We are currently developing Lean 4 in a new (private) repository. The source code will be moved here when Lean 4 is ready. Users should not expect Lean 4 will be backward compatible with Lean 3.
- New compiler and C++ code generator.
- JIT compiler on top of LLVM.
- New runtime (support for unboxed values and FFI).
- New monad for accessing primitives that are currently available only in C++ (e.g.,
type_context
). - New parser and macro expander (in Lean).
- Make sure that tactics such as
simp
can be efficiently implemented in Lean. - Fix critical issues (e.g., issue #1601).
- Fix language issues (e.g., parameters, kernel enforced private declarations, kernel support for nested inductive datatypes).
- Reduce clutter in the core lib and code base.