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

In F#, a little verbosily:

let x = ref 10
let y = ref 20

let z () = !x + !y

z();;
y <- 40
z();;