AFAIU the problem, from a theoretical point of view, is not that you need to pass the self function, but how to define it. In pure lambda calculus, there are no

AFAIU the problem, from a theoretical point of view, is not that you need to pass the self function, but how to define it. In pure lambda calculus, there are no named functions, just lambdas, so you actually need the Y combinator for recursion.