news: new syntax (%gprec and %precr)
diff --git a/NEWS b/NEWS
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+++ b/NEWS
@@ -2,6 +2,32 @@
* Noteworthy changes in release ?.? (????-??-??) [?]
+** New syntax: partial-order precedence relationships
+
+ Formerly, the precedence order of tokens was linear, depending only on the
+ order in which they were declared. With the new syntax, all the tokens are
+ not necessarily comparable. It is possible to declare a group of tokens with
+ no links outside of the group, and to later on add only those needed.
+ The uncomparability of tokens would allow for more feedback on new conflicts
+ silently resolved via precedence.
+
+ An example of the new syntax applied to arithmetic and boolean operators,
+ with '^' serving as both numerical power and boolean XOR:
+
+ %gprec arith {
+ %left '+' '-'
+ %left '*' '/'
+ }
+ %gprec bool {
+ %left OR
+ %left AND
+ }
+ %gprec { %right '^' }
+
+ %precr '^' > arith
+ %precr OR AND > '^'
+
+ Here, AND is not comparable with '+', but '^' > '+' and AND > '^'
* Noteworthy changes in release 3.0 (2013-07-25) [stable]
