Changed functions in modules.lua and created circles.lua

hare.lua contains now everything from Al Sweigarts book and modules is my interpretation from it with a few tweaks.
Additionally I've created a circles.lua module. This module is used to build circles referenced from https://i.redd.it/swn3e9w8dyc31.jpg

Modules/circles.lua

@@ -0,0 +1,812 @@
+--[[ Modules for generation or building circles in various forms
+--written by TheLux
+--Check https://i.redd.it/swn3e9w8dyc31.jpg to see
+--the references for the numbers]]
+
+-- Check if the modules API is present
+-- and load it. We need it
+if not os.loadAPI('modules.lua') then
+  error('Error! modules.lua is missing. Please insert it into turtle.')
+end
+
+--initial_setup() checks if there is enough
+--material and sets the turtle to the start
+--position and places the first block.
+--Alle circles uses this function
+function initial_circle_setup(material, material_count)
+  -- Check if we have enough material
+  if modules.count_inventory(material) < material_count then
+    print('Error! Not enough blocks of ' .. material)
+    return false
+  end
+
+  turtle.up()
+end
+ 
+
+--place_diagonal() places n blocks in a diagonal manner
+function place_diagonal(amount, material)
+  for i = 1, amount do
+    turtle.turnRight()
+    turtle.forward()
+    modules.select_and_place_down(material)
+    turtle.turnLeft()
+    turtle.forward()
+  end
+end
+
+
+--place_column() places n block in a column
+function place_column(amount, material)
+  turtle.turnRight()
+  for i = 1, amount do
+    turtle.forward()
+    modules.select_and_place_down(material)
+  end
+  turtle.turnLeft()
+  turtle.forward()
+end
+
+
+--place_row() places n block in a row
+function place_column(amount, material)
+  turtle.turnRight()
+  turtle.forward()
+  turtle.turnLeft()
+  for i = 1, amount do
+    modules.select_and_place_down(material)
+    turtle.forward()
+  end
+end
+
+
+
+--place_triangle() places a trinagular block
+function place_column(material)
+  turtle.turnRight()
+  turtle.forward()
+  turtle.turnLeft()
+  modules.select_and_place_down(material)
+  turtle.forward()
+  modules.select_and_place_down(material)
+  turtle.turnRight()
+  turtle.forward()
+  modules.select_and_place_down(material)
+  turtle.turnLeft()
+  turtle.forward()
+end
+
+
+--circle2 build a 2 by 2 circle
+function circle2(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 4)
+
+  modules.select_and_place_down(material)
+  turtle.forward()
+  modules.select_and_place_down(material)
+  turtle.turnRight()
+  turtle.forward()
+  turtle.turnRight()
+  modules.select_and_place_down(material)
+  turtle.forward()
+  turtle.turnRight()
+  modules.select_and_place_down(material)
+  turtle.forward()
+  turtle.turnRight()
+  print('Done building a 2 by 2 circle')
+end
+
+
+--circle3 builds a 3 by 3 wide circle
+function circle3(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 8)
+
+  for i = 1, 4 do
+    for j = 1, 2 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.turnRight()
+  end
+  print('Done building a 3 by 3 circle')
+end
+
+
+--circle4 builds a 4 by 4 wide circle
+function circle4(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 8)
+  turtle.turnLeft()
+  turtle.forward()
+  turtle.turnRight()
+  for i = 1, 3 do
+    for j = 1, 2 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+    turtle.turnRight()
+  end
+  turtle.forward()
+  modules.select_and_place_down(material)
+  turtle.forward()
+  modules.select_and_place_down(material)
+  turtle.turnRight()
+  print('Done building a 4 by 4 circle')
+end
+
+
+--circle5 builds a 5 by 5 wide circle
+function circle5(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 12)
+  turtle.turnLeft()
+  turtle.forward()
+  turtle.turnRight()
+  for i = 1, 3 do
+    for j = 1, 3 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+    turtle.turnRight()
+  end
+  
+  for i = 1, 3 do
+    turtle.forward()
+    modules.select_and_place_down(material)
+  end
+  turtle.turnRight()
+  print('Done building a 5 by 5 circle')
+end
+
+
+--circle6 builds a 6 by 6 wide circle
+function circle6(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 16)
+  turtle.turnLeft()
+  turtle.forward()
+  turtle.turnRight()
+  for i = 1, 3 do
+    for j = 1, 4 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+    turtle.turnRight()
+  end
+  
+  for i = 1, 4 do
+    turtle.forward()
+    modules.select_and_place_down(material)
+  end
+  turtle.turnRight()
+  print('Done building a 4 by 4 circle')
+end
+
+
+--circle7 builds a 7 by 7 wide circle
+function circle7(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 16)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    turtle.turnRight()
+    turtle.forward()
+    modules.select_and_place_down(material)
+    turtle.turnLeft()
+    turtle.forward()
+    turtle.turnRight()
+    for j = 1, 3 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 7 by 7 circle')
+end
+
+
+--circle8 builds a 8 by 8 wide circle
+function circle8(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 20)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    turtle.turnRight()
+    turtle.forward()
+    modules.select_and_place_down(material)
+    turtle.turnLeft()
+    turtle.forward()
+    turtle.turnRight()
+    for j = 1, 4 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 8 by 8 circle')
+end
+
+
+--circle9 builds a 9 by 9 wide circle
+function circle9(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 24)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    turtle.turnRight()
+    turtle.forward()
+    modules.select_and_place_down(material)
+    turtle.turnLeft()
+    turtle.forward()
+    turtle.turnRight()
+    for j = 1, 5 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 9 by 9 circle')
+end
+
+
+--circle10 builds a 10 by 10 wide circle
+function circle10(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 28)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_triangle(material)
+    turtle.turnRight()
+    for j = 1, 4 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 10 by 10 circle')
+end
+
+
+--circle11 builds a 11 by 11 wide circle
+function circle11(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 28)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 5 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 11 by 11 circle')
+end
+
+
+--circle12 builds a 12 by 12 wide circle
+function circle12(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 32)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 4 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 12 by 12 circle')
+end
+
+
+--circle13 builds a 13 by 13 wide circle
+function circle13(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 36)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 5 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 13 by 13 circle')
+end
+
+
+--circle14 builds a 14 by 14 wide circle
+function circle14(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 36)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_diagonal(3, material)
