- fun add (x,y) = x + y;

- fun addR (x : real, y : real) = x + y;

- fun count x = if null(x) then 0
                else 1 + count(tl(x));

- fun count ([]) = 0
       | count(h::t) = 1 + count(t);

- fun append(x,z) = if null(x) then z
                    else hd(x)::append(tl(x),z);

- fun append ([], z) = z
      | append (h::t,z) = h::append(t,z);

- fun member(x,[]) = false
      | member(x,b::y) = if x=b then true else member(x,y);

- fun int ([],l1) = [] |
      int (h::l1,l2) = if member(h,l2) then h:: int(l1,l2)
                                       else int(l1,l2);

- fun gcd (u,v) = if v = 0 then u else gcd(v, u mod v);

- fun gcd u v = if v = 0 then u else gcd v (u mod v);

- fun map f [] = []
         | map f (h::t) = f(h):: map f t;