"Produces the [[stream|Iterable]] that results from repeated application of the given [[function|next]] to the given [[first]] element of the stream, until the function first returns [[finished]]. If the given function never returns `finished`, the resulting stream is infinite. For example: loop(0)(2.plus).takeWhile(10.largerThan) produces the stream `{ 0, 2, 4, 6, 8 }`." tagged("Streams") shared {Element+} loop<Element>( "The first element of the resulting stream." Element first)( "The function that produces the next element of the stream, given the current element. The function may return [[finished]] to indicate the end of the stream." Element|Finished next(Element element)) => let (start = first) object satisfies {Element+} { first => start; empty => false; function nextElement(Element element) => next(element); iterator() => object satisfies Iterator<Element> { variable Element|Finished current = start; shared actual Element|Finished next() { if (!is Finished result = current) { current = nextElement(result); return result; } else { return finished; } } }; };