+    turtle.turnRight()
+    for j = 1, 6 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 14 by 14 circle')
+end
+
+
+--circle15 builds a 15 by 15 wide circle
+function circle15(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 36)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_diagonal(1, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 5 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 15 by 15 circle')
+end
+
+
+--circle16 builds a 16 by 16 wide circle
+function circle16(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 44)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_diagonal(1, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 6 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 16 by 16 circle')
+end
+
+
+--circle17 builds a 17 by 17 wide circle
+function circle17(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 48)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_triangle(material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 5 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 17 by 17 circle')
+end
+
+
+--circle18 builds a 18 by 18 wide circle
+function circle18(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 48)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_diagonal(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 6 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 18 by 18 circle')
+end
+
+
+--circle19 builds a 19 by 19 wide circle
+function circle19(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 52)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_diagonal(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 7 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 19 by 19 circle')
+end
+
+
+--circle20 builds a 20 by 20 wide circle
+function circle20(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 56)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_row(2, material)
+    modules.place_column(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 6 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 20 by 20 circle')
+end
+
+
+--circle21 builds a 21 by 21 wide circle
+function circle21(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 56)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_diagonal(3, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 7 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 21 by 21 circle')
+end
+
+
+--circle22 builds a 22 by 22 wide circle
+function circle22(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 60)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(3, material)
+    modules.place_diagonal(3, material)
+    modules.place_column(3, material)
+    turtle.turnRight()
+    for j = 1, 6 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 22 by 22 circle')
+end
+
+
+--circle23 builds a 23 by 23 wide circle
+function circle23(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 64)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_row(2, material)
+    modules.place_diagonal(1, material)
+    modules.place_column(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 7 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 23 by 23 circle')
+end
+
+
+--circle24 builds a 24 by 24 wide circle
+function circle24(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 64)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(3, material)
+    modules.place_diagonal(4, material)
+    modules.place_column(3, material)
+    turtle.turnRight()
+    for j = 1, 6 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 24 by 24 circle')
+end
+
+
+--circle25 builds a 25 by 25 wide circle
+function circle25(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 68)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_row(2, material)
+    modules.place_diagonal(2, material)
+    modules.place_column(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 7 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 25 by 25 circle')
+end
+
+
+--circle26 builds a 26 by 26 wide circle
+function circle26(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 72)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_row(2, material)
+    modules.place_diagonal(2, material)
+    modules.place_column(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 8 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 26 by 26 circle')
+end
+
+
+--circle27 builds a 27 by 27 wide circle
+function circle27(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 76)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(3, material)
+    modules.place_diagonal(1, material)
+    modules.place_row(2, material)
+    modules.place_column(2, material)
+    modules.place_diagonal(1, material)
+    modules.place_column(3, material)
+    turtle.turnRight()
+    for j = 1, 7 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 27 by 27 circle')
+end
+
+
+--circle28 builds a 28 by 28 wide circle
+function circle28(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 76)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(2, material)
+    modules.place_row(2, material)
+    modules.place_diagonal(3, material)
+    modules.place_column(2, material)
+    modules.place_column(2, material)
+    turtle.turnRight()
+    for j = 1, 7 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 28 by 28 circle')
+end
+
+
+--circle29 builds a 29 by 29 wide circle
+function circle29(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 80)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(3, material)
+    modules.place_row(2, material)
+    modules.place_diagonal(3, material)
+    modules.place_column(2, material)
+    modules.place_column(3, material)
+    turtle.turnRight()
+    for j = 1, 7 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 29 by 29 circle')
+end
+
+
+--circle30 builds a 30 by 30 wide circle
+function circle30(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 84)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(3, material)
+    modules.place_diagonal(1, material)
+    modules.place_row(2, material)
+    modules.place_diagonal(1, material)
+    modules.place_column(2, material)
+    modules.place_diagonal(1, material)
+    modules.place_column(3, material)
+    turtle.turnRight()
+    for j = 1, 8 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 30 by 30 circle')
+end
+
+
+--circle31 builds a 31 by 31 wide circle
+function circle31(material)
+  -- Start the initial Setup and place the turtle in
+  -- the right position
+  modules.initial_setup(material, 84)
+  turtle.turnLeft()
+  turtle.forward()
+  for i = 1, 4 do
+    modules.place_row(3, material)
+    modules.place_row(2, material)
+    modules.place_diagonal(4, material)
+    modules.place_column(2, material)
+    modules.place_column(3, material)
+    turtle.turnRight()
+    for j = 1, 7 do
+      turtle.forward()
+      modules.select_and_place_down(material)
+    end
+    turtle.forward()
+  end
+  turtle.back()
+  turtle.turnRight()
+  print('Done building a 31 by 31 circle')
+end
+

