org-list: Implement `org-list-to-org'

* lisp/org-list.el (org-list-to-org): New function.
* testing/lisp/test-org-list.el (test-org-list/to-org): New test.

etc/ORG-NEWS

@@ -120,6 +120,13 @@ narrowed to current buffer to achieve a similar functionality.
 For an equivalent to a ~nil~ value, set
 ~org-agenda-show-future-repeats~ to nil and
 ~org-agenda-prefer-last-repeat~ to ~t~.
+
+** New functions
+
+*** ~org-list-to-org~
+
+It is the reciprocal of ~org-list-to-lisp~, which see.
+
 * Version 9.0
 
 ** Incompatible changes

lisp/org-list.el

@@ -3555,6 +3555,25 @@ PARAMS is a property list with overruling parameters for
   (require 'ox-texinfo)
   (org-list-to-generic list (org-combine-plists '(:backend texinfo) params)))
 
+(defun org-list-to-org (list &optional params)
+  "Convert LIST into an Org plain list.
+LIST is as returned by `org-list-parse-list'.  PARAMS is a property list
+with overruling parameters for `org-list-to-generic'."
+  (let* ((make-item
+	  (lambda (type _depth &optional c)
+	    (concat (if (eq type 'ordered) "1. " "- ")
+		    (and c (format "[@%d] " c)))))
+	 (defaults
+	   (list :istart make-item
+		 :icount make-item
+		 :ifmt (lambda (_type contents)
+			 (replace-regexp-in-string "\n" "\n  " contents))
+		 :dtend " :: "
+		 :cbon "[X] "
+		 :cboff "[ ] "
+		 :cbtrans "[-] ")))
+    (org-list-to-generic list (org-combine-plists defaults params))))
+
 (defun org-list-to-subtree (list &optional params)
   "Convert LIST into an Org subtree.
 LIST is as returned by `org-list-to-lisp'.  PARAMS is a property

testing/lisp/test-org-list.el

@@ -1326,6 +1326,39 @@
 		    (skip-chars-backward " \r\t\n")
 		    (point)))))))
 
+(ert-deftest test-org-list/to-org ()
+  "Test `org-list-to-org' specifications."
+  ;; Un-ordered list.
+  (should
+   (equal "- a"
+	  (org-test-with-temp-text "- a"
+	    (org-list-to-org (org-list-to-lisp) nil))))
+  ;; Ordered list.
+  (should
+   (equal "1. a"
+	  (org-test-with-temp-text "1. a"
+	    (org-list-to-org (org-list-to-lisp) nil))))
+  ;; Descriptive list.
+  (should
+   (equal "- a :: b"
+	  (org-test-with-temp-text "- a :: b"
+	    (org-list-to-org (org-list-to-lisp) nil))))
+  ;; Nested list.
+  (should
+   (equal "- a\n  - b"
+	  (org-test-with-temp-text "- a\n  - b"
+	    (org-list-to-org (org-list-to-lisp) nil))))
+  ;; Item spanning over multiple lines.
+  (should
+   (equal "- a\n  b"
+	  (org-test-with-temp-text "- a\n  b"
+	    (org-list-to-org (org-list-to-lisp) nil))))
+  ;; Item with continuation text after a sub-list.
+  (should
+   (equal "- a\n  - b\n  c"
+	  (org-test-with-temp-text "- a\n  - b\n  c"
+	    (org-list-to-org (org-list-to-lisp) nil)))))
+
 
 (provide 'test-org-list)
 ;;; test-org-list.el ends here