v4.0.0

This is the first official release of Lean 4.

We intend to begin regular releases of Lean 4, providing a new "minor" version approximately monthly.
We do not yet make promises about backwards compatibility, although all breaking changes will be documented in RELEASES.md.

Please visit

• Our community forum on Zulip! This is the best place to get help, and find out what the Lean community is working on.
• The Lean language website for downloads and documentation.
• The homepage of the Lean Focused Research Organization for the team behind Lean.
• The Lean community website for help getting started, tutorials, and information about Mathlib.
• The Mathlib GitHub repository, for Lean's major mathematical library.

We have had over 2000 commits since the previous milestone.

% git log v4.0.0-m5..v4.0.0 --pretty="%an" | sort | uniq -c | sort -rn
 833 Leonardo de Moura
 662 Mac Malone
 301 Sebastian Ullrich
 228 Gabriel Ebner
 215 Mario Carneiro
  46 Henrik Böving
  41 Ed Ayers
  26 Scott Morrison
  20 Siddharth Bhat
  12 Wojciech Nawrocki
  11 Bulhwi Cha
   8 Adrien Champion
   7 Chris Lovett
   6 Alex J Best
   5 Yuri de Wit
   5 Tobias Grosser
   4 Rishikesh Vaishnav
   4 David Renshaw
   3 pcpthm
   3 int-y1
   3 Patrick Massot
   3 Martin Dvořák
   3 Marcus Rossel
   3 Elias Aebi
   2 Pietro Monticone
   2 Parth Shastri
   2 Joachim Breitner
   2 Jannis Limperg
   2 James Gallicchio
   2 François G. Dorais
   2 Floris van Doorn
   2 Eric Wieser
   2 Connor Baker
   2 Chris Hughes
   2 Anders Christiansen Sørby
   1 thorimur
   1 mcdoll
   1 locriacyber
   1 joao guilherme
   1 bc²
   1 awson
   1 ammkrn
   1 Richard Musiol
   1 Olivier Taïbi
   1 Matthias Hetzenberger
   1 Kaiyu Yang
   1 Junyan Xu
   1 Juan Pablo Romero
   1 Jon Eugster
   1 Jeremy Salwen
   1 Jakob von Raumer
   1 Gabriel Dahia
   1 Fynn Schmitt-Ulms
   1 Evgenia Karunus
   1 Enrico Borba
   1 Denis Gorbachev
   1 David Thrane Christiansen
   1 Arthur Paulino
   1 Andrés Goens