[ruby-core:72045] Ruby 2.3.0-preview2 Released

["NARUSE, Yui" <naruse@airemix.jp>]

We are pleased to announce the release of Ruby 2.3.0-preview2.

Ruby 2.3.0-preview2 is the second preview of Ruby 2.3.0.
Many new features and improvements are included.

A [Frozen String Literal Pragma](https://bugs.ruby-lang.org/issues/11473)
is introduced.
With Ruby 2.1, `"str".freeze` has been optimized to reduce object allocation.
Ruby 2.3 introduces a new magic comment and command line option to
freeze all string literals in the source files.
Additionally for debugging, you can get where the object is created on
`"can't modify frozen String"` error by
`--debug=frozen-string-literal` command line option.

A [safe navigation operator](https://bugs.ruby-lang.org/issues/11537)
([so-called lonely operator](https://instagram.com/p/-M9l6mRPLR/)) `&.`,
which already exists in C#, Groovy, and Swift, is introduced to ease
`nil` handling as `obj&.foo`. `Array#dig` and `Hash#dig` are also added.

The [did_you_mean gem is bundled](https://bugs.ruby-lang.org/issues/11252).
The did_you_mean gem
shows the candidates on the `NameError` and `NoMethodError` to ease
debugging.

[RubyVM::InstructionSequence#to_binary and .load_from_binary]
(https://bugs.ruby-lang.org/issues/11788) are introduced as
experimental feature. With these features, we can make a ISeq
(bytecode) pre-compilation system.

Ruby 2.3 includes many performance tuning fixes.
For example, [optimize Proc#call] (https://bugs.ruby-lang.org/issues/11569),
[reconsider method entry data structure]
(https://bugs.ruby-lang.org/issues/11278),
[introducing new table data structure]
(https://bugs.ruby-lang.org/issues/11420),
machine code level tuning for object allocation and method calling code,
and other many optimizations.

Try and enjoy programming with Ruby 2.3.0-preview2, and report us your
knowledge!

## Notable Changes since 2.2

See [NEWS](https://github.com/ruby/ruby/blob/v2_3_0_preview2/NEWS) and
[ChangeLog](https://github.com/ruby/ruby/blob/v2_3_0_preview2/ChangeLog)
for detail.

With those changes, [1097 files changed, 97466 insertions(+), 58685
deletions(-)](https://github.com/ruby/ruby/compare/v2_2_0...v2_3_0_preview2)
since Ruby 2.2.0!

## Download

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* <https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.0-preview2.tar.gz>
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* <https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.0-preview2.tar.xz>
  * SIZE:   11249780 bytes
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* <https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.0-preview2.zip>
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## Release Comment

See also the release schedule and other information:

[ReleaseEngineering23](https://bugs.ruby-lang.org/projects/ruby-trunk/wiki/ReleaseEngineering23)


-- 
NARUSE, Yui  <naruse@airemix.jp>