View difference between Paste ID: 5KnL2JSN and 99MtfLBp

 acceptableItems = {'minecraft:diamond','minecraft:coal','minecraft:iron_ore','minecraft:emerald','minecraft:gold_ore','draconicevolution:draconium_dust'}
 acceptableItemsLength = 6
 -- 1 breaks up, -1 breaks down
 function destroy (direction)
 	if direction == 1 then
 		turtle.digUp()
 		turtle.up()
 	elseif direction == -1 then
 		turtle.digDown()
 		turtle.down()
 	else
 		error('invalid direction')
 	end
     turtle.dig()
     turtle.turnLeft()
     turtle.turnLeft()
     turtle.dig()
     turtle.turnLeft()
     turtle.turnLeft()
 end
 
 -- if coal slot (1) has more than one coal, use
 function refuel ()
 	if turtle.getItemCount(1) > 1 then
 		temp = turtle.getSelectedSlot()
 		turtle.select(1)
 		turtle.refuel(turtle.getItemCount()-1)
 		turtle.select(temp)
 	end
 end
 
 -- remove all items not in list
 function purge ()
 	for i=2,16 do
 		keep = false
 		for j=1,acceptableItemsLength do
-				break
+
 				keep = true
-			if j == acceptableItemsLength then
+
-				turtle.select(i)
+
-				turtle.drop()
+		if not keep then
 			turtle.select(i)
 			turtle.drop(i)
 		end
 	end
 end
 
 -- returns true if every slot is completely full
 function turtleInvFull ()
 	fullCount = 0; -- # of slots full
 	for i=2,16 do
 		if turtle.getItemSpace(i) == 0 then
 			fullCount = fullCount + 1;
 		end
 	end
 	return fullCount == 15;
 end
 
 
 while (turtle.getFuelLevel() > 0) and not turtleInvFull() do
 	-- mining down
 	repeat
 		success, data = turtle.inspectDown()
 		destroy(-1)
 		refuel()
 		purge()
 	until data.name == 'minecraft:bedrock'
 
 	-- moves to new spot to mine up
 	for i=1,3 do
 		turtle.dig()
 		turtle.forward()
 	end
 
 	-- end if turtle inv completely full
 	if turtleInvFull() then
 		break
 	end
 
 	-- mining up
 	for i=2,70 do
 		destroy(1)
 		refuel()
 		purge()
 	end
 
 	-- moves to new spot to mine down
 	for i=1,3 do
 		turtle.forward()
 		turtle.dig()
 	end
 end