Runtime: Enumerable.Repeat should allow for infinite repetition

[ahoka]

Enumerable.Repeat should have an overload with the following signature:

public static System.Collections.Generic.IEnumerable Repeat (TResult element);

The behavior would be repeating the value infinitely to allow composing lazy sequences without having to provide int.MaxValue or similar workarounds (which have the obvious limitation of having a bound).

~cs
static class Example
{
public static IEnumerable ToBinary(uint i) => Enumerable.Repeat(i)
.Select((num, shift) => num >> shift)
.TakeWhile(x => x != 0)
.Select(x => (x & 1) == 1);
}
~

[gfoidl]

As rather uncommon usecase I think this shouldn't get into corefx.

But you can write such a method quite simple:
c# public static IEnumerable<T> RepeatEndless<T>(T element) { while (true) { yield return element; } }

BTW: see API Review Process

[ahoka]

I think the less common use case is actually the Repeat(x, y), because it's a special case of Repeat(x) as the former could be implemented with idiomatic LINQ:

~cs
var _ = Enumerable.Repeat(x).Take(y);
~

Of course it is trivial to implement it with a generator, but that breaks the flow of a functional style C# program.