;;;; Additional pattern type definitions
+(defun el-search--split (matcher1 matcher2 list)
+ "Helper for the append pattern type.
+
+When a splitting of LIST into two lists L1, L2 exist so that Li
+is matched by MATCHERi, return (L1 L2) for such Li, else return
+nil."
+ (let ((try-match (lambda (list1 list2)
+ (when (and (el-search--match-p matcher1 list1)
+ (el-search--match-p matcher2 list2))
+ (list list1 list2))))
+ (list1 list) (list2 '()) (match nil))
+ ;; don't use recursion, this could hit `max-lisp-eval-depth'
+ (while (and (not (setq match (funcall try-match list1 list2)))
+ (consp list1))
+ (let ((last-list1 (last list1)))
+ (if-let ((cdr-last-list1 (cdr last-list1)))
+ ;; list1 is a dotted list. Then list2 must be empty.
+ (progn (setcdr last-list1 nil)
+ (setq list2 cdr-last-list1))
+ (setq list1 (butlast list1 1)
+ list2 (cons (car last-list1) list2)))))
+ match))
+
+(el-search-defpattern append (&rest patterns)
+ "Matches any list factorable into lists matched by PATTERNS in order.
+
+PATTERNS is a list of patterns P1..Pn. Match any list L for that
+lists L1..Ln exist that are matched by P1..Pn in order and L is
+equal to the concatenation of L1..Ln. Ln is allowed to be no
+list.
+
+When different ways of matching are possible, it is unspecified
+which one is chosen.
+
+Example: the pattern
+
+ (append '(1 2 3) x (app car-safe 7))
+
+matches the list (1 2 3 4 5 6 7 8 9) and binds `x' to (4 5 6)."
+ (if (null patterns)
+ '(pred null)
+ (pcase-let ((`(,pattern . ,more-patterns) patterns))
+ (cond
+ ((null more-patterns) pattern)
+ ((null (cdr more-patterns))
+ `(and (pred listp)
+ (app ,(apply-partially #'el-search--split
+ (el-search--matcher pattern)
+ (el-search--matcher (car more-patterns)))
+ (,'\` ((,'\, ,pattern)
+ (,'\, ,(car more-patterns)))))))
+ (t `(append ,pattern (append ,@more-patterns)))))))
+
(el-search-defpattern string (&rest regexps)
"Matches any string that is matched by all REGEXPS."
(el-search--check-pattern-args 'string regexps #'stringp)