[Iris-Club] Iris 4.2 and std++ 1.10

[Ralf Jung]

Hi everyone,

We are happy to announce the release of Iris 4.2 and std++ 1.10. Iris is a 
concurrent separation logic framework for Coq; for an overview of the numerous 
research projects employing Iris, see https://iris-project.org/. std++ is an 
extended “standard” library for Coq.

The highlights of this new Iris version are:

* We have new laws to "undiscard" discarded fractions, allowing one to update 
from `DfracDiscarded` to `DfracOwn(q)` for some fresh `q`. This gives rise to 
new laws for all constructions that use `dfrac`, such as 
`ghost_map_elem_unpersist : ∀ k γ v, k ↪[γ]□ v ==∗ ∃ q, k ↪[γ]{#q} v`.
* The `gmap_view K V` camera now supports value types `V` that are arbitrary 
cameras, and lifts their composition to the whole map. The previous `gmap_view` 
type can be recovered as `gmap_view K (agree V)`.
* The `iFrame` tactic has become stronger for goals that contain existential 
quantifiers: `iFrame` will now attempt to instantiate these. For example, 
framing `P x` in goal `Q ∗ ∃ y, P y ∗ R` will now succeed with remaining goal `Q 
∗ R`.

For std++, the biggest new feature in this release is the bitvector library with 
support for fixed-size integers. It is distributed as a separate package, 
`coq-stdpp-bitvector`. The library is developed and maintained by Michael
Sammler.

The supported Coq versions are 8.18 and 8.19.

For further details, see the full changelog of Iris at 
https://gitlab.mpi-sws.org/iris/iris/-/blob/master/CHANGELOG.md#iris-420-2024-04-12 
and std++ at 
https://gitlab.mpi-sws.org/iris/stdpp/-/blob/master/CHANGELOG.md#std-1100-2024-04-12.

This release was managed by Ralf Jung and Robbert Krebbers.

std++ received further contributions from Mathias Adam Møller, Michael Sammler, 
Pierre Rousselin, Pierre Roux, and Thibaut Pérami.

Iris received further contributions from Ike Mulder, Jan-Oliver Kaiser, Johannes 
Hostert, Pierre Roux, Thomas Somers, and Yixuan Chen.

Thanks a lot to everyone involved!

Both packages are available in the Coq opam registry. For further information 
and installation instructions for Iris and std++, see the respective project 
websites:
* https://gitlab.mpi-sws.org/iris/iris
* https://gitlab.mpi-sws.org/iris/stdpp

If you have any questions, feel free to reply to this email, or join our Iris 
community chat room: https://iris-project.org/chat.html.

Best,
The Iris and std++ teams