AS
Извините за оффтоп, удаляюсь.
Ладно, написал свой макро:
(require racket/syntax)
(define-syntax (with-mode stx)
(syntax-case stx ()
[(_ mode body ...)
(let [(temp-mode #'(generate-temporary 'orig-mode))]
#'(let ((temp-mode some-mode))
(dynamic-wind
(lambda () (set! some-mode mode))
(lambda () body ...)
(lambda () (set! some-mode temp-mode)))))]))
(begin
(define some-mode 'mode-a)
(print-mode)
(with-mode 'mode-b
(print-mode)
(print-mode))) ;; => stdout: mode-a mode-b mode-b
