[racket] Definitions in cond-bodies

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
<matthias at ccs.neu.edu> 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
>> <jensaxel at soegaard.net> 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
>> samth at ccs.neu.edu
>>
>> ____________________
>>  Racket Users list:
>>  http://lists.racket-lang.org/users
>
>
> ____________________
>  Racket Users list:
>  http://lists.racket-lang.org/users