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LANGUAGE.md

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Drawson Language Documentation

The drawson language is quite a simple one. There are just a few instructions which makes it quite simple to get started.

Core Statements

draw

draw statement is used to draw an unfilled shape. There are 3 legal shapes for this directive:

  • circle - draws unfilled circle on canvas. Takes in 3 arithmetic arguments separated by space, first two are coordinates of center of the circle, 3rd one is the radius of the circle.
  • rect - draws unfilled rectangle on canvas. Takes in 4 arguments. First two are coordinates of top left corner of rectangle, 3rd is width, and 4th is height of the rectangle.
  • line - draws line. Takes in 4 arguments coordinates of first pint of the line, and then coordinates of end point of rhe line.

fill

fill statement is used to draw filled shape. There are 2 legal shapes for fill statement:

  • circle - draws filled circle on canvas. Takes in 3 arithmetic arguments separated by space, first two are coordinates of center of the circle, 3rd one is the radius of the circle.
  • rect - draws unfilled rectangle on canvas. Takes in 4 arithmetic arguments. First two are coordinates of top left corner of rectangle, 3rd is width, and 4th is height of the rectangle.

set

set statement is used to set context variables value. There are 3 context variables that can be set:

  • thickness this variable requires arithmetic value (basically a number, or expression which outcome is a number), it is used to determine thickness of unfilled shapes borders.
  • paint is a variable that defines color of fill of fillable shapes. Requires hex color variable like #FFFFFF
  • color is a variable that defines color of border of unfillable shapes. Requires hex color variable like #000000

let

let is used to define global arithmetic variables. Variables can be delcared, assigned and declared with direct assignment. When youd eclare a variable without assignment then underneath our drawing engine will receive null somewhere.

examples:

let a = 12;
let b;
b = 2+2 *2;
b = 22;

for

for is a loop keyword. It enables developer to define a loop on a given range of numbers that is growing by 1. eg range 1..5 is actually equivalent to looping on an array of [1,2,3,4,5].

The syntax is relatively simple, for [iteratingVarName] in [range] [blockOfCode] Example to grasp what it actually is:

for element in 10 100 {
    draw rect 0 0 10 10;
    fill rect 0 0 10 10;
}

while

while is another loop type here we actually can use boolean expressions (there are no if statements yet but we may implement).

Syntax is simple as well, while ([booleanExpression]) [blockOfCode]

Example of this syntax:

let a = 0;
while (a < 20) {
    draw line 0 0 a a;
    a = a + 1;
}

Just don't do infinite loops at this time, cause i didn't implement any detectors of infinite loops, might do that later though, but right now you are going to have a bad time, chrome will probably run out of memory.

Other atomic Statements

Arithmetics

Arithmetic value which was mentioned before is an expression that represents an integer, there are no floating point values.

To get an expression that resolves to integer there are n possibilities:

  • value literals like 123;
  • variable that holds an integer like let a = 12, then when you reference a it resolves to value 12
  • arithmetic using above. We support 4 operations +, -, *, /. You know what they mean. There actually is also a support for correct order of arithmetics including parentheses, and negative values (but for negative values, because we separate arguments with spaces, you need to wrap them in parentheses).

Conditionals, bool algebra

We support this for the sake of while loops. There are 3 operations:

  • && and opoerator
  • || or operators
  • ! operator

Those operators require some values that resolve to boolean true or false. Following resolve to them:

  • literal like true or false
  • relative comparing operator on arithmetic values, exmplained below

Relative operators

In order to obtain some boolean value you can compare arithmetic values. There are 6 of operators here:

  • < less than
  • > greater than
  • <= less or equal than
  • >= greater or equal than
  • == equal to
  • != not equal to