starlit  Diff

		for cat, vals in pairs(b) do
			if not new[cat] then
				new[cat] = lib.tbl.copy(vals)
			else
				local f = fields[cat].op
				for k,v in pairs(vals) do
					local n = f(new[cat][k], v, 1)

					new[cat][k] = n > 0 and n or nil
				end
			end
		end
		return new
	end;

	__mul = function(x,n)

		local new = fab {}

		for cat, vals in pairs(x) do
			new[cat] = {}
			local f = fields[cat].op
			for k,v in pairs(vals) do
				local num = f(v,nil,n)

				new[cat][k] = num > 0 and num or nil
			end
		end
		return new
	end;

	__div = function(x,n)
		return x * (1/n)
	end;
}

starlit.type.fab = fab

		for cat, vals in pairs(b) do
			if not new[cat] then
				new[cat] = lib.tbl.copy(vals)
			else
				local f = fields[cat].op
				for k,v in pairs(vals) do
					local n = f(new[cat][k], v, 1)
					if type(n) == 'number' and n < 0 then n = nil end
					new[cat][k] = n
				end
			end
		end
		return new
	end;

	__mul = function(x,n)
		if n == 1 then return fab.clone(x) end
		local new = fab {}
		if n == 0 then return new end
		for cat, vals in pairs(x) do
			new[cat] = {}
			local f = fields[cat].op
			for k,v in pairs(vals) do
				local num = f(v,nil,n)
				if type(num) == 'number' and n < 0 then n = nil end
				new[cat][k] = num
			end
		end
		return new
	end;

	__div = function(x,n)
		return x * (1/n)
	end;
}

starlit.type.fab = fab