[racket] what is this thing: '#(struct:foo 3 4) ?

On Sep 10, 2010, at 9:34 AM, Matthew Flatt wrote:

> At Fri, 10 Sep 2010 09:21:28 -0700, John Clements wrote:
>> I've spent long enough with the docs on this not to feel too embarrassed about 
>> this question: what kind of value is produced by
>> 
>> '#(struct:foo 3 4)
>> 
>> (N.B. the leading quote)
> 
> Are you by chance using the PLAI language that is distributed with 5.0.1?
> 
> I ask because this looks like something that would be produced by the
> broken printer in that version.

No:

#lang racket

(define-struct foo (a b) #:transparent)

(define o (open-output-string))
(write (make-foo 3 4) o)
(read (open-input-string (get-output-string o)))

=>

Welcome to DrRacket, version 5.0.1.5--2010-09-08(93ee20e/g) [3m].
Language: racket; memory limit: 256 MB.
(foo 3 4)
'#(struct:foo 3 4)
> 


And to everyone else: D'oh! Okay, I do feel embarrassed.

John


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