From 2ea3dc4db81e6513810da086a65f9c8292d4bebf Mon Sep 17 00:00:00 2001
From: letouzey
Date: Sat, 7 Jul 2007 14:53:20 +0000
Subject: If a fixpoint is not written with an explicit { struct ... }, then
 all arguments are tried successively (from left to right) until one is found
 that satisfies the structural decreasing condition.

When the system accepts a fixpoint, it now prints which decreasing argument 
was used, e.g:

 plus is recursively defined (decreasing on 1st argument)

The search is quite brute-force, and may need to be optimized for huge mutual
fixpoints (?). Anyway, writing explicit {struct} is always a possible fallback.

N.B. in the standard library, only 4 functions have an decreasing argument 
different from the one that would be automatically infered: 
  List.nth, List.nth_ok, List.nth_error, FMapPositive.xfind
And compiling with as few explicit struct as possible would add about 15s 
in compilation time for the whole standard library. 




git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@9961 85f007b7-540e-0410-9357-904b9bb8a0f7
---
 CHANGES | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'CHANGES')

diff --git a/CHANGES b/CHANGES
index 7917e72953..efbe41c5eb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,12 @@
 Changes from V8.1 to V8.2
 =========================
 
+Language 
+
+- If a fixpoint is not written with an explicit { struct ... }, then 
+  all arguments are tried successively (from left to right) until one is 
+  found that satisfies the structural decreasing condition.
+
 Commands
 
 - Added option Global to "Implicit Arguments" and "Arguments Scope" for
-- 
cgit v1.2.3