Recursion isn't the problem. Your use of it is, however. Replace it with "arg" and see what happens.
On Dec 30, 2013, at 4:33 PM, 亀田馬志 <masashi.kam...@gmail.com> wrote: > Yes. Actually I try making an old-fashoned game, like Lemonade Stand on Apple > ][, and this is a part of the code. It controls input of the game. > > Is this a problem around recursive? Isn't it good idea to use 'read' with a > recursive structure? > > > 2013/12/31 Matthias Felleisen <matth...@ccs.neu.edu> > > On Dec 30, 2013, at 4:03 PM, 亀田馬志 <masashi.kam...@gmail.com> wrote: > > > (require srfi/13) > > > > (define (yes-or-no? arg) > > ; expected it returns #t or #f > > ; depending on input such as yes or no > > (letrec ((y-or-n? > > ; if argument is either Y or YES, > > ; it returns #t otherwise #f > > (lambda (sym) > > (and (memq sym '(Y YES)) #t))) > > (symbol-upcase > > ; confirm any symbol into uppercase > > (lambda (arg) > > (if (symbol? arg) > > (string->symbol (string-upcase (symbol->string arg))) > > (yes-or-no? (read)))))) > > Do you really want to recur here? > > > > (let ((sym (symbol-upcase arg))) > > (if (memq sym '(Y YES N NO)) > > (y-or-n? sym) > > (yes-or-no? (read)))))) > > > > I expected that (cond ((I input y or yes) returns #t) > > ((I input n or no) returns #f) > > (else this procedure waits something)) > > > > > ____________________ Racket Users list: http://lists.racket-lang.org/users
