Visit http://turtlebits.net/ to run your programs.

Turtle Bits
uses the language CoffeeScript designed by Jeremy Ashkenas in 2009,
with await/defer extensions created by Maxwell Krohn in 2012,
and the jQuery-turtle plugin devleoped by the author in 2011,
built on the jQuery library invented by John Resig in 2006.
Turtlebits runs on modern HTML5 browsers.
This work is inspired by the beloved LOGO language
created by Seymour Papert and Wally Feurzeig in 1967.

Special thanks to the middle school students in Lincoln Massachusetts
and at Dorchester McCormack who vetted this material.

Bugs and ideas to https://github.com/davidbau/jquery-turtle/issues

This book is typeset in Łukasz Dziedzic's 2010 open font Lato
and Paul D. Hunt's 2012 Adobe Source Code Pro.

1. Lines

First

pen red
fd 50
rt 90

Square

pen blue
fd 50; rt 90
fd 50; rt 90
fd 50; rt 90
fd 50; rt 90

Triangle

pen black
fd 70; rt 120
fd 70; rt 120
fd 70; rt 120

House

speed 5
pen green
fd 30; lt 90
fd 10; rt 120
fd 80; rt 120
fd 80; rt 120
fd 10; lt 90
fd 30; rt 90
fd 60; rt 90

Star

x = 144
pen gold
fd 100; rt x
fd 100; rt x
fd 100; rt x
fd 100; rt x
fd 100; rt x

2. Points

Dot Row

rt 90; dot lightgray
fd 30; dot gray
fd 30; dot()
fd 30

Lighthouse

pen crimson
fd 60; label 'UP'
rt 30
fd 40; rt 120; dot gold, 30
fd 40; rt 30; label 'DOWN'
fd 60; rt 90
fd 40; rt 90

Smiley

speed 10
dot yellow, 160
fd 20
rt 90
fd 25
dot black, 20
bk 50
dot black, 20
bk 5
rt 90
fd 40
pen black, 7
lt 30
fd 20
lt 60
fd 40
lt 60
fd 20
ht()

Bullseye

x = 18
see x * 5
dot black, x * 5
dot white, x * 4
dot black, x * 3
dot white, x * 2

3. Loops

Rectangle

pen green
for d in [50, 100, 50, 100]
  fd d
  rt 90

Rainbow

for c in [red
          orange
          yellow
          green
          blue
          violet]
  pen c
  fd 100
  bk 100
  slide 10, 5

Range

see [1..5]
see [1...5]

Square Loop

pen blue
for x in [1..4]
  fd 50
  rt 90

360 Loop

speed 100
pen red
for x in [1..360]
  fd 1
  rt 1

Descending Loop

pen purple
for x in [30..1] by -1
  fd x
  rt 30

4. Nesting

Violet

pen blueviolet
for x in [1..5]
  rt 72
  for y in [1..3]
    fd 50
    rt 120

Combinations

for outside in [skyblue, violet, pink]
  for inside in [palegreen, orange, red]
    dot outside, 21
    dot inside, 7
    fd 25
    rt 36

Decorated Nest

pen turquoise
for y in [1..10]
  dot blue
  for x in [1..4]
    fd 50
    rt 90
  lt 36
  bk 50

Catalog

speed 100
rt 90
for color in [red, gold, green, blue]
  slide 40, -160
  for sides in [3..6]
    pen 'path'
    for x in [1..sides]
      fd 100 / sides
      lt 360 / sides
    fill color
    fd 40

5. Functions

Square Function

square = (x) ->
  for y in [1..4]
    fd x
    rt 90
pen red
square 80

Polygon Function

polygon = (c, s, n) ->
  pen c
  for x in [1..n]
    fd s
    rt 360 / n
polygon blue, 70, 5
polygon orange, 25, 6

Rule Function

rule = (list) ->
  for x in list
    fd x; bk x
    slide 10, 0
pen black
rule [50, 10, 20, 10, 50, 10, 20, 10, 50]

