https://github.com/a1exxd0/hurtle

https://github.com/a1exxd0/hurtle

Last synced: 24 days ago
JSON representation

• Host: GitHub
• URL: https://github.com/a1exxd0/hurtle
• Owner: a1exxd0
• License: other
• Created: 2024-03-02T15:51:18.000Z (11 months ago)
• Default Branch: main
• Last Pushed: 2024-03-17T13:23:37.000Z (11 months ago)
• Last Synced: 2024-04-11T00:45:58.037Z (10 months ago)
• Language: Haskell
• Size: 453 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# CS141 Coursework 2 2024: Hurtle: The Haskell Logo Turtle

A language for drawing cool polygon art.

# Language rules

Specifying in more detail some syntactical rules:

 - Commas are treated as newlines

 - A HogoCode is a command that changes the active state of the program, i.e.

    - A movement or rotation (forward, back, right, left, home)

    - Pen command (setwidth, setcolor, penup, pendown, clearscreen)

    - Making a variable (make " )

    - Control flow calls:

        - Repeat: repeat \ [ \ ]

        - For : for [\ \ \ \] [ \ ]

        - Procedure calls : \ \

 - Multiple spaces and multiple newlines are parsed as a single space

 - HogoCode elements must end in a newline

 - Procedure declarations are not HogoCodes, they enclose HogoPrograms and only access what's in their scope

 - They are declared as: "to \ :\ :\ [ \ ] end" with an arbirary number of parameters.

 - Code is case-insensitive

 - A variable can be a float or a reference to another variable, or an operation performed on multiple variables

 - To use a variable, we can say for example: forward :\

 - We can perform arithmetic via keywords (sum, multiply, divide, difference)

 - In the fashion: \ \ \

## Example function and program

```

; where s, l, r, n, g, rp

to bam :s :l :r :n :g :rp [

    make "col 1 ;make a variable col the value 1

    repeat :rp [                    ; repeat this rp times

        make "col sum :col 1        ; add 1 to the value of col

        setcolor :col               ; set the color [truncates the value in interpretation for type safety]

        setwidth multiply :col 1.01 ; set the width and expand slowly

        right :r                    ; rotate right by parameter

        repeat :s [                 ; repeat s times by parameter

            forward :l              ; move forward l by param

            right div 360 :s        ; go right by 360 div param

        ]                           ; scope repeat close

        make "l sum :l :n           ; make l the sum of 2 params

        right :r                    ; go right by param

        make "s sum :s :g           ; make s the sum of 2 params

    ] 

] end

bam 5 100 3 5 0 420

```

# Fail cases

The program isn't perfect (and neither is Logo Turtle, this mimics that in a sense)

 - If you write a program that won't terminate, the code is guaranteed to never run.

 - The compiler relies on knowing exactly how many calls are made as loops are replaced with the code equivalent; i.e. writing repeat 2 \ will replace that HogoCode with \ \. A similar process is applied to for loops

 - The conditional for loop is not affected by change of variable inside of the loop, i.e. if you set step to 1 and add 1 to the counter variable inside of the loop, it won't loop fewer times.