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functional-programmingdlambda-calculusy-combinator

Y-combinator in D?

I'm trying to learn the Y-combinator better (I sort of understand it in Scheme) and implement it in D 2.0, and I'm failing pretty miserably:

auto fact = delegate(uint delegate(uint) recurse)
{
    return delegate(uint n)
    {
        return n > 1 ? n * recurse(n - 1) : 1;
    };
};

fact(fact)(5);

This doesn't work, for the obvious reason that I can't pass fact to fact (what would its type be?). And besides, I still need fact's name to pass to itself, so it wouldn't work anyway, right?

But... how do I go about implementing the Y-combinator in D?

Solution

  • See an extensive explanation here.