Rotate Function

rotate = (x, shape) ->
  for z in [1..x]
    shape()
    rt 360 / x

pen deeppink
rotate 3, -> fd 50

pen null; bk 70
rotate 4, ->
  dot springgreen, 30
  fd 30

bk 80; pen 'path'
rotate 5, ->
  rotate 3, -> fd 50
fill 'violet strokeStyle blue'

6. Time

Pause

speed 100
pen red
for x in [1..20]
  fd 80
  rt 100
  if x is 10
    delay 2000

Second Hand

speed Infinity
advance = ->
  pen lightgray
  bk 100
  rt 5
  pen red
  fd 100
tick advance

Countdown

seconds = 5
tick ->
  if seconds is 0
    write "Time's up!"
    tick off
  else
    write seconds
    seconds = seconds - 1

Click Draw

speed Infinity
pen green

tick ->
  moveto lastclick

Move Draw

speed Infinity
pen orange

tick 100, ->
  turnto lastmousemove
  fd 1

7. Output

Poetry and Song

cry = (who, query) ->
  write "Oh #{who}, #{who}!"
  write "#{query} #{who}?"
cry "Romeo", "Wherefore art thou"
cry "kitty", "What did you eat"
play "fc/c/dcz"

Imagery

url = "http://upload.wikimedia.org/wikipedia" +
      "/commons/6/61/Baby_Gopher_Tortoise.jpg"
write """<center><img src="#{url}" width=100>
      </center>"""

Bold Statement

n = write "<h1>Notice</h1>"
write """
<p>This long paragraph has
<b>bold</b>, <i>italic</i>,
and <u>underlined</u> text.
Horizontal rule below.</p>
"""
write "<hr>"
write """
<p><a href="//turtlebits.net/">
Link</a> with an &lt;a&gt;.
</p>
"""
n.css { background: pink }

Graffiti

n = write "<h1>Notice</h1>"
write """
<p>This long paragraph has
<b>bold</b>, <i>italic</i>,
and <u>underlined</u> text.
</p>"""
n.css {
  background: pink
  display: 'inline-block'
}
n.pen purple, 10
n.bk 80
n.rt 45
n.fd 50

8. Input

Button Control

pen sienna
button 'R', -> rt 10
button 'F', -> fd 10
button 'L', -> lt 10
button 'D', -> dot 'darkslateblue'

Polygon to Order

write "How many sides?"
read (sides) ->
  write "Color?"
  read (color) ->
    pen color
    for x in [1..sides]
      fd 30
      rt 360 / sides

Guess My Number

secret = random [1..100]
turns = 5
write "Guess my number."
write "You get #{turns} guesses."

dopick = (pick) ->
  if pick is secret
    write "You got it!"
    return
  if 1 <= pick < secret
    write "Too small! "
    turns = turns - 1
  else if secret < pick <= 100
    write "Too big! "
    turns = turns - 1
  else
    write "It's a number 1 to 100."
  if turns > 1
    write "#{turns} left."
    readnum dopick
  else if turns is 1
    write "Last guess!"
    readnum dopick
  else
    write "Game over."
    write "It was #{secret}."

readnum dopick

9. Numbers

Parsing

write '5' + '3'
write Number('5') + Number('3')

Ways to Count

counter = 0
write ++counter + 'a'
write (counter += 1) + 'b'
write (counter = counter + 1) + 'c'

Circle Measurements

area = (radius) ->
  Math.PI * radius * radius

circumference = (radius) ->
  2 * Math.PI * radius

for r in [1, 5, 10]
  write 'radius ' + r
  write 'a ' + area r
  write 'c ' + circumference r

Hypotenuse

hypotenuse = (a, b) ->
  Math.sqrt(a * a + b * b)

write hypotenuse 3, 4
write hypotenuse 5, 12
write hypotenuse 10, 10
write Math.floor(hypotenuse(10, 10))

Euclid's Method

gcf = (a, b) ->
  if a > b
    return gcf b, a
  remainder = b % a
  if remainder is 0
    return a
  gcf remainder, a

for x in [80..88]
  write "gcf(120,#{x})=" +
      gcf(120, x)

