https://github.com/aneilmac/worldturtle-haskell

LOGO-like Turtle Graphics in the Haskell language using Monads.
https://github.com/aneilmac/worldturtle-haskell

haskell logo monad simulation teaching turtle turtle-graphics

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LOGO-like Turtle Graphics in the Haskell language using Monads.

• Host: GitHub
• URL: https://github.com/aneilmac/worldturtle-haskell
• Owner: aneilmac
• License: bsd-3-clause
• Created: 2020-05-21T01:02:29.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2022-04-03T19:55:44.000Z (almost 3 years ago)
• Last Synced: 2024-12-30T18:56:59.342Z (about 1 month ago)
• Topics: haskell, logo, monad, simulation, teaching, turtle, turtle-graphics
• Language: Haskell
• Homepage:
• Size: 2.04 MB
• Stars: 4
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# WorldTurtle [![Hackage][Hackage badge]][Hackage page]

## Turtle Animations in Haskell

WorldTurtle is a Haskell take on [Turtle Graphics][Turtle graphics wiki].

The intent of this module is a teaching tool by using turtle commands to

produce animations.

![parallel circles animation](worldturtle/docs/images/parallel_circles_animated.gif)

## Features

### Monadic commands

Turtle commands are monads!

The following snippet produces a square:

```haskell

import Graphics.WorldTurtle

main :: IO ()

main = runTurtle $

  repeatFor 4 $ do

    forward 90

    right 90

```

Like so!

![turtle drawing a square](worldturtle/docs/images/basic_turtle_square.gif)

 

### Parallel animations

Use of the parallel animation operator `(>!>)` allows animations to run in

parallel. The

  [parallel/serial comparison](worldturtle-examples/parallelserialcomparison/Main.hs)

example shows that when given this code:

```haskell

import Graphics.WorldTurtle

main :: IO ()

main = runWorld $ do

  turtle1 <- makeTurtle' (0, 0) north green

  turtle2 <- makeTurtle' (0, 0) north red

  -- Draw the anticlockwise and clockwise circles in sequence. 

  (turtle1 >/> circle 90) >> (turtle2 >/> circle (-90))

  

  clear

  -- Draw the anticlockwise and clockwise circles in parallel.

  (turtle1 >/> circle 90) >!> (turtle2 >/> circle (-90))

```

We get this animation:

![serial vs parallel comparison](worldturtle/docs/images/parallel_serial_turtles_2.gif)

### Interactive Controls

You can interact with the animation window in the following ways:

| Action                                  | Interaction        |

|-----------------------------------------|--------------------|

| Pan the viewport.                       | Click and drag     |

| Zoom in/out.                            | Mousewheel up/down |

| Reset the viewport to initial position. | Spacebar           |

| Reset the animation.                    | `R` key            |

| Pause the animation.                    | `P` key            |

| Quit                                    | Escape key         |

## Examples

For all examples, look [here](worldturtle-examples)!

### [spiralstar](worldturtle-examples/spiralstar/Main.hs) example

![spiralstar animation](worldturtle-examples/spiralstar/output.gif)

### [spiralsquare](worldturtle-examples/spiralsquare/Main.hs) example

![spiralsquare animation](worldturtle-examples/spiralsquare/output.gif)

### [lsystem](worldturtle-examples/lsystem/Main.hs) example

![lsystem animation](worldturtle-examples/lsystem/output.gif)

## Building a project

### Prerequisites

To build this project you need `stack` and `ghc`. If you don't

already have these, then you can install them easily from the

[Haskell Platform](https://www.haskell.org/platform/)!

#### Windows

If you get this error on startup:

> user error (unknown GLUT entry glutInit)

Then this means you need the `freeglut MSVC` binaries which you can get

[here](https://www.transmissionzero.co.uk/software/freeglut-devel/).

Extract `freeglut\bin\x64\freeglut.dll` to the same location as the executable

you wish to run, or place it in a folder that can be discovered by your `%PATH%` variable.

([Here are some steps](https://docs.alfresco.com/4.2/tasks/fot-addpath.html) on how to add a new folder to your `%PATH%`.)

### Making a new turtle project from a template

Using stack, you can create your own `worldturtle` project by using the provided

template.

To create and run your own project, use the following commands to get setup:

```sh

stack new my-new-project aneilmac/worldturtle

cd my-new-project

stack build

stack exec my-new-project

```

## Building and running examples

Examples can be built via [stack](https://docs.haskellstack.org/en/stable/README/).

```sh

stack setup

stack build

```

After building, examples in the `worldturtle-examples` folder can then be

executed from stack. To run `parallelcircles` try:

```sh

stack exec parallelcircles-exe

```

[Hackage page]: https://hackage.haskell.org/package/worldturtle

[Hackage badge]: https://img.shields.io/hackage/v/worldturtle

[Turtle graphics wiki]: https://en.wikipedia.org/wiki/Turtle_graphics

## Transcoding from LOGO to WorldTurtle

See [here](LOGOTRANSCODE.md) for a detailed description on porting LOGO code to WorldTurtle.