kunishi

datatype ('label) tree = 
  Node of 'label * 'label tree list;

fun sum(Node(a, nil)) = a
  | sum(Node(a, t::ts)) = sum(t) + sum(Node(a, ts));

kunishi

fun sumPairs(nil) = 0
|   sumPairs((x,y)::zs) = x + y + sumPairs(zs);

kunishi

fun sumLists(nil) = 0
|   sumLists(nil::YS) = sumLists(YS)
|   sumLists((x::xs)::YS) = x + sumLists(xs::YS);

kunishi

fun sumEach(nil) = (0, 0)
  | sumEach((x, y)::xs) =
    let
      val (s1, s2) = sumEach(xs)
    in
      (x + s1, y + s2)
    end;

kunishi

datatype 'label btree =
    Empty |
    Node of 'label * 'label btree * 'label btree;

fun sumBinTree(Empty) = 0
  | sumBinTree(Node(a, left, right)) =
    a + sumBinTree(left) + sumBinTree(right);

kunishi

fun memq(x, nil) = false
  | memq(x, y::ys) = 
    if x = y then true
    else memq(x, ys);

fun subset(nil, ys) = true
  | subset(x::xs, ys) = 
    if memq(x, ys) = false
	then false
    else subset(xs, ys);

kunishi

fun square(0) = 0
|   square(n) = square(n-1) + 2 * n - 1;

kunishi

fun split(nil) = (nil, nil)
|   split([a]) = ([a], nil)
|   split(a::b::cs) =
	let
	    val (M, N) = split(cs)
	in
	    (a::M, b::N)
	end;

kunishi

fun smult(nil, q) = nil
|   smult((p:real)::ps, q) = (p*q)::smult(ps, q);

kunishi

fun rotate(L) =
    if L=nil then nil
    else tl(L) @ [hd(L)];