Ruby

1. Literals

   Numbers, strings, symbols, arrays, hashes, ranges, regular expressions and heredocs.

2. Assignment and variables

   Local, instance, class and global variables, multiple assignment and destructuring.

3. Control expressions

   if, unless, case, while, until, for, loop controls and flip-flops.

4. Methods

   Method definition, arguments (default, keyword, splat), return values, visibility and method_missing.

5. Calling methods

   Receivers, arguments, blocks, safe navigation and message sending.

6. Blocks, procs and lambdas

   Blocks, yield, Proc and lambda semantics, closures and block arguments.

7. Modules and classes

   Class and module definitions, inheritance, mixins with include/extend/prepend, singleton classes.

8. Exceptions

   begin/rescue/ensure/retry, raise, custom exception classes.

9. Pattern matching

   case/in, deconstruct and deconstruct_keys, guards and find patterns.

10. Refinements

    Scoped monkey-patching with refine and using.

11. Operator precedence

    Operator precedence and associativity.

12. Enumerable and collections

    Enumerable, Enumerator, lazy enumeration, Array and Hash iteration.

13. Object model and metaprogramming

    Classes as objects, define_method, instance_variable_get, Module hooks and singleton methods.

14. Comparable and equality

    <=>, ==, eql?, equal? and hash for custom objects.

15. Threads, fibers and Ractors

    Threads, Mutex, the GVL, Fiber and Fiber scheduler, and Ractor.

16. IO and files

    File and IO classes, streams and path handling.

17. Keywords and standard library

    Official language documentation, getting started guides and standard library index.

Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.

Source: endoflife.date

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