variables type inference constants symbols strings string interpolation tuples named tuples ranges nilable types

if unless case while until each times loop do break next begin rescue ensure

method definitions default arguments named arguments splat arguments double splat blocks yield block forwarding overloads macros vs methods

classes structs modules enums abstract classes inheritance include extend properties class variables

Array Hash Set Deque Iterator Enumerable map select compact_map group_by sort_by

generic classes generic methods typeof is_a? narrowing case type narrowing macro macro for loops annotations compile-time run verbatim macro

spawn Fiber Channel buffered channel select sleep Mutex WaitGroup pattern HTTP server concurrency fiber exception handling

File.read File.write IO.copy JSON serialization YAML parsing HTTP client HTTP server command execution spec tests shards dependencies