[R6RS] Semantics of `raise'
William D Clinger
will at ccs.neu.edu
Mon Mar 13 11:42:02 EST 2006
>From our previous discussion, I think the intended semantics of
Raises a continuable exception by invoking the current exception
handler on obj. The handler is called with a continuation that is
equivalent to the continuation of the call to `raise-continuable'
with these two exceptions: (1) the current exception handler is
the one that was in place for the call to `with-exception-handler'
that installed the handler being called, and (2) if the handler
being called returns, then it will again become the current
exception handler. If the handler returns, the value(s) it
returns become(s) the value(s) returned by the call to
In terms of the reference implementation, I think the intended
semantics of raise-continuable could be written like this:
(define (raise-continuable obj)
(let ((handlers *current-exception-handlers*))
(with-exception-handlers (cdr handlers)
(lambda () ((car handlers) obj))
(apply values vals)))))))))
The code above has not been tested.
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