逻辑表达式
let true = \a.\b.a
let false = \a.\b.b
let not = \x.x false true
let and = \x.\y. x y false
let or = \x.\y. x true y
let xor = \x.\y.x (not y) y
逻辑表达式
let true = \a.\b.a
let false = \a.\b.b
let not = \x.x false true
let and = \x.\y. x y false
let or = \x.\y. x true y
let xor = \x.\y.x (not y) y