What's new in Ruby 3.2 (2024)

Ruby 3.2 was released on Christmas day,and I’ve been playing around with its new features.The highlights this year arethe performance gains from YJIT,WebAssembly support,faster regular expressions,and a new way to define immutable value objects,

(This is only a list of thingsI found most interesting about this release.If you’re looking for a more complete list,take a look at therelease announcement.)

YJIT is now production ready (and really fast!)

YJIT, the new JIT compiler for Ruby,was released last yearas an experimental feature.Now it’s been marked production ready,and brings even more performance gains.Here are a couple of readsabout real world performance gains:

• Uf*ck Kayserilioglu has writtenabout deploying a prerelease version of Ruby 3.2 with YJITto render Shopify storefronts,and seeing 10% speedups.
• Peter Solnica has benchmarkedthe dry-rb libraries,and had some impressive numbers to share there.

YJIT was alsocompletely rewritten in Rustin order to make it easier to maintain.This allowed the teamto quickly add support for ARM.This means that you can now run YJITon your M-series macsor a Raspberry Pi.

Immutable objects with Data.define

The newly introduced Data classallows you to defineimmutable value objects.

# Create a Point data classPoint = Data.define(:x, :y)# Instantiate a point objectp = Point.new(x: 3, y: 7)

This might seem familiarbecause we already have Struct.newwhich defines similar classes.However, Data classes are immutable,so don’t have setters for the attributes.

point.x = 42#=> undefined method `x=' for #<data Point x=3, y=7> (NoMethodError)

Data also defines the deconstruct and deconstruct_keys methodsso that the objects can be pattern matched like this:

case pointin Point(0, 0) puts "Origin"in Point(x, y) if x + y > 10 puts "Too far away"in Point(x, y) puts "(#{x}, #{y})"end

Struct with keyword args

There’s a small usability improvement with structs as well.The keyword_init: true argument is no longer neededto initialize structs with keyword args.

# Ruby 3.1Point = Struct.new(:x, :y, keyword_init: true)# Ruby 3.2Point = Struct.new(:x, :y)Point.new(x: 2, y: 3)#=> #<struct Point x=2, y=3>

Regular expressions

There are improvements to Regex,mainly to prevent ReDOS (regexp denial-of-service) attacks.Firstly, the regexp matching algorithm has been improvedso that many matches will complete in linear time.For regexes that can’t use this optimization,you can also set a timeoutso that a Regexp::TimeoutError is raisedif the match exceeds that time.

# Set a 2s timeout for a single regexpattern = Regexp.new(/foo/, timeout: 2)"foo".match(pattern)# Or set a global timeoutRegexp.timeout = 5

IRB

One of my favorite things about recent releases of Rubyis the focus on tools like IRB.Ruby 3.2 bundles the latest version 1.6 of IRB.This brings support for a lot of the debugging commandsthat you might have seen in gems like pry and byebug.Stan Lo, who worked on many of these featureshas written in detail aboutthe new features of IRB.

As someone who has always usedpry and pry-byebug,I’m excited about these changes.We will be able to get most of the benefitsof those toolsout of the box with Ruby.

Better error messages

syntax_suggest has been integrated into Ruby,and points out missing or extra ends in your code.This functionality was previously in a gemcalled dead_end,but it was merged into Ruby itself.

Unmatched `end', missing keyword (`do', `def`, `if`, etc.) ?> 2 def foo> 4 end> 5 endtest.rb:5: syntax error, unexpected `end' (SyntaxError)

The builtin error_highlight gemnow highlights the relevant argumentfor TypeError and ArgumentError.

test.rb:3:in `+': nil can't be coerced into Integer (TypeError)bar = 1 + foo[5] ^^^^^^ from test.rb:3:in `<main>'

WebAssembly support

Ruby now supports WebAssembly,which means that Ruby can now run in browsers!You can already see this in action in the Try Ruby playground.Another example isRuby Syntax Tree,which converts Ruby code into s-expressions.(Kevin Newton has written more about ithere).

Other changes

• Set is now a builtin class,and you no longer needto require "set" to use it.
• bundle gem now supports --ext=rustto allow building gems with rust extensions.(details here)

Further reading

With these posts,I try to highlight some of the changesthat I found most interesting,and often skip over features I might not use.If you’re looking for a more comprehensive look at the release,I highly recommend looking at therelease announcement,changelog,and the excellentRuby References website,which covers all the new features in detail with lots of examples.

Other links

• Year in Review 2022: Tenderlove’s Ruby and Rails Reflections and Predictions
• It is not what you expect, but it is what you want: how Data#initialize is designed