NEWS for Ruby 3.1.0

This document is a list of user visible feature changes since the 3.0.0 release, except for bug fixes.

Note that each entry is kept to a minimum, see links for details.

Language changes

Command line options

Core classes updates

Outstanding ones only.

Enumerable
- Enumerable#compact is added. [Feature #17312]
Enumerator::Lazy
- Enumerator::Lazy#compact is added. [Feature #17312]
Module
- Module#prepend now modifies the ancestor chain if the receiver already includes the argument. Module#prepend still does not modify the ancestor chain if the receiver has already prepended the argument. [Bug #17423]
Struct
- Passing only keyword arguments to Struct#initialize is warned. You need to use a Hash literal to set a Hash to a first member. [Feature #16806]

Stdlib updates

Outstanding ones only.

Compatibility issues

Excluding feature bug fixes.

Stdlib compatibility issues

ERB#initialize warns safe_level and later arguments even without -w. [Feature #14256]

C API updates

Implementation improvements

JIT

RubyVM::MJIT is renamed to RubyVM::JIT.

Static analysis

RBS

TypeProf

Miscellaneous changes