Kara — Grid World Guide

Kara is a ladybug that lives in a grid world. She can move, turn, pick up and place leaves, and push mushrooms. Trees block her path.

The <kara-editor> component is a variant of <bottom-editor> (Documentation →)tailored for Kara programs: no imports needed, animated step-by-step execution, and a compact console showing only error messages.

Source: github.com/tkilla77/python_editor_wasm · Original Kara (SwissEduc)

Quick start

<script type="module" src="https://bottom.ch/editor/stable/kara-editor.js"></script>

<kara-editor>
<kara-world>
#########
#...>...#
#########
</kara-world>
kara.move()
kara.move()
kara.turnLeft()
</kara-editor>

######### #...>...# ######### kara.move() kara.move() kara.turnLeft()

The world

Define the world inside a <kara-world> child element using a simple text grid:

Character	Meaning
`#`	Tree (also used for borders)
`T`	Tree (inside the grid)
`>`	Kara facing right
`<`	Kara facing left
`^`	Kara facing up
`v`	Kara facing down
`L`	Leaf
`M`	Mushroom
`.`	Empty cell

If no <kara-world> is given, a default empty grid is used.

Commands

Command	Description
`kara.move()`	Move one step in the current direction
`kara.turnLeft()`	Turn 90° counter-clockwise
`kara.turnRight()`	Turn 90° clockwise
`kara.putLeaf()`	Place a leaf on the current cell
`kara.removeLeaf()`	Pick up the leaf on the current cell

await is inserted automatically — just write kara.move(), not await kara.move().

Sensors

Sensor	Returns
`kara.treeFront()`	`True` if there is a tree directly ahead
`kara.treeLeft()`	`True` if there is a tree to the left
`kara.treeRight()`	`True` if there is a tree to the right
`kara.mushroomFront()`	`True` if there is a mushroom directly ahead
`kara.onLeaf()`	`True` if Kara is standing on a leaf

Mushrooms

Kara can push a mushroom if the cell behind it is empty or has a leaf. Pushing into a tree or another mushroom raises a KaraException.

########## #..>M....# ########## kara.move() kara.move() kara.move()

Sensors example

########## #>......T# #........# ########## while not kara.treeFront(): kara.move() if kara.onLeaf(): kara.removeLeaf() else: kara.putLeaf()

Attributes

Attribute	Default	Description
`step`	`200`	Animation delay between steps in milliseconds; `0` for instant
`autorun`	off	Run the program automatically when Pyodide is ready
`timeout`	`30`	Maximum run time in seconds; `inf` to disable

Labyrinth Example

TTTTTTTTTTTTTTTTTT T> T TTTTTTTTTTTTTTTT T T T T TTT TTTTTTTTTTTT T T T TTTTTTTT TTTTTTTTT T T T TTT TTTTTTTTTTTT T T T TTTTTTTT TTTTTTTTT T T T TTT TTTTTTTTTTTT T T T TTTTTTTT TTTTTTTTT T T TTTTTTTTTTTTLTTTTT while not kara.onLeaf(): if not kara.treeRight(): kara.turnRight() kara.move() elif not kara.treeFront(): kara.move() else: kara.turnLeft()

Exceptions

When Kara cannot execute a command, a KaraException is raised:

Tree blocking the path! — kara.move() would walk into a tree or boundary
Cannot push mushroom — blocked! — the cell behind the mushroom is occupied
Already a leaf here! — kara.putLeaf() on a cell that already has a leaf
No leaf here! — kara.removeLeaf() on an empty cell

The exception message is shown in the console panel below the world.