[racket] how to design programs chap5 error!!!

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Mon Nov 29 22:10:26 EST 2010

How did you produce this error message? 

When I run this program: 

  (require htdp/master)
  (define (check-color x y z w)   x)
  (master check-color)

I get no error whatsoever.  I also don't get an error when I run 

 > (master check-color)

in the interactions area: 

Welcome to DrRacket, version [3m].
Language: Beginning Student.
> (master check-color)

-- Matthias

On Nov 28, 2010, at 6:58 AM, 邢泉 wrote:

> Hi:
> Help Me! Thanks! 
> > (master check-color)
> check-color: this is a procedure, so it must be applied to arguments (which requires using a parenthesis before the name)
> 2010-11-28
> Q.Xing
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