• Type Inference
• Builtin Literals for lists, hashes, arrays, regular expressions and timespans
• Slicing
• String Interpolation
• [Statement Modifiers]
• [Syntactic Attributes]
• Syntactic Macros
• Generators
  • Generator Expressions
  • List Generators
  • [Array Generators]
  • Generator Methods
• First Class Functions
  • Functions As Objects
• Closures
• Callable Types
• Duck Typing
• Extensible Compilation Pipeline
• [User-defined Value Types]
• Interactive Interpreter

See the Boo Language Guide for a more complete reference, as well as the Tutorials and Cookbook.