Modules/hare.lua

@@ -34,4 +34,95 @@ function selectEmptySlot()
   return false -- couldn't find empty space
 end
 
+-- countInventory() returns the total
+-- numer of items in the inventory
+function countInventory()
+    local total = 0
 
+    for slot = 1, 16 do
+        total = total + turtle.getItem(slot)
+    end
+    return total
+end
+
+-- selectAndPlaceDown() selects a nonempty slot
+-- and places a block from it under the turtle
+function selectAndPlaceDown()
+    for slot = 1, 16 do
+        if turtle.getItemCount(slot) > 0 then
+            turtle.select(slot)
+            turtle.placeDown()
+            return
+        end
+    end
+end
+
+
+-- buildWall() creates a wall stretching
+-- in front of the turtle
+function buildWall(length, height)
+    if modules.countInventory() > length * height then
+        return false --not enough block
+    end
+
+    turtle.up()
+
+    local movingForward = true
+
+    for currentHeight = 1, height do
+        for currentLength = 1, length do
+            selectAndPlaceDown() -- Place the block
+            if movingForward and currentLength ~= length then
+                turtle.forward()
+            elseif not movingForward and currentLength ~= length then
+                turtle.back()
+            end
+        end
+        if currentHeight ~= height then
+            turtle.up()
+        end
+        movingForward = not movingForward
+    end
+
+    -- done building wall; move to end position
+    if movingForward then
+        -- turtle is near the start position
+        for currentLength = 1, length do
+            turtle.forward()
+        end
+    else
+        -- turtle is near the end position
+        turtle.forward()
+    end
+
+    -- move down to the ground
+    for currentHeight = 1, height do
+        turtle.down()
+    end
+
+    return true
+end
+
+-- buildRoom() constructs four walls
+-- and a ceiling
+function buildRoom(length, width, height)
+    if hare.countInventory() < (((length -1) * height * 2) +
+        ((width -1) * height * 2)) then
+        return false -- not enough blocks
+    end
+
+    -- build the four walls
+    buildWall(length -1, height)
+    turtle.turnRight()
+
+    buildWall(width - 1, height)
+    turtle.turnRight()
+
+    buildWall(length - 1, height)
+    turtle.turnRight()
+
+    buildWall(width - 1, height)
+    turtle.turnRight()
+
+    return true
+end

