[racket] Custom language using syntax/module-reader with #:wrapper1

Is it possible that you missed out on #%top-interaction? 

http://docs.racket-lang.org/reference/__top-interaction.html?q=%23%25top#(form._((lib._racket/private/base..rkt)._~23~25top-interaction))


On May 29, 2012, at 7:44 PM, Nick Sivo wrote:

> Hi,
> 
> I'm trying to implement arc as a racket language extension.  To become
> familiar with racket's reader infrastructure, I thought I'd start with
> something simple:
> 
> ==================
> kogir/arc/lang/reader.rkt:
> ==================
> #lang s-exp syntax/module-reader
> (planet kogir/arc/language)
> #:wrapper1 arc-read-wrapper
> 
> (require (planet kogir/arc/reader))
> 
> ==============
> kogir/arc/reader.rkt:
> ==============
> #lang racket/base
> 
> (provide make-arc-readtable
>         arc-read-wrapper)
> 
> (define (read-square-brackets ch port src line col pos)
>  (datum->syntax
>   #f
>   `(lambda (_)
>       ,(read-syntax/recursive src port #\[ #f))
>   (let-values ([(l c p) (port-next-location port)])
>         (list src line col pos (and pos (- p pos))))))
> 
> (define (make-arc-readtable)
>  (make-readtable (current-readtable)
>                  #\[ 'terminating-macro read-square-brackets))
> 
> (define (arc-read-wrapper thunk read-syntax)
>  (parameterize ([current-readtable (make-arc-readtable)])
>    (thunk)))
> 
> ================
> kogir/arc/language.rkt:
> ================
> #lang racket
> 
> (provide (all-defined-out)
>         (all-from-out racket))
> 
> I expected it to give me a language very similar to racket, but with
> arc's [ _ ] lambda syntax sugar:
> [+ _ 1] => (lambda (_) (+ _ 1))
> 
> When I test in Dr. Racket, it works for reading files, but not in the
> interaction window:
> 
> ======
> test.arc:
> ======
> #lang planet kogir/arc
> 
> (define test [+ _ 1])
> 
> ---------------------------------------------------------------------------------------
> 
> Welcome to DrRacket, version 5.2.1 [3m].
> Language: planet kogir/arc [custom]; memory limit: 128 MB.
>> test
> #<procedure:test>
>> (test 1)
> 2
>> [+ _ 1]
> . _: wildcard not allowed as an expression in: _
> 
> What pieces am I missing to make the Dr. Racket interaction window
> support the new syntax?
> 
> Also, is it correct in kogir/arc/reader.rkt to use
> `(lambda (_)
>       ,(read-syntax/recursive src port #\[ #f)
> or should I use
> #`(lambda (_)
>       #,(read-syntax/recursive src port #\[ #f)
> 
> Both appear to work?
> 
> Any pointers you might have would be awesome.  I apologize in advance
> if I missed something obvious.
> 
> Thanks,
> Nick
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