farm.lua

local config = {
    harvest = {
        name = "minecraft:cactus",
       instructions = {
            turltle.digDown,turtle.down,turtle.digDown,turtle.up,turtle.up,turtle.forward
            }
        }

    rightTurn = {
        name = "minecraft:stonebrick",
        instructions = {
            turtle.
        }
    }
}

local function exec(tbl)
    for _,v in pairs(tbl.instructions) do
        v()
    end
end

while true do
local bool, block = turtle.inspectDown()

    if bool == true then
        if block == config.harvest.name then
            exec(config.harvest)
        elseif block == config.left.name then
            exec(config.left)
        elseif block == config.right.name then
            exec(config.right)
        elseif block == config.chest then
            exec(config.chest)
        elseif bool == false then
            turtle.forward()
        end
    end
end