Ruby 2.7 improves garbage collection, pattern matching

Ruby upgrade also includes enhancements to the REPL and an experimental just-in-time compiler

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Ruby on Rails 6.0 adds rich text capabilities. Photo: Aleksey Nemiro

7 January 2020

Ruby 2.7, the latest upgrade of the Ruby programming language, is now generally available as a production release. The new release brings improvements in garbage collection, pattern matching, and REPL (read-eval-print-loop).

New in the Ruby 2.7 is compaction garbage collection, which is used to defragment a fragmented memory space. The GC.compact method compacts the objects in the heap so that fewer pages are used. Members of the Ruby development team explained that some multi-threaded Ruby programs may cause memory fragmentation, which leads to high memory utilisation and speed degradation.

Other improvements in Ruby 2.7.0 include:

An experimental pattern matching capability, which can traverse a given object and assign a value if it matches a pattern. Pattern matching is widely used in functional programming languages.
Multi-line editing is now supported in irb, the interactive Ruby shell. Integration with rdoc, the Ruby documentation system, also is provided. With irb, developers can display the reference for a class, method, or module. Also, source lines shown at binding.irb and inspect results for core-class objects now are colourised.
Automatic conversion of keyword and positional arguments has been deprecated. This feature will be removed in Ruby 3.
For the still-experimental just-in-time (JIT) compiler, first introduced in Ruby 2.6, JIT-ed code is recompiled to less-optimized code when an optimization has been invalidated. Further, method inlining is performed when a method is considered pure. However, many methods are not yet considered pure.
An Enumerable#tally counts the occurrence of each element.
Also introduced is a numbered parameter as the default block parameter.

You can download Ruby 2.7 from ruby-lang.org.

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