(list ,(+ 1 2) 4) =) (list 3 4)
(let ((name 'a)) (list ,name ',name))
=) (list a (quote a))
(a ,(+ 1 2) ,@(map abs '(4 -5 6)) b)
=) (a 3 4 5 6 b)
(( foo ,(- 10 3)) ,@(cdr '(c)) . ,(car '(cons)))
=) ((foo 7) . cons)
#(10 5 ,(sqrt 4) ,@(map sqrt '(16 9)) 8)
=) #(10 5 2 4 3 8)
Quasiquote forms may be nested. Substitutions are made
only for unquoted components appearing at the same nesting
level as the outermost backquote. The nesting level increases
by one inside each successive quasiquotation, and
decreases by one inside each unquotation.
(a (b ,(+ 1 2) ,(foo ,(+ 1 3) d) e) f)
=) (a (b ,(+ 1 2) ,(foo 4 d) e) f)
(let ((name1 'x)
(name2 'y))
(a (b ,,name1 ,',name2 d) e))
=) (a (b ,x ,'y d) e)
The two notations hqq templatei and (quasiquote
hqq templatei) are identical in all respects. ,hexpressioni
is identical to (unquote hexpressioni), and ,@hexpressioni
is identical to (unquote-splicing hexpressioni). The external
syntax generated by write for two-element lists
whose car is one of these symbols may vary between implementations.
(quasiquote (list (unquote (+ 1 2)) 4))
=) (list 3 4)
'(quasiquote (list (unquote (+ 1 2)) 4))
=) (list ,(+ 1 2) 4)
i.e., (quasiquote (list (unquote (+ 1 2)) 4))
Unpredictable behavior can result if any of the symbols
quasiquote, unquote, or unquote-splicing appear in positions
within a hqq templatei otherwise than as described
above.