Re: How the backquote and the comma really work?

[Marcin Borkowski <mbork@mbork.pl>]

On 2015-06-25, at 20:40, Michael Heerdegen <michael_heerdegen@web.de> wrote:

> Drew Adams <drew.adams@oracle.com> writes:
>
>> So `,foo evaluates variable foo, and `',foo evaluates foo and quotes
>> the result.
>
> Yes, that's an aspect that was missing in the mental model: backquote
> works recursively, i.e. unquoting at deeper list levels is handled as
> well.
>
>> (setq titi `',foo) ; => 'bar
>
> Whereby we don't want to conceal that the "'" is also a reader macro:
> 'thing -> (quote thing).
>
> Here is the expression the reader generates for "`',foo":
>
>   (read "`',foo") ==> (\` (quote (\, foo)))
>
> (be sure to eval with print-quoted nil, the default).

Interesting.  I have print-quoted set to nil, however, M-:
(eval-expression, or in my case - icicle-pp-eval-expression) does not
show what you have here.  Does eval-expression (or its Icicles
counterpart) mess with print-quoted?

> Michael.

Best,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University