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- To: DLW at SCRC-TENEX at MIT-MC
- Subject: declarations
- From: Earl A. Killian <Killian at MIT-MULTICS>
- Date: Mon, 20 Sep 1982 17:35:00 -0000
- Cc: Common-Lisp at SU-AI
I think that you're overreacting. First, an implementation that really
wants to ignore variable declarations can have VAR-TYPE return T.
Second, you don't object to there being a standard way to access the
documentation string of a variable, do you? Is a declaration really all
that different? It is a form of documentation... KMP was asking for
concrete examples of VAR-TYPE use; the most compelling example to me is
simply me typing it at the debugger (or some code in the debugger that
does it automatically for me).
Also, I think Symbolics will be doing its users a disservice if it
chooses to ignore variable declartions. Given your current hardware,
there may not being any efficiency to be gained, but efficiency is only
one reason for declarations. Another reason, probably more important,
is that they help catch errors. For example, JMB once made a typo and
typed ESC ESC setq tab-equivalent CR to Multics EMACS, which set
tab-equivalent to (), which promptly blew everything away. You can
argue that there are better ways to handle this, but checking assertions
on variables is a nice general mechanism that can catch many errors;
it has all the good properties of making code read-only.