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fix the while macro for Common Lisp

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Earlier version was incorrect, as it only executed `body` once and then terminated, like an if statement instead.
This commit is contained in:
Aaron Zeng 2015-04-21 15:08:39 -04:00
parent a5d38aedd5
commit 6b2d8d5fe2
1 changed files with 5 additions and 3 deletions
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8
common-lisp.html.markdown
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@ -573,13 +573,15 @@ nil ; for false - and the empty list
"While `condition` is true, `body` is executed. "While `condition` is true, `body` is executed.
`condition` is tested prior to each execution of `body`" `condition` is tested prior to each execution of `body`"
(let ((block-name (gensym))) (let ((block-name (gensym)) (done (gensym)))
`(tagbody `(tagbody
,block-name
(unless ,condition (unless ,condition
(go ,block-name)) (go ,done))
(progn (progn
,@body) ,@body)
,block-name))) (go ,block-name)
,done)))
;; Let's look at the high-level version of this: ;; Let's look at the high-level version of this: