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The other day (perhaps yesterday) I was quite perplexed about this #+nil read-time conditional found in https://github.com/billstclair/defperson/blob/master/defperson.lisp#L289.
After some deep thinking I came to the conclusion that this is very lispy way of commenting out code. Can someone confirm this?
Perhaps my assumptions are completely wrong. Anyway, thanks in advance.
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Common Lisp is extensible through standard features such as Lisp macros (code transformations) and reader macros (input parsers for characters). Common Lisp provides partial backwards compatibility with Maclisp and John McCarthy's original Lisp. This allows older Lisp software to be ported to Common Lisp.
Traditionally, LISP can be interpreted or compiled -- with some of each running at the same time. Compilation, in some cases, would be to a virtual machine like JAVA. LISP is a general purpose programming language, but rarely used as such anymore.
Yes, it is a lispy way of commenting code, but you shouldn't leave this out in production code.
A better alternative is #+(or).
It only takes one more character, it takes the same key presses if you use Emacs paredit or some other mode that automatically inserts the closing parenthesis, and it's not subject to the existence of the symbol :nil in *features*.
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