Using two backquotes and commas, Common Lisp

Question

I\'m learning common lisp and I have a problem with understanding the usage of two backquotes combined with two commas:

``(a ,,(+ 1 2))

I m

Answer 1

No, both commas were consumed. There were two levels of quoting and two levels of commas. Now there's one level of quoting and one level of commas. In fact, GNU Common Lisp (2.44.1) evaluates your expression as

(list 'a 3)

That's exactly the same thing as

`(a ,3)

but more explicitly has "evaluated" both commas.