Well, not show, because any show instance for functions breaks r.t.  But the interactive interpreter, if it is not subject to r.t., might show:

let { f x = g x;

      g 0 = 0;

      g n = f (n-1) } in f

Or

fst (fix (\~(f,g) -> (\x -> g x, \n -> case n of { 0 -> 0; n -> f (n-1) })))

Or any number of other equivalent writings.

Luke