(define $main
  (lambda [$:]
    (do {[$: (write : "char : ")]
         [[$: $c] (read-char :)]
         [$: (write-char : c)]
         [$: (write-char : '\n')]
         [$: (write : "expr : ")]
         [[$: $e] (read :)]
         [$: (write : e)]
         [$: (write-char : '\n')]}
      :)))