(VAR x xs y ys z )
(RULES 
        le(s(x), 0) -> false
        le(0, y) -> true
        le(s(x), s(y)) -> le(x, y)
        double(0) -> 0
        double(s(x)) -> s(s(double(x)))
        log(0) -> logError
        log(s(x)) -> loop(s(x), s(0), 0)
        loop(x, s(y), z) -> if(le(x, s(y)), x, s(y), z)
        if(true, x, y, z) -> z
        if(false, x, y, z) -> loop(x, double(y), s(z))
        maplog(xs) -> mapIter(xs, nil)
        mapIter(xs, ys) -> ifmap(isempty(xs), xs, ys)
        ifmap(true, xs, ys) -> ys
        ifmap(false, xs, ys) -> mapIter(droplast(xs), cons(log(last(xs)), ys))
        isempty(nil) -> true
        isempty(cons(x, xs)) -> false
        last(nil) -> error
        last(cons(x, nil)) -> x
        last(cons(x, cons(y, xs))) -> last(cons(y, xs))
        droplast(nil) -> nil
        droplast(cons(x, nil)) -> nil
        droplast(cons(x, cons(y, xs))) -> cons(x, droplast(cons(y, xs)))
        a -> b
        a -> c
        
)