Ruby
· Dynamic reflection and alteration of objects to facilitate metaprogramming
· Lexical closures, iterators and generators, with a unique block syntax
· Literal notation for arrays, hashes, regular expressions and symbols
· Embedding code in strings (interpolation)
· Default arguments
· Four levels of variable scope (global, class, instance, and local) denoted by sigils or the lack thereof
· Garbage collection
· First-class continuations
· Strict boolean coercion rules (everything is true except false and nil)
· Exception handling
· Operator overloading
· Built-in support for rational numbers, complex numbers and arbitrary-precision arithmetic
· Custom dispatch behavior (through method_missing and const_missing)
· Native threads and cooperative fibers
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