Ruby 3 is shaping up nicely:

TypeProf

TypeProf is a type analysis tool bundled in the Ruby package.
Currently, TypeProf serves as a kind of type inference.

Ractor (experimental)

Ractor is an Actor-model like concurrent abstraction designed to provide a parallel execution feature without thread-safety concerns.

You can make multiple ractors and you can run them in parallel. Ractor enables you to make thread-safe parallel programs because ractors can not share normal objects. Communication between ractors are supported by message passing.

Fiber Scheduler

Fiber#scheduler is introduced for intercepting blocking operations. This allows for light-weight concurrency without changing existing code. Watch “Don’t Wait For Me, Scalable Concurrency for Ruby 3” for an overview of how it works.

Other Notable New Features

• One-line pattern matching is redesigned. (experimental)
• Find pattern is added. (experimental)
• Endless method definition is added.
• Hash#except is now built-in.
• Plus loads more

Wow!