Eloquent Ruby, Second Edition
by Russ Olsen · Pragmatic Bookshelf
Guide to writing idiomatic Ruby, updated for Ruby 3.4. It covers Ruby conventions for methods, classes, modules, collections and tests, then moves on to metaprogramming, domain-specific languages, and new chapters on pattern matching and concurrency. Covers the 'Ruby idioms' part of the topic note, which Rails-focused resources skip.
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