[plt-scheme] expression context and units

I don't know if this is a bug, but it seems odd to me:

(require (lib "unitsig.ss")
         (lib "servlet-sig.ss" "web-server"))

(define test1 'test1)
(define-syntax foo1
  (syntax-rules ()
    [(_ bar)
     (define bar (quote bar))]))
(foo1 x)

(module m mzscheme
  (provide (all-defined))
  (define test3 'test3)
  (define-syntax foo3
    (syntax-rules ()
      [(_ bar)
       (define bar (quote bar))]))
  (foo3 xxx))  

(unit/sig ()
  (import servlet^)
  (define-syntax foo4
    (syntax-rules ()
      [(_ bar)
       (quote bar)]))
  (define xxxx (foo xxxx)))

(unit/sig ()
  (import servlet^)
  (define test2 'test2)
  (define-syntax foo2
    (syntax-rules ()
      [(_ bar)
       (define bar (quote bar))]))
  (foo2 xx))

; define: not allowed in an expression context in: (define xx (quote xx))

So, at the top level, a (define-syntax) does not leave expression
context, while in a unit it does, but only if the syntax has a define
inside IT.
-- 
Jay McCarthy <jay.mccarthy at gmail.com>
http://jay.makeoutcity.com/