# HG changeset patch
# User wenzelm
# Date 1631307827 -7200
# Node ID 1fc263b5aac1de9d33594623e31663d0816deb6f
# Parent  f79dfc7656ae18679b16f447c53b36a7c4d3dee1
NEWS;

diff -r f79dfc7656ae -r 1fc263b5aac1 NEWS
--- a/NEWS	Fri Sep 10 22:46:41 2021 +0200
+++ b/NEWS	Fri Sep 10 23:03:47 2021 +0200
@@ -248,6 +248,19 @@
 adoption; better use TVars.add, TVars.add_tfrees etc. for scalable
 accumulation of items.
 
+* The "build" combinators of various data structures help to build
+content from bottom-up, by applying an "add" function the "empty" value.
+For example:
+
+  - type 'a Symtab.table etc.: build
+  - Type 'a Names.table etc.: build
+  - type 'a list: build and build_rev
+  - type Buffer.T: build and build_content
+
+For example, see src/Pure/PIDE/xml.ML:
+
+  val content_of = Buffer.build_content o fold add_content;
+
 * ML antiquotations \<^try>\<open>expr\<close> and \<^can>\<open>expr\<close> operate directly on
 the given ML expression, in contrast to functions "try" and "can" that
 modify application of a function.