查了r5rs的文档 操作符只有let let*和letrec 没有letcc 我是看The Seasoned Schemer 的 但是在DrRacket里letcc是红字啊 也就是说DrRacket不识别letcc

call-with-current-continuation

R5RS当然没，在Racket/base里……
实现估计是：
(define-syntax let/cc
(syntax-rules ()
((let/cc variable . body)
(call/cc (lambda (variable) . body)))))
不过我是看宏不爽的……
from RnRK:
($define! $let/cc ($vau (symbol . body) env (eval (list call/cc (list* $lambda (list symbol) body)) env)))
($define! call/cc (wrap ($vau (appv) env ($let/cc cont (apply appv (list cont) env)))))