Ah silly me, another senior moment :-)
On Jun 8, 2012, at 12:06 PM, Robby Findler wrote: > Yes, of course it is and that first branch executes and thus the error > in the second branch (now a runtime error, thanks to the repl), is not > signaled. > > Robby > > On Fri, Jun 8, 2012 at 11:01 AM, Matthias Felleisen > <[email protected]> wrote: >> >> With all due respect, I disagree. Like Jens, I consider the (define u ..) >> nested and scoped inside the first cond branch. >> >> >> On Jun 8, 2012, at 11:56 AM, Sam Tobin-Hochstadt wrote: >> >>> On Fri, Jun 8, 2012 at 11:42 AM, Jens Axel Søgaard >>> <[email protected]> wrote: >>>> >>>> When >>>> >>>> (let ([x 1]) >>>> (cond >>>> [(= x 1) >>>> (define u 2) >>>> (+ u 1)] >>>> [else u])) >>>> >>>> is pasted into the interaction window, I get 3 ! >>>> >>>> I was expecting an error. >>> >>> This is the same behavior as: >>> >>> -> (if #f x 1) >>> 1 >>> >>> What's happening is that `#%top` behaves differently at the REPL than >>> in a module. This enables you to write: >>> >>> -> (define (even? x) (or (zero? x) (odd? (sub1 x)))) >>> -> (define (odd? x) (or (= x 1) (even? (sub1 x)))) >>> >>> without getting an error when entering the first line. >>> -- >>> sam th >>> [email protected] >>> >>> ____________________ >>> Racket Users list: >>> http://lists.racket-lang.org/users >> >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
