[racket] Some newbie trouble on running Web Server on EC 2

From: Danny Yoo (dyoo at cs.wpi.edu)
Date: Thu Apr 21 23:16:11 EDT 2011

[Please keep racket-lang in CC.]

> Is the help mainly for simpler #lang like Beg Stud? (#lang racket
> seems to have lots of place where [ appears and inside xexpr as well.
> So it may not be all that easy to keep track for Dr, I am guessing.)

It is meant to enforce a particular paren style for Racket.  I'd say
it's more of a general Racket convention than a Beginner Student
convention, since it helps professional Racketeers as well.

Even though '[' is interchangeable with '(', the parens do have to
match with their corresponding ']' and ')'.  Because of that, the
distinguished paren shapes help to localize paren mismatch errors when
they occur.  e.g. the error that's produced when tryting to evaluate:

    (define x 16)
    (cond [(equal? x 42

will point at the ']'.

The editor has these paren styles built in to specific forms.  You can
see which forms get affected by looking at Preferences/Editing/Square

Personally, I would leave them on and let DrRacket manage the parens for me.

Posted on the users mailing list.