[racket-dev] [plt] Push #20578: master branch updated

Just using the core of even-read didn't work. It would start to read
after parse-statement had returned and then my parser would just sit
there because the port wasn't returning EOF. I think it is a bug.

Jay

On Fri, Jun 25, 2010 at 10:44 PM, Eli Barzilay <eli at barzilay.org> wrote:
> On Jun 26, jay at racket-lang.org wrote:
>> +  ; XXX This is almost certainly wrong.
>> +  (define (even-read src ip)
>> +    (begin0
>> +      (parameterize ([current-source-name src])
>> +       (datum->syntax #f (parse-statement ip)))
>> +      (current-read-interaction odd-read)))
>> +  (define (odd-read src ip)
>> +    (current-read-interaction even-read)
>> +    eof)
>> +
>> +  (current-read-interaction
>> +   even-read))
>
> This is not just wrong -- it is likely to break things randomly.
> Something like -- if you happen to invoke the datalog reader
> indirectly (like just `read' a file in the language), you'd end up
> with one of these readers as a side-effect.  This is exactly how the
> scribble/text language messed things up in a very confusing way: by
> banging `current-print' to do its own thing.
>
> --
>          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
>                    http://barzilay.org/                   Maze is Life!
>



-- 
Jay McCarthy <jay at cs.byu.edu>
Assistant Professor / Brigham Young University
http://teammccarthy.org/jay

"The glory of God is Intelligence" - D&C 93