Modules/modules.lua

@@ -4,15 +4,15 @@ Provides useful utility functions.]]
 -- selectItem() selects the inventory
 -- slot with the named item, returns
 -- true if found and false if not
-function selectItem(name)
+function select_item(name)
 -- check all inventory slots
  local item
-  for slot = 1, 16 do
+   for slot = 1, 16 do
-    item = turtle.getItemDetail(slot)
+     item = turtle.getItemDetail(slot)
-    if item ~= nil and item['name'] == name then
+     if item ~= nil and item['name'] == name then
-      turtle.select(slot)
+       turtle.select(slot)
-      return true
+       return true
-    end
+     end
   end
 
   return false  -- couldn't find item
@@ -22,7 +22,7 @@ end
 -- selectEmptySlot() selects inventory
 -- slot that is empty, returns true if
 -- found, false if no empty spaces
-function selectEmptySlot()
+function select_emptySlot()
 
   -- loop through all slots
   for slot = 1, 16 do  
@@ -35,70 +35,96 @@ function selectEmptySlot()
 end
 
 -- countInventory() returns the total
--- numer of items in the inventory
+-- numer of a given minecraft id item in the inventory
-function countInventory()
+function count_inventory(minecraft_id)
-    local total = 0
+  local total = 0
 
-    for slot = 1, 16 do
+  for slot = 1, 16 do
-        total = total + turtle.getItem(slot)
+    if turtle.getItemDetail(slot) == 'minecraft:' .. minecraft_id  then
+      total = total + turtle.getItem(slot)
     end
-    return total
+  end
+  return total
 end
 
--- selectAndPlaceDown() selects a nonempty slot
+-- selectAndPlaceDown() selects a slot with given
--- and places a block from it under the turtle
+-- minecraft id and places a block from it under the turtle
-function selectAndPlaceDown()
+function select_and_place_down(minecraft_id)
-    for slot = 1, 16 do
+  for slot = 1, 16 do
-        if turtle.getItemCount(slot) > 0 then
+    if turtle.getItemDetail(slot) == 'minecraft:' .. minecraft_id  then
-            turtle.select(slot)
+      turtle.select(slot)
-            turtle.placeDown()
+      turtle.placeDown()
-            return
+      return
-        end
     end
+  end
 end
 
 
--- buildWall() creates a wall stretching
+-- build_wall() creates a wall stretching
 -- in front of the turtle
-function buildWall(length, height)
+function build_wall(length, height)
-    if modules.countInventory() > length * height then
+  if modules.count_inventory() > length * height then
-        return false --not enough block
+    return false --not enough block
-    end
+  end
 
-    turtle.up()
+  turtle.up()
 
-    local movingForward = true
+  local movingForward = true
 
-    for currentHeight = 1, height do
+  for currentHeight = 1, height do
-        for currentLength = 1, length do
+    for currentLength = 1, length do
-            selectAndPlaceDown() -- Place the block
+      select_and_place_down() -- Place the block
-            if movingForward and currentLength ~= length then
+      if movingForward and currentLength ~= length then
-                turtle.forward()
-            elseif not movingForward and currentLength ~= length then
-                turtle.back()
-            end
-        end
-        if currentHeight ~= height then
-            turtle.up()
-        end
-        movingForward = not movingForward
-    end
-
-    -- done building wall; move to end position
-    if movingForward then
-        -- turtle is near the start position
-        for currentLength = 1, length do
-            turtle.forward()
-        end
-    else
-        -- turtle is near the end position
         turtle.forward()
+      elseif not movingForward and currentLength ~= length then
+        turtle.back()
+      end
     end
-
+    if currentHeight ~= height then
-    -- move down to the ground
+      turtle.up()
-    for currentHeight = 1, height do
-        turtle.down()
     end
+    movingForward = not movingForward
+  end
 
-    return true
+  -- done building wall; move to end position
+  if movingForward then
+    -- turtle is near the start position
+    for currentLength = 1, length do
+      turtle.forward()
+    end
+  else
+    -- turtle is near the end position
+    turtle.forward()
+  end
+
+  -- move down to the ground
+  for currentHeight = 1, height do
+    turtle.down()
+  end
+
+  return true
+end
+
+-- build_room() constructs four walls
+-- and a ceiling
+function build_room(length, width, height)
+  if modules.count_inventory() < (((length -1) * height * 2) +
+    ((width -1) * height * 2)) then
+    return false -- not enough blocks
+  end
+
+  -- build the four walls
+  build_wall(length -1, height)
+  turtle.turnRight()
+
+  build_wall(width - 1, height)
+  turtle.turnRight()
+
+  build_wall(length - 1, height)
+  turtle.turnRight()
+
+  build_wall(width - 1, height)
+  turtle.turnRight()
+
+  return true
 end