Add -insert-sorted

dash.el

@@ -881,6 +881,23 @@ See also: `-splice', `-splice-list'"
   (let ((split-list (-split-at n list)))
     (nconc (car split-list) (cons x (cadr split-list)))))
 
+(defun -insert-sorted (comparator item list)
+  "Using COMPARATOR insert ITEM into sorted LIST.
+
+It is assumed that LIST is already sorted on input.
+
+The new item is inserted at the first position where
+
+  (funcall comparator x item)
+
+returns nil.  X is the \"current\" item from the input list."
+  (let ((place (-split-with (lambda (x) (funcall comparator x item)) list)))
+    (-concat (car place) (list item) (cadr place))))
+
+(defmacro --insert-sorted (form item list)
+  "Anaphoric form of `-insert-sorted'."
+  `(-insert-sorted (lambda (it other) ,form) ,list))
+
 (defun -replace-at (n x list)
   "Return a list with element at Nth position in LIST replaced with X.
 
@@ -2640,6 +2657,8 @@ structure such as plist or alist."
                              "-split-at"
                              "-rotate"
                              "-insert-at"
+                             "-insert-sorted"
+                             "--insert-sorted"
                              "-replace-at"
                              "-update-at"
                              "--update-at"

dev/examples.el

@@ -256,6 +256,13 @@ new list."
     (-insert-at 1 'x '(a b c)) => '(a x b c)
     (-insert-at 12 'x '(a b c)) => '(a b c x))
 
+  (defexamples -insert-sorted
+    (-insert-sorted '< 4 '(1 2 3 5 6 7)) => '(1 2 3 4 5 6 7)
+    (-insert-sorted (lambda (a b) (< (car a) (car b))) '(3 . "new") '((1) (2) (3 . "old"))) => '((1) (2) (3 . "new") (3 . "old"))
+    (-insert-sorted '< 1 '(2 3 5 6 7)) => '(1 2 3 5 6 7)
+    (-insert-sorted '< 8 '(2 3 5 6 7)) => '(2 3 5 6 7 8)
+    (-insert-sorted '< 1 nil) => '(1))
+
   (defexamples -replace-at
     (-replace-at 0 9 '(0 1 2 3 4 5)) => '(9 1 2 3 4 5)
     (-replace-at 1 9 '(0 1 2 3 4 5)) => '(0 9 2 3 4 5)