View difference between Paste ID: m2QNx7Le and Rrjp2E40

 --   Block actions combinators v1 (go)
 --
 -- f b u d l r   -- Move forward, backward, up, down, turn left, turn right
 -- F B U D         -- same moves, but move until block detected
 -- m M   --  mine block, mine blocks while block present (usefull for gravel mining)
 -- [commands lastcommand]   --  loop while lastcommand returns success
 -- commandNUMBER   -- loop command NUMBER times
 -- [commands]NUMBER -- loop commands list NUMBER times
 -- >DIGIT   --   place block from DIGIT slot. When DIGIT == 0, place first available
 -- ^DIGIT   --   place block up
 -- _DIGIT   --   place block down
 
 local tArgs = { ... }
 if #tArgs ~= 1 then
   print("Usage: go <list of commands>")
   return
 end
 
 -- Enables mob detection capabilities of CAPS move forward for noncaps forward
 local function mdForward()
   if turtle.detect() == false then
     turtle.forward()
     return true
   else
     return false
   end
 end
 
 -- CAPS-letter commands evaluator, move-only
 -- Remove code duplication by encapsulating common pattern in function
 local function mdMove(command, detector)
   while detector() == false do
         command()
   end
 end
 
 -- CAPS-letter commands evaluator, dig-only
 -- Remove code duplication by encapsulating common pattern in function
 local function mdDig(command, detector)
   while detector() do
         command()
         sleep(0.4)
   end
 end
 
 -- Evaluate prefix commands
 local function runPrefixCmd(ch, digCmd, detectCmd, placeCmd)
   local chCode = string.byte(ch, 1) - 48
   if false then
   elseif ch == 'm' then return true, digCmd()
   elseif ch == 'M' then mdDig(digCmd, detectCmd); return true, false -- todo: better result return
   elseif ch == '0' then return true, placeCmd()
   elseif chCode > 0 and chCode < 10 then
         turtle.select(chCode)
         res = placeCmd()
         return true, res
   end
   return false, false
 end
 
 -- Lua specific array length
 local function lngth(lst)
   if lst == nil then return 0 else return #lst end
 end
 
 local function parseNumber(st)
   _, _, num, rest = string.find(st, "^(%d+)(.*)$")
   return num, lngth(st) - lngth(rest)
 end
 
 local function parseLoop(st)
   _, _, loop, rest = string.find(st, "^(%b[])(.*)$")
   if loop ~= nil and loop ~= '' then
         return loop:sub(2,-2), lngth(st) - lngth(rest)
   elseif st:sub(1,1) == '[' then return nil, 1
   else return nil, 0
   end
 end
 
 function go(command)
   local i = 1
   local prevCommand = ''
   local result = false
 
   while i <= #command do
         local ch = command:sub(i, i)
         local nextCh = i == #command and '' or command:sub(i+1, i+1)
 
         local number, nLen = parseNumber(command:sub(i))
         local loop, lLen   = parseLoop(command:sub(i))
 
         -- if we found number, repeat last command number times
         if number ~= nil then
           number = tonumber(number)
           while number > 1 do
                 go(prevCommand)
                 number = number - 1
           end
           i = i + nLen - 1
         -- if we found loop, parse possible number and evaluate expression
         elseif loop ~= nil then
           local number, nLen = parseNumber(command:sub(i + lLen))
           if number ~= nil then
                 number = tonumber(number)
                 while number > 0 do
                   go(loop)
                   number = number - 1
                 end
                 i = i + nLen
           else
                 while go(loop) do end
           end
           i = i + lLen - 1
 
         elseif ch == 'f' then result = mdForward()
         elseif ch == 'b' then result = turtle.back()
         elseif ch == 'u' then result = turtle.up()
         elseif ch == 'd' then result = turtle.down()
 
         elseif ch == 'F' then mdMove(mdForward, turtle.detect)
         elseif ch == 'B' then go("aFa") -- this is not primitive
         elseif ch == 'U' then mdMove(turtle.up, turtle.detectUp)
         elseif ch == 'D' then mdMove(turtle.down, turtle.detectDown)
 
         elseif ch == 'l' then turtle.turnLeft()
         elseif ch == 'r' then turtle.turnRight()
         elseif ch == 'a' then go("ll")
 
         elseif ch == 'm' then result = turtle.dig()
         elseif ch == 'M' then mdDig(turtle.dig, turtle.detect)
 
         elseif ch == '>' then
           local result1,result2 = runPrefixCmd(nextCh, turtle.dig, turtle.detect, turtle.place)
           if result1 then
                 i = i + 1 -- todo: better prefix parsing
           end
           result = result2
         elseif ch == '^' then
           local result1,result2 = runPrefixCmd(nextCh, turtle.digUp, turtle.detectUp, turtle.placeUp)
           if result1 then
                 i = i + 1
           end
           result = result2
         elseif ch == '_' then
           local result1,result2 = runPrefixCmd(nextCh, turtle.digDown, turtle.detectDown, turtle.placeDown)
           if result1 then
                 i = i + 1
           end
           result = result2
         end
 
         prevCommand = ch
         i = i + 1
   end
   return result
 end
 
 go(tArgs[1])