10. Computation

Power

power = (x, p) ->
  answer = 1
  answer *= x for i in [0...p]
  return answer
for n in [1..5]
  write power(2, n)

Built-in Power

write Math.pow(2, 5)
write Math.pow(2, 0.5)

Factorial

factorial = (x) ->
  if x < 1 then 1
  else x * factorial(x - 1)
for x in [1..4]
  write factorial x

Fibonacci

fib = (n) ->
  if n <= 2
    1
  else
    fib(n - 1) + fib(n - 2)
for x in [3..8]
  write fib x

Complex

mandelbrot = (n, c, z) ->
  if n is 0 or z.r*z.r + z.i*z.i > 4
    return n
  else return mandelbrot n - 1, c, {
    r: c.r + z.r*z.r - z.i*z.i
    i: c.i + 2*z.r*z.i }
speed 100
ht()
scale 150
s = 0.05
for x in [-2..1] by s
  for y in [-1.5..1.5] by s
    n = mandelbrot 20, {r:x,i:y}, {r:x,i:y}
    moveto x, y
    dot "hsl(100,100%,#{5*n}%)", s

11. Objects

Page Coordinates

moveto {pageX: 80, pageY: 50}; pen coral
moveto {pageX: 80, pageY: 10}
moveto {pageX: 30, pageY: 50}
moveto {pageX: 160, pageY: 50}

Plan

plan = [
  {c: dimgray, x: 75,  y: 12}
  {c: gray,    x: 0,   y: 78}
  {c: dimgray, x: -75, y: 5}
  {c: gray,    x: -35, y: -18}
  {c: plum,    x: 0,   y: -62}
  {c: gray,    x: 35,  y: -15}
  {c: black,   x: 0,   y: 95}
]
for record in plan
  pen record.c
  slide record.x, record.y

Scoring

values = {
  a: 1, e: 1, i: 1, l: 1, n: 1, o: 1, r: 1, s: 1, t: 1, u: 1
  d: 2, g: 2, b: 3, c: 3, m: 3, p: 3
  f: 4, h: 4, v: 4, w: 4, y: 4
  k: 5, j: 8, x: 8, q: 10, z: 10
}
score = (word) ->
  total = 0
  for letter in word
    total += values[letter]
  write "#{word}: #{total}"
score x for x in ['bison', 'armadillo', 'giraffe', 'zebra']

Methods

memo = {
  sum: 0
  count: 0
  add: (x) -> @sum += x; @count += 1
  stats: ->
    write 'Total ' + @sum + '/' + @count
    write 'Average ' + @sum / @count
}
memo.add(n) for n in [40..50]
memo.stats()

12. Lists

Primes

primes = []
candidate = 2
while primes.length < 10
  composite = false
  for p in primes
    if candidate % p is 0
      composite = true
      break
  if not composite
    primes.push candidate
    write candidate
  candidate = candidate + 1

Push and Pop

stack = []
pen green
speed Infinity
button 'R', -> rt 30
button 'F', -> fd 10
button 'Push', ->
  dot crimson
  stack.push [getxy(), bearing()]
button 'Pop', ->
  if not stack.length then home(); return
  [xy, b] = stack.pop()
  pen off
  moveto xy
  turnto b
  pen on
  dot pink

Shuffle

suits = ['\u2663', '\u2666', '\u2665', '\u2660']
deck = []
for v in [2..10].concat ['J', 'Q', 'K', 'A']
  deck.push (v + s for s in suits)...
shuffle = (d) ->
  for i in [1...d.length]
    choice = random(i + 1)
    [d[i], d[choice]] = [d[choice], d[i]]
deal = (d, n) -> d.splice(-n)

shuffle deck
for x in [1..3]
  write deal(deck, 5).join('/')

13. Recursion

Recursive Spiral

spiral = (x) ->
  if x > 0
    fd x * 10
    rt 90
    spiral x - 1
pen red
spiral 10

Fractal Fern

speed 1000
fern = (x) ->
  if x > 1
    fd x
    rt 95
    pen red
    fern x * .4
    lt 190
    pen gold
    fern x * .4
    rt 100
    pen green
    fern x * .8
    lt 5
    pen null
    bk x
pen brown
fern 50

