Akin to Internet facilities, multiple threads of execution, and more dynamic streams, among the many
other facilities not standardized, a Common Lisp program has no true way to communicate program end.
This library is a reasonably comprehensive and well-designed interface to access this functionality.

This library is licensed under the Creative Commons Zero Public Domain Dedication.

I created the SHUT-IT-DOWN library to suit my needs for my work; when I was simplifying that work, I
decided to split this off into a separate library, which encouraged making it comprehensive so.  The
expected changes only involve supporting more implementations, and so no design changes.  Currently,
I lack solutions for Movitz and Lisp machines by ignorance, and MOCL, as mine enquiries are ignored.

My design entirely disregards anything beyond program exit, as many systems diverge in behaviour and
I find it entirely unimportant to acknowledge such.  The lone function QUIT has no parameters and in
the case of failure it returns no value.  In that common case of success, program exit should follow
immediately, yet some implementations have exit hooks and other such facilities which preclude this.

To properly use this, make certain the program should be able to exit and has entirely finished work
beforehand; implementations differ in how UNWIND-PROTECT is treated in this, and so avoid using QUIT
inside of one.  With regards to multiple threads of execution, try to reduce them to one first.  Any
otherwise standard program should have no issues using this library; this program is standard in the
sense it may be LOADed into a standard system and used, with merely a feature caveat if unsupported.

Know I don't consider this interface the ideal; that would have an optional UNWIND-PROTECT parameter
with NIL as the default, meaning to ignore them.  I could concede another optional parameter for the
purpose of communicating information to the underlying system, or having that parameter be an &REST.

Written in 2020,2021 by Prince Trippy.
This document is available under the CC0 Public Domain Dedication.
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