Ruby 3.2.0 Preview 1 Released

We are pleased to announce the release of Ruby 3.2.0-preview1. Ruby 3.2 adds many features and performance improvements.

WASI based WebAssembly support

This is an initial port of WASI based WebAssembly support. This enables a CRuby binary to be available on Web browser, Serverless Edge environment, and other WebAssembly/WASI embedders. Currently this port passes basic and bootstrap test suites not using Thread API.


WebAssembly (WASM) is originally introduced to run programs safely and fast in web browsers. But its objective - running programs efficiently with security on various environment - is long wanted not only by web but also by general applications.

WASI (The WebAssembly System Interface) is designed for such use cases. Though such applications need to communicate with operating systems, WebAssembly runs on a virtual machine which didn’t have a system interface. WASI standardizes it.

WebAssembly/WASI Support in Ruby intends to leverage those projects. It enables Ruby developers to write applications which runs on such promised platform.

Use case

This support enables developers to utilize CRuby in a WebAssembly environment. An example use case is TryRuby playground’s CRuby support. Now you can try original CRuby in your web browser.

Technical points

Today’s WASI and WebAssembly itself has some missing features to implement Fiber, exception, and GC because it’s still evolving and also for security reasons. So CRuby fills the gap by using Asyncify, which is a binary transformation technique to control execution in userland.

In addition, we built a VFS on top of WASI so that we can easily pack Ruby apps into a single .wasm file. This makes distribution of Ruby apps a bit easier.

Related links

Regexp timeout

A timeout feature for Regexp matching is introduced.

Regexp.timeout = 1.0

/^a*b?a*$/ =~ "a" * 50000 + "x"
#=> Regexp::TimeoutError is raised in one second

It is known that Regexp matching may take unexpectedly long. If your code attempts to match an possibly inefficient Regexp against an untrusted input, an attacker may exploit it for efficient Denial of Service (so-called Regular expression DoS, or ReDoS).

The risk of DoS can be prevented or significantly mitigated by configuring Regexp.timeout according to the requirements of your Ruby application. Please try it out in your application and welcome your feedback.

Note that Regexp.timeout is a global configuration. If you want to use different timeout settings for some special Regexps, you may want to use timeout keyword for

Regexp.timeout = 1.0

# This regexp has no timeout
long_time_re ="^a*b?a*$", timeout: nil)

long_time_re =~ "a" * 50000 + "x" # never interrupted

The original proposal is

Other Notable New Features

No longer bundle 3rd party sources

  • We no longer bundle 3rd party sources like libyaml, libffi.

    • libyaml source has been removed from psych. You may need to install libyaml-dev with Ubuntu/Debian platform. The package name may differ on other platforms.

    • libffi will be removed from fiddle at preview2


  • Find pattern is no longer experimental.

Performance improvements

Other notable changes since 3.1

  • Hash
    • Hash#shift now always returns nil if the hash is empty, instead of returning the default value or calling the default proc. [[Bug #16908]]
  • MatchData
    • MatchData#byteoffset has been added. [[Feature #13110]]
  • Module
    • Module.used_refinements has been added. [[Feature #14332]]
    • Module#refinements has been added. [[Feature #12737]]
    • Module#const_added has been added. [[Feature #17881]]
  • Proc
    • Proc#dup returns an instance of subclass. [[Bug #17545]]
    • Proc#parameters now accepts lambda keyword. [[Feature #15357]]
  • Refinement
    • Refinement#refined_class has been added. [[Feature #12737]]
  • Set
    • Set is now available as a builtin class without the need for require "set". [[Feature #16989]] It is currently autoloaded via the Set constant or a call to Enumerable#to_set.
  • String
    • String#byteindex and String#byterindex have been added. [[Feature #13110]]
    • Update Unicode to Version 14.0.0 and Emoji Version 14.0. [[Feature #18037]] (also applies to Regexp)
    • String#bytesplice has been added. [[Feature #18598]]
  • Struct
    • A Struct class can also be initialized with keyword arguments without keyword_init: true on [[Feature #16806]]

Standard libraries updates

  • The following default gem are updated.

    • TBD
  • The following bundled gems are updated.

    • TBD
  • The following default gems are now bundled gems. You need to add the following libraries to Gemfile under the bundler environment.

    • TBD

See NEWS or commit logs for more details.

With those changes, 1058 files changed, 34946 insertions(+), 29962 deletions(-) since Ruby 3.1.0!



    SIZE: 20728782
    SHA1: 7c4197e67f230b0c5d011f4efb9b9158743a61c8
    SHA256: 6946b966c561d5dfc2a662b88e8211be30bfffc7bb2f37ce3cc62d6c46a0b818
    SHA512: d24e77161996c2085f613a86d1ed5ef5c5bf0e18eb459f6a93a0014a5d2ce41079283b4283d24cb96448a0986c8c6c52a04584abd4e73911ea59cefeb786836e

    SIZE: 15011400
    SHA1: 6bcc30ac670ab391997e0d68ba97b451db078934
    SHA256: 6d28477f7fa626b63bf139afd37bcfeb28fce6847b203fa10f37cb3615d0c35d
    SHA512: 0eca2c346b995d265df2659b4215ff96e515c29926c2a6256caad99db9c4c51fec1a2d899ca63a00010d4111060dc0fdd4f591be84c0a2c43b6303879de3c5de

    SIZE: 25370458
    SHA1: 3c93c2e775366eec6e93cf670fc8677934cb4e48
    SHA256: 24f8ae73d56366453defb0654de624bd1c063921a1d7ac780e4da56bb8fbf7e4
    SHA512: 9754f11aa167df167d1b336e5c660aab1bd9e12421c093e0fe96e9a2da4ffb9859b7ea5263473bbc7b57ac8b5568cf7ac3116c0abdc647e1ff97a8d060ff7eae

What is Ruby

Ruby was first developed by Matz (Yukihiro Matsumoto) in 1993, and is now developed as Open Source. It runs on multiple platforms and is used all over the world especially for web development.