Koch Snowflake

speed Infinity
flake = (x) ->
  if x < 3 then fd x
  else
    flake x / 3
    lt 60
    flake x / 3
    rt 120
    flake x / 3
    lt 60
    flake x / 3
pen 'path'
for s in [1..3]
  flake 150
  rt 120
fill 'azure strokeStyle navy'

14. Sets

Red And Blue

r = hatch red
r.pen red
r.rt 45
r.fd 60
b = hatch blue
b.pen blue
b.lt 83
b.fd 40

Scatter

turtle.remove()
crowd = hatch 20
crowd.pen goldenrod
crowd.direct ->
  @rt random 360
  @fd 20 + random 30

Bar Graph

turtle.remove()
forest = hatch 17, olive
forest.direct (j) ->
  x = j - 8
  @rt 90
  @fd x * 10
  @lt 90
  @pen sandybrown
  @fd 100 - x * x

Grid

turtle.remove()
group = hatch 9
group.direct (j) ->
  @fd 50 * Math.floor(j / 3)
  @rt 90
  @fd 50 * (j % 3)
  @dot 2 * (1 + j)
group.delay 1000
group.direct (j) ->
  @pen "hsl(#{j*36},100%,40%)"
  p = j + 3
  for k in [1..p]
    @fd 100 / p
    @lt 360 / p

15. Text

text = """If you can look into the seeds of time
          And say which grain will grow and which will not,
          Speak, then, to me."""

Substr

see text.indexOf 'which'
see text.substr 47, 7

Unicode

see 'charCode', text.charCodeAt(0)
see 'string', String.fromCharCode(73)
for x in [88, 188, 9988]
  see x, String.fromCharCode(x)

Match

see text.match /w....g.../
see text.match /[a-z][a-z]/
see text.match /\s[a-z][a-z]\s/
see text.match /\b[a-z][a-z]\b/
see text.match /\b[a-z][a-z]\b/gi
see text.match /\b[gn][a-z]*\b/g
see text.match /z/

Split

lines = text.split /\n/
see lines[2]
words = text.split /\s+/
see words[0..2]

Groups

pattern = /\b([a-z]+) of ([a-z]+)\b/
matched = pattern.exec text
for g in [0..2]
  see "group #{g}: #{matched[g]}"

Replace

r = text.replace /[A-Z][a-z]*/g,
    "<mark>$&</mark>"
r = r.replace /\n/g,
    "<br>"
r = r.replace /\bw[a-z]*\b/g,
    (x) -> x.toUpperCase()
write r

16. Motion

Gravity

speed Infinity
pen purple
vy = 10
tick 20, ->
  slide 1, vy
  if enclosedby(window)
    vy -= 1
  else
    vy = Math.abs(vy) * 0.9

Not Really Gravity

compare = (a, b) -> if a > b then 1 else if a < b then -1 else 0
speed Infinity
pen red
v = {x: 0, y: 0}
tick 10, ->
  if not lastmousemove then return
  c = pagexy(); a = lastmousemove
  v.x += compare a.pageX, c.pageX
  v.y -= compare a.pageY, c.pageY
  slide v.x, v.y

Chase

defaultspeed Infinity
write "Catch blue before red gets you."
bk 100
r = hatch red
b = hatch blue
tick 10, ->
  turnto lastmousemove
  fd 6
  r.turnto turtle
  r.fd 4
  b.turnto bearing b
  b.fd 3
  if b.touches(turtle)
    write "You win!"
    tick off
  else if r.touches(turtle)
    write "Red got you!"
    tick off
  else if not b.touches(document)
    write "Blue got away!"
    tick off

17. Randomness

Two Dice

onedice = ->
  random [1..6]
twodice = ->
  onedice() + onedice()
for n in [1..5]
  write twodice()

Random Walk

for n in [1..20]
  fd 10
  rt random(181) - 90
  dot gray, 5

Cubism

for n in [1..14]
  pen random [red,black,blue]
  fd random 70
  rt 90

Confetti

for n in [1..300]
  moveto random 'position'
  dot random 'color'

