Indeed, there is a backward compatibility mode declaration. In fixing things, I've been trying to use it as little as possible and as locally as possible. Perhaps I should be bolder.

I'm aesthetically against using the compatibility mode all over the place, since I feel that it's just mysterious. Of course, a lot of Isabelle proof scripts are a bit mysterious already.

In particular, I want to avoid ever changing the setting globally. I've had some bad experiences in the past with theories with differing global configurations, which means that the location of a tactic and the include graphs of theories start having subtle effects on the way the tactics run. It's a mess.

I've started running through the AFP, and it doesn't look too bad. I'll report on this again in the next few days.

Cheers all,

On 04/06/14 23:23, Lawrence Paulson wrote:
Didn’t we agree that a “backward compatibility mode” declaration (restoring the 
former behaviour) would have to be available? That should make repairing legacy 
proofs trivial. Naturally we would like to gradually port some of these 
developments to do things the new way, but only some of them, and not 

Backward compatibility will be necessary for users, even if not for us.


On 4 Jun 2014, at 06:27, Thomas Sewell <> wrote:

I had hoped to have the change I was making to hypothesis-substitution ready 
for the coming release.

I've got it working for all of HOL and the library, and begun looking at the 
AFP and at the l4.verified proofs. The HOL+library changes were easy enough, 
but the l4.verified changes are somewhat daunting and I haven't gotten anywhere 
with the AFP yet.

I'll have another look at it, because I'd like this to go somewhere at some 
point. It might have to wait for a subsequent release though.


On 30/05/14 21:30, Makarius wrote:
The summer is getting close, and we need to start thinking about the coming 

I am myself on vacation during most of June. On return I would like to wrap up 
rather quickly, so that we can publish Isabelle2014-RC0 in the second week of 
July, for the Isabelle tutorial at VSL2014 Vienna.  That will be still within 
the main Isabelle repository.

The usual fork to the release repository and the regular sequence of 
Isabelle2014-RC1, RC2, RC3, ... will happen in the week after ITP 2014.

I am myself attending the mega event at Vienna 13..19-Jul-2014. This will be 
also an opportunity to show me personally remaining snags, and to continue the 
elimination of remaining uses of Proof General.  (It is getting harder and 
harder to construct counter-examples to the claim that this set is already 

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