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--- ch2_1_unquote [2021/04/18 03:46] – created admin
+++ ch2_1_unquote [2022/02/25 01:47] (current) – admin
@@ Line 6: / Line 6: @@
 >(setq b 3)       ; set value of symbol B
->`(a ,b c)        ; unquoted b
+>`(a ,b c)        ; unquoted B in backquouted list
 (A 3 C)           ; symbols A and C are not evaled, but B is
 </code>
+The last command is expanded to
+<code lisp>
+>(backquote (a (unquote b) c))
+</code>
+Following example was shown for backquote:
 <code lisp>
->(setq b 3)       ; set value of symbol B
+>`(a ,(+ 1 2) c)    ; backquoted list
+(A 3 C)             ; form (+ 1 2) evaluated
->`(a ,b c)        ; unquoted b
-(A 3 C)           ; symbols A and C not evaled, but B is
 </code>
+If the evaluated element results in list, with unquoting it becomes sub-list of the backqouted list.
+<code lisp>
+>`(a ,(list 1 2) c)    ; function LIST produces list
+(A (1 2) C)            ; list (1 2) as sublist
+</code>
+Important is that if we unqoute pre-existing list, this original list will become sublist, not a copy. ''SPLICE-UNQUOTE'' is different in this.
+See splice-unquote for further refinement. The forms ''BACKQUOTE'', ''UNQUOTE'' and ''SPLICE-UNQUOTE'' are useful for writing macros.