Decimal Random

for n in [1..2]
  write Math.random()

Five Flips

c = [0, 0, 0, 0, 0, 0]
for n in [1..500]
  heads = 0
  for flips in [1..5]
    heads += random 2
  c[heads] += 1
for h of c
  b = write h + ":" + c[h]
  b.css {
    background: skyblue
    width: c[h] }

18. Styles

Thick Lines

pen blue, 10
fd 100; rt 90
pen pink, 3
fd 50; rt 90
pen 'orange ' +
    'lineWidth 10 ' +
    'lineCap square'
fd 100; rt 90
pen black
fd 50

Border

text = write 'Outlined.'
text.css { border: '2px solid red' }
turtle.css { border: '3px dotted blue' }

Font

h = write 'Fancy!'
h.css {
  font: '55px Helvetica'
  fontStyle: 'italic'
}

Text Decoration

write 'Before'
d = write 'Decorated'
write 'After'
d.css {
  display: 'inline-block'
  cursor: 'pointer'
  padding: '10px'
  margin: '-5px'
  opacity: '0.7'
  color: 'white'
  fontSize: '110%'
  letterSpacing: '5px'
  textDecoration: 'underline'
  boxShadow: '1px 1px black'
  background: 'mediumaquamarine'
  transform: 'rotate(10deg)translateX(20px)'
}

19. Selectors

Classes

write """
<style>
.a { text-decoration: underline; }
.b { font-style: italic; }
</style>
"""
write "<p class='a'>Class a</p>"
write "<h3 class='b'>Class b</h3>"
write "<p class='b'>Classes apply to any tag.</p>"

Composites

write """
<style>
i { border: 1px solid black; margin: 2px }
i:nth-of-type(1) { background: gold }
i:nth-of-type(2n+4) { background: skyblue }
i:nth-of-type(3n+9) { background: thistle }
</style>
"""
for x in [1..24]
  write "<i>#{x}</i>"
  write "<wbr>"

jQuery

write "<p><mark>a</mark>v<mark>o</mark>" +
      "c<mark>a</mark>d<mark>o</mark></p>"
$('p').css { fontSize: '200%' }
$('mark').css { background: palegreen }
$('mark').animate {
    padding: '5px' }
$('mark:nth-of-type(2n)').animate {
    opacity: 0.3 }

20. Events

Shift Click

$(document).click (event) ->
  see event
  if event.shiftKey
    pen blue
  else
    pen null
  moveto event

Arrow Keys

pen plum
[L, R, U, D] = [37, 39, 38, 40]
keydown (event) ->
  if event.which is L then lt 5
  if event.which is R then rt 5
  if event.which is U then fd 5
  if event.which is D then bk 5

Can't Touch This

t = write "<button>Touch This</button>"
t.speed Infinity
t.moveto document
t.mousemove (event) ->
  t.rt random(91) - 45
  while t.touches(event)
    t.bk 1

Magic Hat

defaultspeed Infinity
remove()
t = write '<img>'
t.home()
start = ->
  t.wear 'openicon:magic-tophat'
  tick off
  t.click (event) -> play()
play = ->
  t.wear 'openicon:animals-rabbit'
  tick ->
    t.moveto random 'position'
  t.click (event) -> start()
start()

21. Slicing

Color Slice

colors = [
    red, orange, yellow
    green, blue, purple]

speed 20
for end in [0..colors.length]
  for start in [0..end]
    dot black, 3
    fd 10
    rt 4
    for c in colors[start...end]
      dot c
      fd 10
      rt 4

Caesar Cipher

key = 13
a2z = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
rot = a2z[key...].concat a2z[...key]
box = write '<input>'
out = write ''

box.keyup ->
  result = for c in box.val()
    char = c.toUpperCase()
    if char in a2z
      rot[a2z.indexOf char]
    else
      char
  out.text result.join ''

Choices

choices = (menu, sofar = []) ->
  if menu.length is 0
    write sofar.join ' '
  else for item in menu[0]
    choices menu[1...],
      sofar.concat item

choices [
  ['small', 'medium', 'large']
  ['vanilla', 'chocolate']
  ['cone', 'cup']
]

