This strict version of Y works with a strict interpreter (the lazy one will not). You can program this Y in many conventional languages such as Algol-68.

let F = lambda f. lambda n. if n=0 then 1 else n*f(n-1),

    Y = lambda G.
        let Ggg = lambda g. lambda n. G(g g)n
        in  Ggg Ggg

in Y F 10

{\fB Strict Version of Y. \fP}