Moreover, LAMBDA is the true lambda that we know and love: a lambda can be an argument to another lambda or its result; you can define the Church numerals; lambdas can return lambdas, so you can do currying; you can define a fixed-point combinator using LAMBDA and hence write recursive functions; and so on. (Additionally, since lambdas can be named, they can directly call themselves recursively, which is much more convenient than using a fixed-point combinator.)