It looks like prompt installs its own exception handler. So the 3 gets caught and reported by prompt, which then returns a default value of void and the call to + continues. This bears out with other examples, such as (list (prompt (raise 3))), which returns a list containing void.
Carl Eastlund On Wed, Dec 22, 2010 at 12:28 PM, Keiko Nakata <[email protected]> wrote: > I'm not sure if I got your point, as I seem to have the same result > after replacing with displayln. > > My concern is why I get a type error only for the latter? > (And how I could get both the exception and type error?) > > Keiko > > > From: Matthias Felleisen <[email protected]> > Subject: Re: [racket] raise-ing an exception inside prompt > Date: Wed, 22 Dec 2010 12:15:21 -0500 > >> >> Replace print with displayln. (You're buffering the output but it isn't >> displayed until the repl prints the next prompt.) >> >> >> On Dec 22, 2010, at 11:56 AM, Keiko Nakata wrote: >> >> > Hello, >> > >> > How should I understand this behavior? >> > >> > (with-handlers ([(lambda (_) #t) (lambda (_) (print "exit"))]) >> > (print (+ (prompt (print "hi") (raise 3) (print "bye")) 10))) >> > >> > prints "hi" then "exit", whereas >> > >> > (+ (prompt (print "hi") (raise 3) (print "bye")) 10) >> > >> > prints "hi", then I got an uncaught exception, followed by type error >> > of adding <void> and 10. >> > >> > Btw, where can I find the source code around exceptions, >> > e.g., raise and with-handlers? >> > >> > Thanks, >> > Keiko _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
