public static U FoldR <U>(Func <T, U, U> f, Cons <T> t, U start = default(U))
{
return((t == null) ? start : f(t.head, FoldR(f, t.tail)));
}
// In Python, these are not only free functions, but also work on
// anything that duck-types as a Cons, like LazyCons. In C#, I'd
// have to create an ICons<T> interface for that. I suppose that's
// what I'm supposed to do--and an ICons for Generic.ICons<T> to
// inherit, just like the stuff in .NET. Because what everyone wants
// is more boilerplate than Java. Anyway, as static members of Cons
// that work on Cons, these work just fine.
public static U FoldL <U>(Func <U, T, U> f, Cons <T> t, U start = default(U))
{
return((t == null) ? start : FoldL(f, t.tail, f(start, t.head)));
}
public void push(T value)
{
lst = new Cons <T>(value, lst);
}
static void Main(string[] args)
{
var xs = Cons <int> .FromEnumerable(new int[] { 1, 2, 3 });
foreach (var x in xs)
{
Console.WriteLine(x);
}
var ys = xs.tail;
xs.tail.head *= -1;
foreach (var y in ys)
{
Console.WriteLine(y);
}
var zs = LazyCons <int> .FromEnumerable(xs);
foreach (var z in zs)
{
Console.WriteLine(z);
}
foreach (var z in zs)
{
Console.WriteLine(z);
}
Func <int, Cons <int>, Cons <int> > cons = (q, qs) => new Cons <int>(q, qs);
var ws = Cons <int> .FoldR(cons, xs);
foreach (var w in ws)
{
Console.WriteLine(w);
}
var vs = Cons <int> .FoldL(Funky.Flip(cons), xs);
foreach (var v in vs)
{
Console.WriteLine(v);
}
var ss = new Stack <int>();
ss.push(1);
ss.push(2);
Console.WriteLine(ss.pop());
Console.WriteLine(ss.pop());
Console.WriteLine(ss.pop(0));
try
{
Console.WriteLine(ss.pop());
}
catch (Exception e)
{
Console.WriteLine(e);
}
var ms = new MStack <int>();
ms.push(1);
ms.push(2);
Console.WriteLine(ms.pop());
Console.WriteLine(ms.pop());
Console.WriteLine(ms.pop(0));
try
{
Console.WriteLine(ms.pop());
}
catch (Exception e)
{
Console.WriteLine(e);
}
}
public Cons(T head = default(T), Cons <T> tail = null)
{
this.head = head;
this.tail = tail;
}