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Re: How to use a symbol and its value to create alist?


From: Pascal J. Bourguignon
Subject: Re: How to use a symbol and its value to create alist?
Date: Tue, 11 Aug 2015 16:39:45 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux)

Navy Cheng <address@hidden> writes:

> For example:
>
> (setq a 1)
> (setq b 2)
> (setq c 3)
>
> How can I a alist, like:

How can you WHAT a alist?

> ((a . 1) (b . 2) (c .3))
>
> The value of a, b and c may change, so don't do this like
> (setq tree ((a . 1) (b . 2) (c .3)))

This is not a valid form, because (a . 1) is not a function name,
therefore it's not possible to apply it.



If you want to BUILD an a-list, you can use acons:

(let ((a 1)
      (b 2)
      (c 3))
  (let ((tree (acons 'a a (acons 'b b (acons 'c c '())))))
     tree))
--> ((a . 1) (b . 2) (c . 3))


-- 
__Pascal Bourguignon__                 http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
keep the man from touching the equipment.” -- Carl Bass CEO Autodesk


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