Shopify-built YJIT compiler promises to bring faster warmup and higher performance to Ruby on Rails apps. Credit: Thinkstock Ruby, the popular dynamic programming language that is now more than a quarter-century old, is set to add a performance-boosting, just-in-time compiler with the planned 3.1.0 version. Now in an initial preview as of November 9, Ruby 3.1.0 is downloadable from the project website. Ruby 3.1.0 integrates YJIT (Yet Another Ruby JIT), an in-process JIT compiler developed by Shopify. YJIT still is an experimental feature. The developers of Ruby describe YJIT as an important contribution that is intended to improve Ruby on Rails application performance. YJIT is a basic block versioning JIT compiler that achieves both fast warmup and performance improvements on most real-world software, a ruby-lang.org blog post said. YJIT is disabled by default at this stage. Developers who want to enable it it must specify the --yjit command-line option. YJIT is currently limited to MacOS and Linux on x86-64 platforms. Also in Ruby 3.1.0: The debug.gem debugger replaces the lib/debug.rb standard library, promising faster debugging and capabilities such as remote debugging, colorful REPL and Visual Studio Code. A built-in gem, error_highlight, brings fine-grained error location in backtrace. For the language itself, values in Hash literals and keyword arguments can be omitted. The pin operator in pattern matching now takes an expression. Updates to the RBS language for describing the structure of Ruby programs include rbs collection, to manage gems’ RBSs, and updates and additions to signatures for built-in and standard libraries. Bug fixes and performance improvements also have been made to RBS. The TypeProf static type analyzer has been updated with experimental IDE support as well as bug fixes and performance improvements. Performance of the MJIT compiler has been improved. Ruby 3.0.0, featuring parallel execution, arrived last Christmas. RubyProgramming LanguagesSoftware Development