Truly declarative language?

Question

Does anyone know of a truly declarative language? The behavior I\'m looking for is kind of what Excel does, where I can define variables and formulas, and have the formula\'s re

Answer 1

This F# code should do the trick. You can use lazy evaluation (System.Lazy object) to ensure your expression will be evaluated when actually needed, not sooner.

let mutable x = 10;
let y = 20;

let z = lazy (x + y);
x <- 30;

printf "%d" z.Value