get "libhdr"

let sudan(n, x, y) =
    n = 0 -> x + y,
    y = 0 -> x,
    sudan(n-1, sudan(n, x, y-1), sudan(n, x, y-1)+y)

let showtable(f, n, x, y) be
$(  writef("sudan(%N,x,y)*N", n)
    writes("     ")
    for i=0 to x do writed(i, 5)
    for i=0 to y
    $(  writef("*N%I4:", i)
        for j=0 to x do writed(f(n, j, i), 5)
    $)
    writes("*N*N")
$)

let show(f, n, x, y) be
    writef("sudan(%I4,%I4,%I4) = %I6*N", n, x, y, f(n, x, y))

let start() be
$(  showtable(sudan, 0, 6, 5)
    showtable(sudan, 1, 6, 5)
    wrch('*N')
    show(sudan, 1, 3, 3)
    show(sudan, 2, 1, 1)
    show(sudan, 2, 2, 1)
    show(sudan, 3, 1, 1)
$)