22. Sorting

Quick Sort

list = (random 10 for x in [1..8])
list.sort()
write list

Slow Selection Sort

show = (points, highlight) ->
  render = for k, v of points
    if Number(k) in highlight
      "<mark>#{v}</mark>"
    else
      "#{v}"
  write "<div>#{render.join ','}</div>"

list = 'SORTME'.split ''
show list, []

for i in [0 ... list.length - 1]
  for j in [i + 1 ... list.length]
    if list[i] > list[j]
      [list[i], list[j]] =
        [list[j], list[i]]
    show list, [i, j]

Custom Quick Sort

sketch = (points) ->
  cg()
  pen null
  for p in points
    moveto p
    pen red
    dot black

array = []

button 'scatter', ->
  array = for x in [1..10]
    random 'position'
  sketch array

button 'sort',  ->
  array.sort (a, b) ->
    a.pageX - b.pageX
  sketch array

23. Search

Maze

[width, height] = [9, 9]
grid = table(width, height).home()

sides = [
  {dx: 0, dy: -1, ob: 'borderTop', ib: 'borderBottom'}
  {dx: 1, dy: 0, ob: 'borderRight', ib: 'borderLeft'}
  {dx: 0, dy: 1, ob: 'borderBottom', ib: 'borderTop'}
  {dx: -1, dy: 0, ob: 'borderLeft', ib: 'borderRight'}
]

isopen = (x, y, side) ->
  return /none/.test(
    grid.cell(y, x).css side.ob)

isbox = (x, y) ->
  return false unless (
    0 <= x < width and
    0 <= y < height)
  for s in sides
    if isopen x, y, s
      return false
  return true

makemaze = (x, y) ->
  loop
    adj = (s for s in sides when isbox x + s.dx, y + s.dy)
    if adj.length is 0 then return
    choice = random adj
    [nx, ny] = [x + choice.dx, y + choice.dy]
    grid.cell(y, x).css choice.ob, 'none'
    grid.cell(ny, nx).css choice.ib, 'none'
    makemaze nx, ny

wander = (x, y, lastdir) ->
  moveto grid.cell y, x
  for d in [lastdir + 3 .. lastdir + 7]
    dir = d % 4
    s = sides[dir]
    if isopen x, y, s then break
  turnto grid.cell y + s.dy, x + s.dx unless dir is lastdir
  direct -> wander x + s.dx, y + s.dy, dir

makemaze 0, 0
speed 5
wander 4, 4, 0

24. Intelligence

Tic Tac Toe

grid = table 3, 3,
  {width: 48, height: 48, font: "32px Arial Black", background: "wheat"}
grid.home()
board = [0, 0, 0,   0, 0, 0,   0, 0, 0]

grid.cell().click ->
  move = grid.cell().index this
  return unless winner() is 0 and board[move] is 0
  board[move] = 1
  $(this).text 'X'
  setTimeout respond, 500

respond = ->
  response = bestmove(-1).move
  if response?
    board[response] = -1;
    grid.cell().eq(response).text 'O'
  colorwinner()

bestmove = (player) ->
  win = winner()
  if win != 0 then return {move: null, advantage: win}
  choices = {'-1': [], '0': [], '1': []}
  for think in [0..8] when board[think] is 0
    board[think] = player
    outcome = bestmove(-player).advantage
    choices[outcome].push {move: think, advantage: outcome}
    board[think] = 0
  for favorite in [player, 0, -player] when choices[favorite].length
    return random choices[favorite]
  return {move: null, advantage: 0}

rules = [[0,1,2],[3,4,5],[6,7,8],[0,3,6],[1,4,7],[2,5,8],[0,4,8],[2,4,6]]

winner = ->
  for row in rules
    if board[row[0]] and board[row[0]] is board[row[1]] is board[row[2]]
      return board[row[0]]
  return 0

colorwinner = ->
  for row in rules
    if board[row[0]] and board[row[0]] is board[row[1]] is board[row[2]]
      for n in row
        grid.cell().eq(n).css {color: red}

