[plt-scheme] When is (required ...) required in a formlet?

From: Todd O'Bryan (toddobryan at gmail.com)
Date: Sat Apr 24 23:16:40 EDT 2010

I just discovered that this formlet

(define login-formlet
   (div "Username:" ,{(to-string (required (text-input))) . => . username} (br)
      "Password:" ,{(to-string (required (password-input))) . => . password})
   `#hash((username . ,username)
          (password . ,password))))

doesn't work if I remove the (required ...) wrapping (text-input) and

I'm fine with that, but I don't really understand what it's doing and,
therefore, when I have to include it. Any insight?


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