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- To: Guy Steele <gls%AQUINAS@THINK.ARPA>
- Subject: Backquote idioms
- From: Robert W. Kerns <RWK@SCRC-YUKON.ARPA>
- Date: Wed, 22 May 85 18:59 EDT
- Cc: common-lisp@SU-AI.ARPA
- In-reply-to: <850522105634.1.GLS@MUNGO.ARPA>
Date: Wednesday, 22 May 1985, 10:56-EDT
From: Guy Steele <gls%AQUINAS@THINK.ARPA>
By the way, ',@x is not always an error! It does make sense if x is
exactly a singleton list. Sometimes this is useful in obscure cases.
Similarly, ,@',,@x makes sense if x is a singleton list. See the end of
I think "is an error" is still the right phrase to apply.
Just because there happens to be a value that does not result
in an error does not make it proper. I think it is *MUCH*
clearer to write ',(CAR X). You can do additional error
checking on X if you like, and signal a comprehensible
error, rather than depending on QUOTE to check! (I have
seen implementations where QUOTE did not check).