 Consider the factorial function F("n") recursively defined by

In the lambda expression which is to represent this function, a "parameter" (typically the first one) will be assumed to receive the lambda expression itself as its value, so that calling it – applying it to an argument – will amount to recursion.Thus to achieve recursion, the intended-as-self-referencing argument (called "r" here) must always be passed to itself within the function body, at a call point