Reference

Movement
fd 50	forward 50 pixels
bk 10	backward 10 pixels
rt 90	turn right 90 degrees
lt 120	turn left 120 degrees
home()	go to the page center
slide x, y	slide right x and forward y
moveto x, y	go to x, y relative to home
turnto 45	set bearing to 45 (NE)
turnto obj	point toward obj
speed 30	do 30 moves per second
Appearance
ht()	hide the turtle
st()	show the turtle
scale 8	do everything 8x bigger
wear yellow	wear a yellow shell
fadeOut()	fade and hide the turtle
remove()	totally remove the turtle
Output
p = write 'hi'	adds HTML to the page
p.html 'bye'	changes old text
button 'go', -> fd 10	adds a button with an action
read (n) -> write n*n	adds a text input with an action
t = table 3,5	adds a 3x5 <table>
t.cell(0, 0). text 'aloha'	selects the first cell of the table and sets its text
Other Objects
$(window)	the visible window
$('p').eq(0)	the first <p> element
$('#zed')	the element with id="zed"

Drawing
pen blue	draw in blue
pen red, 9	9 pixel wide red pen
pen null	use no color
pen off	pause use of the pen
pen on	use the pen again
mark 'X'	mark with an X
dot green	draw a green dot
dot gold, 30	30 pixel gold circle
pen 'path'	trace an invisible path
fill cyan	fill traced path in cyan
Properties
turtle	name of the main turtle
getxy()	[x, y] position relative to home
bearing()	direction of turtle
hidden()	if the turtle is hidden
touches(obj)	if the turtle touches obj
$(window). encloses(turtle)	true if the window encloses the turtle
Sets
g = hatch 20	hatch 20 new turtles
g = $('img')	select all <img> as a set
g.direct (j) -> @fd j * 10	direct the jth turtle to go forward by 10j pixels
Other Functions
see obj	inspect the value of obj
defaultspeed 8	set default speed
tick 5, -> fd 10	go 5 times per second
click -> fd 10	go when clicked
random [3,5,7]	return 3, 5, or 7
random 100	random [0..99]
play 'ceg'	play musical notes

Colors
white	gainsboro	silver	darkgray	gray	dimgray	black
whitesmoke	lightgray	lightcoral	rosybrown	indianred	red	maroon
snow	mistyrose	salmon	orangered	chocolate	brown	darkred
seashell	peachpuff	tomato	darkorange	peru	firebrick	olive
linen	bisque	darksalmon	orange	goldenrod	sienna	darkolivegreen
oldlace	antiquewhite	coral	gold	limegreen	saddlebrown	darkgreen
floralwhite	navajowhite	lightsalmon	darkkhaki	lime	darkgoldenrod	green
cornsilk	blanchedalmond	sandybrown	yellow	mediumseagreen	olivedrab	forestgreen
ivory	papayawhip	burlywood	yellowgreen	springgreen	seagreen	darkslategray
beige	moccasin	tan	chartreuse	mediumspringgreen	lightseagreen	teal
lightyellow	wheat	khaki	lawngreen	aqua	darkturquoise	darkcyan
lightgoldenrodyellow	lemonchiffon	greenyellow	darkseagreen	cyan	deepskyblue	midnightblue
honeydew	palegoldenrod	lightgreen	mediumaquamarine	cadetblue	steelblue	navy
mintcream	palegreen	skyblue	turquoise	dodgerblue	blue	darkblue
azure	aquamarine	lightskyblue	mediumturquoise	lightslategray	blueviolet	mediumblue
lightcyan	paleturquoise	lightsteelblue	cornflowerblue	slategray	darkorchid	darkslateblue
aliceblue	powderblue	thistle	mediumslateblue	royalblue	fuchsia	indigo
ghostwhite	lightblue	plum	mediumpurple	slateblue	magenta	darkviolet
lavender	pink	violet	orchid	mediumorchid	mediumvioletred	purple
lavenderblush	lightpink	hotpink	palevioletred	deeppink	crimson	darkmagenta

Turtle Bits

A Modern Programming Primer

David Bau