too Large)])) > > ;(define (check-guess guess target) > ; [(symbol=? guess (< target guess) "Too small")] > > > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
