A fixed point combinator (or fixpoint combinator[1] ) is a higher-order function that computes a fixed point of other functions. A fixed point of a function f i

A fixed point combinator (or fixpoint combinator[1] ) is a higher-order function that computes a fixed point of other functions. A fixed point of a function f is a value x such that f(x) = x. For example, 0 and 1 are fixed points of the function f(x) = x2, because 02 = 0 and 12 = 1. Whereas a fixed-point of a first-order function (a function on "simple" values such as integers) is a first-order value, a fixed point of a higher-order function f is another function p such that f(p) = p. A fixed point combinator, then, is a function g which produces such a fixed point p for any function f: p = g(f), f(p) = p or, alternatively: f(g(f)) = g(f). http://en.wikipedia.org/wiki/Fixed_point_combinator http://en.wikipedia.org/wiki/Fixed_point_combinator