From the book Crafting Interpreters by Robert Nystrom.

• pylox: tree-walk interpreter
• clox: bytecode virtual machine

• REPL print value evaluated by expression
• break and continue in while & for loop
• Ternary operator
• Anonymous function / lambda

• Extend comparison between strings, using lexicographical order
• Operator + do concat when either operand is string OR support string interpolation
• REPL with readline support
• Traits for multi-inheritance

• Native function: hasField getField setField deleteField
  • Signal runtime error from native function
• General data structures: list/array, map/dictionary
  • Alternatively, implement fixed-size array as the only native data structure, then implement others on top of it
• Read/write to file
  • text file
  • binary file