public void UseMeertensTree()
{
IRoseTree <Unit, int> meertensTree =
RoseTree.Node(Unit.Instance,
RoseTree.Node(Unit.Instance,
RoseTree.Node(Unit.Instance,
new RoseLeaf <Unit, int>(2112)),
new RoseLeaf <Unit, int>(42),
new RoseLeaf <Unit, int>(1337),
new RoseLeaf <Unit, int>(90125)),
RoseTree.Node(Unit.Instance,
new RoseLeaf <Unit, int>(1984)),
new RoseLeaf <Unit, int>(666));
Assert.False(meertensTree.IsLeaf().ToBool());
}
public static IChurchBoolean IsNode <N, L>(this IRoseTree <N, L> source) => new ChurchNot(source.IsLeaf());