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- To: INFO-LISPM at MIT-AI
- From: RMS at MIT-AI (Richard M. Stallman)
- Date: Fri ,16 May 80 03:31:00 EDT
WHen new versions are installed, it will be possible to
decompose a list by saying (setf (list a b) foo)
or (setf (cons a b) foo), etc. list* is also allowed.
Quoted arguments to cons or list are ignored so
an arbitrary backquote pattern can be used:
(setf `(a ,b c ,d) foo) sets b to the cadr and d to the cadddr
doing nothing about a and c. Multiple levels of list structure work.
If foo evaluates to an atom you get an error.
Eventually there will be a match predicate macro which will
check that the a and c are there without setting the variables b or d.