For Common Lisp, Modula-3, and Java, compare the semantics of unwindprotect and try...finally. Specifically, what happens if an exception arises within a cleanup clause? As noted near the end of...

For Common Lisp, Modula-3, and Java, compare the semantics of unwindprotect and try...finally. Specifically, what happens if an exception arises within a cleanup clause? As noted near the end of Section 9.6.2, an event-handler needs either to execute quickly or to pass its work off to another thread. A particularly elegant mechanism for the latter can be found in the async and await prim-itives of C# 5 and the similar async and let! of F#. Read up on the asynchronous programming model supported by these promitives. Explain their (implementation-level) connection to iterators (Section C 9.5.3). Write a GUI-based program or a network server that makes good use of them.