(module phase mzscheme

  (require-for-syntax (lib "plt-match.ss"))

  (provide in-phase1 in-phase1/pass2)
  
  ;; Based on code from Ryan Culpepper:

  (define-syntax (in-phase1 stx)
    (syntax-case stx ()
      [(ip1 e)
       (match (syntax-local-context)
         ['expression
          #'(let-syntax ([_ e]) (void))]
         [(or 'module 'top-level (? pair?))
          #'(begin (define-syntax (macro stx*) (begin e #'(begin)))
                   (macro))]
         ['module-begin
          (raise-syntax-error #f "cannot be used as module body" stx)])]))

  (define-syntax (in-phase1/pass2 stx)
    (syntax-case stx ()
      [(ip1/p2 e)
       (match (syntax-local-context)
         [(? pair?)
          #'(define-values () (begin (in-phase1 e) (values)))]
         [(or 'expression 'top-level 'module 'module-begin)
          #'(#%expression (in-phase1 e))])]))

  )