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Grammar and types

This chapter discusses Quackscript's basic grammar, variable declaration, data types and literals.

Basics​

In Quackscript each statement must end with a 🦆

Comments​

A comment in quackscript start with // until the end of the line. Comments are not executed, they exist to annotate your code. It is good practice to explain complex parts of your code with comments.

// this is a comment

You can also write a multiline comment by starting with /* and ending with */

/*

this is a multiline comment

*/

Declarations​

Quackscript supports two types of declarations.

quack Declares a variable.

QUACK Declares a read-only constant which can't be changed.

Declaration and initialization​

All variables must be declared before they are used, otherwise an exception is thrown.

You can use quack and QUACK to declare block-scoped variables. (See variable scope below.)

To declare a variable you use the following syntax:

quack a🦆

A variable can be initialized and declared on the same line using the following syntax:

quack a <- 'hello world'🦆

A constant must always be initialized when declared.

QUACK a <- 'hello world'🦆

Variable scope​

In quackscript variables belong to the global scope or the code block.

A code block is defined as a pair of { }

quack a <- 'hello world'🦆

QUACK b <- () {
    QUACK c <- 32🦆
    a <- 'bye world'🦆
}🦆

On the example above. The variable a is on the global scope, which means is accessible anywhere on this file. Variable c is declared inside a code block which means it is only accessible inside such code block. Variables are deleted from memory after the block execution is finished so after the execution of the function b the variable c is no longer in memory and a has been changed to 'bye world'.

Data types​

Quackscript provides the following data types:

  1. boolean - true and false.
  2. nothing - A data type which denotes the lack of a value. Non initialized variables will contain nothing and non returning functions will return nothing
  3. number - An integer or floating point number. Eg. 32 or 32.5
  4. text - A sequence of characters. Eg. 'Hello World'
  5. function - A function definition
  6. object - [not implemented]
  7. list - [not implemented] A sequence of same type elements
  8. vector2 - [not implemented] A 2 dimensional vector containing x and y number values
  9. vector3 - [not implemented] A 3 dimensional vector containing x, y and z number values
  10. dictionary - [not implemented] A collection of key value pairs where each key is unique and of the same type

Variable typing​

Every variable will have a type associated with it. You can explicitly define the type after the variable name or let quackscript infer the type for you.

QUACK a:text <- 'hello world'🦆

// this will generate the same typed variable as above
// quackscript infers the type from the initialization
QUACK b <- 'hello world'🦆

Quackscript is a strongly static typed language which means once a variable type is defined you can no longer assign a value of a different type

quack a:text <- 'hello world'🦆

// The following statement will throw an error
a <- 23🦆

A variable can be optional which allows it to be the typed value or nothing. You can declare a variable as optional by adding a ? after the variable identifier

quack couldBeNothing?:string🦆
// At this point 'couldBeNothing' is 'nothing'

couldBeNothing <- 'hello world'🦆
// At this point 'couldBeNothing' is 'hello world'