Route 477(2009-09-09)

2009-09-09

■ [scheme][english] R6RS仕様の英文をLisp的に読み解いてみる

例外のところを読んでいるのですが、複雑すぎて意味が分からない英文が。

Raises a non-continuable exception by invoking the current exception handler on obj. The handler is called with a continuation whose dynamic environment is that of the call to raise, except that the current exception handler is the one that was in place when the handler being called was installed.

[r6rs-libより引用]

Lisp的にインデントしてみると、一文目は

(Raises a non-continuable exception
  (by invoking the current exception handler on obj)).

こうですよね。問題は二文目。

(The handler is called with (a continuation
                              (whose dynamic environment
                                is
                                (that of (the call to raise)))),
  (except that
    (the current exception handler
      is
      (the one
        (that was in place
          (when (the handler being called) was installed)))))).

こう？