Global assignments are made using set and the values of the variables recovered using value.
(1-) (set dozen 6) 6 (2-) dozen dozen (3-) (value dozen) 6 (4-) (bound? dozen) true
Local assignments are made using let. let takes three arguments, a variable v, an expression e1 and an expression e2 and binds v to the normal form of e1 in the evaluation of e1.
let is polyadic; (let X1 a1 .... Xn an) is short for (let X1 a1 .... (let Xn an)...).
(5-) (let X 6 Y 5 (* X Y)) 30
See also property lists.