A Roy programming/learning environment with Turtle Graphics, as in the Logo programming language.
Try it online: turtle-roy.heroku.com/
| Command | Result |
|---|---|
| fd 100 | moves 100 pixels forward |
| lt 45 | turns left 45 degrees |
| rt 90 | turns right 90 degrees |
| penup | lifts the pen, no trace left when moving |
| pendown | lowers the pen again for drawing |
| setshape "rocket-large" | changes the cursor. available (with and without -large): butterfly, car, fairy, formula, princess, rocket, turtle |
| clear | clear the paper and reset turtle to center |
| home | reset the turtle to center |
| say "wat" | speak! |
| print "x" | print to console |
| login "raimo" | login as "raimo" (this is the author name in your saved work) |
| save "asdf" | save current work as "asdf" |
| open "asdf" | open saved work "asdf" (presuming you've saved with this name and current author name) |
| whoami | show the author name of the logged-in user (this is just saved in a cookie) |
| ls | list your saved works |
| play c | plays the note C |
| play c 500 | plays the note C for 500 milliseconds (half a second) |
| play c*2 | plays the note C2 (frequency = C * 2) |
| pause | pauses for a while |
| pause 1000 | pauses for 1000 milliseconds (1 second) |
| sequence [fd 100, rt 90] | 100 pixels forward, then right turn |
| s [fd 100, rt 90] | same as above |
| repeat 4 (say "hello") | says "hello" 5 times |
| r 4 (say "hello") | same as above |
| par [play c, play e] | playes notes C and E in parallel |
| bg "red" | change background color (red, rgb(255,0,0), #FF0000) |
| color "red" | change pen color (red, rgb(255,0,0), #FF0000) |
| text "HELLO" | draw the text "HELLO" beside the turtle |
| font "40px Arial" | changes to the 40px Arial font |
| font 100 | changes to the 100px Courier font |
| Example | Result | Description |
|---|---|---|
| range 1 3 | [1,2,3] | range of numbers |
| length [1,2,3] | 3 | list length |
| empty [1] | false | is list empty |
| concat [1,2] [3] | [1,2,3] | concatenate lists |
| cons 1 [2,3] | [1,2,3] | prepend to list |
| head [1,2] | 1 | first item on list |
| tail [1,2,3] | [2,3] | all but first item on list |
| last [1,2] | 2 | last item on list |
| times 2 "yes" | ["yes", "yes"] | repeat same element |
| sum [1,2,3] | 6 | sum of items on list |
| map (\x -> x * 2) [1,2] | [2,4] | map list items with function |
| filter (\x -> x ==1) [1,2] | [1] | filter list with function |
| zip plus [1,2] [3,4] | [4,6] | zip lists pairwise with function |
| scanl plus 0 [1,2,3] | [0,1,3,6] | accumulate values, output all |
| foldl plus 0 [1,2,3] | 6 | accumulate values, output last |
In addition to this, you may use the full Roy programming language.
Bunch of examples available in the demo menu. Some more stuff here.
Basic Turtle commands
fd 100
lt 90
rt 45
Square
let square = repeat 4 (sequence[fd 50, lt 90])
square
Flower
let flower = repeat 36 (sequence[rt 10, square])
flower
Math
3 + 4
3 / 4
let factorial n = if n==1 then 1 else n * (factorial n - 1)
factorial 12
Strings
"apple" ++ "sauce"
"apple" + 10 (won't compile)
Lists
range 1 99
times 100 "lol"
head [1,2,3]
tail [1,2,3]
concat [1,2,3] [4,5,6]
length [1,2,3]
empty []
let reverse xs = if (empty xs) then [] else concat (reverse (tail xs)) [head xs]
reverse [1,2,3]
sum [1,2,3]
map (\x -> x * 2) [1,2,3]
filter (\x -> x > 1) [1,2,3]
foldl (\x y -> x * y) 1 [1,2,3]
You can export your drawing as a series of commands in JSON format by opening your browser's
developer console and typing turtle.export().
Build (and rebuild on javascript changes)
npm install
Install mongodb
brew install mongo
Run the server (node.js / express)
./runmongo
./server
And
open http://localhost:8070
To build client-side code on every change, just
npm run watch
Thanks to Miikka "arcatan" Koskinen for creating tryroy, from where I shamelessly stole the Roy browser REPL.
Thanks to Brian McKenna for the Roy language and support.
See origins of the cursor images from src/main/webapp/images/image-sources.txt