Recursive lambda functions?

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On Monday, 30 December 2013 at 21:15:43 UTC, Ilya Yaroshenko 
wrote:
> On Monday, 30 December 2013 at 12:24:28 UTC, lomereiter wrote:
>> Use Y combinator?
>> http://forum.dlang.org/thread/mailman.157.1385247528.2552.digitalmars-d-learn@puremagic.com#post-l6rgfq:24g5o:241:40digitalmars.com
>
> This is not lambda =(
>
> I want something like
>
> enum factrorial5 = (a => a == 0 ? 1 : a * __lambda(a-1))(5);
> //Recursive pure lambda function

You can do this with __traits(parent, {}), but it's ugly.

	auto fact = function(int n)
	{
		if (n == 0)
		{
			return 1;
		}
		else
		{
			enum self = __traits(parent, {});
			
			return n * self(n - 1);
		}
	};

Unfortunately, a shorter version written with the lambda syntax 
doesn't work, it just segfaults:

auto fact = (int n) =>
                 (n < 2)
                     ? 1
                     : n * __traits(parent, {})(n - 1);