"The reactive model we use is known as object-oriented reactive programming (using a 'push' model), which is both simple to understand and close to spreadsheet'

"The reactive model we use is known as object-oriented reactive programming (using a 'push' model), which is both simple to understand and close to spreadsheet's model (i.e. Excel formulas)." That they've managed to make this work in the language as a whole and not just the GUI is quite wonderful!