[racket] the extra empty string

On Fri, Apr 19, 2013 at 6:47 PM, Kejia柯嘉 <w.kejia at gmail.com> wrote:
> Hi Yoo,
>
> You may try (display '("" "0" "" "0")), and you will find two whitepaces
> between 0.


The function "display" delimits between elements of a list by
inserting a space between each pair.  It simply turns out that
displaying the empty string doesn't do anything.  The output you're
seeing should be consistent with that behavior.

Given:

     '("" "0" "" "0")

It is displaying:

   the left-paren,
   the "",
   the space delimiter,
   the "0",
   the space delimiter,
   the "",
   the space delimiter,
   the "0",
   the right-paren.


Why are you using display to look at the content of lists?  Usually,
write or print is more appropriate:

http://docs.racket-lang.org/guide/read-write.html




>
> 在 2013年4月19日星期五，Danny Yoo 写道：
>
>> On Fri, Apr 19, 2013 at 5:44 PM, Kejia柯嘉 <w.kejia at gmail.com> wrote:
>> > Hi all,
>> >
>> > In DrRacket, why is there an extra empty string (`[]`between 0s) in
>> > the list:`'("" "0" "" "0")`. This generates `([]0[][]0)`, instead of
>> > `([]0[]0)`.
>>
>>
>> Unfortunately, the question here is ambiguous.  What are you trying to
>> do?  Can you show us the code you are using to distinguish the empty
>> string?  What expression are you trying to evaluate such that you get
>> this list in the first place?
>
>
>
> --
>
> ☵☯☲
>
>