Engine IntList newgs not used

[akbooer]

iProlog/IP/src/iProlog/Engine.java

Lines 870 to 876 in 62b20e6

	final int[] gs = pushBody(b, head, C0);
	final IntList newgs = IntList.tail(IntList.app(gs, IntList.tail(G.gs)));
	G.k = k + 1;
	if (!IntList.isEmpty(newgs))
	return new Spine(gs, base, IntList.tail(G.gs), ttop, 0, cls);
	else
	return answer(ttop);

This looks like a very expensive way of computing

(gs.length > 1) || (G.gs.length > 1)

as IntList newgs is otherwise unused?

Just seeking to understand why this is written this way, as I am in the process of converting the engine into the Lua language (what else to do in lockdown?) Preliminary speed tests are very encouraging. This whole implementation (plus the "Hitchhiker" paper, and the YouTube tutorial) is otherwise wonderfully clear and straight-forward.

Thanks for your work, I had been looking for a compact Prolog implementation for quite a while!

Tony