Ruby language upgrade improves garbage collection, pattern matching

Preview release of Ruby 2.7 also includes enhancements to the REPL and an experimental just-in-time compiler

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

The general release is planned for December 2019. New in the Ruby preview release 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 utilization 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 colorized.
  • 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.
  • A method reference operator, .:, is included on an experimental basis.
  • Also introduced as an experimental feature is a numbered parameter as the default block parameter.

You can download the preview release of Ruby 2.7 as well as stable releases of Ruby from