2. Program Structure

LiteScript programs follow a certain structure to ensure a correct and predictable execution flow, defining a set of rules that each program needs to follow.

2.1 Relevant Keywords

For defining the program structure, along with any modules and external dependencies, there is a set of keywords that all work together to make a LiteScript program executable.

• The "start" keyword

start

Denotes the global entry point for a LiteScript program (just like the main function in many languages), this is where interpreter starts executing code. It works just like a function, having a special reserved keyword for it.

The start keyword must be located in the file that is directly being called by the interpreter, not doing so may result in undefined behavior.

Any arguments passed when calling the interpreter will be available here.

• The "import" keyword

import [module1] [module2] ...

Imports and activates any of the available modules integrated into the interpreter, allowing their special module functions to be available for use. Any module imports referenced in external dependencies will also be included, if they are multiple imports of a same module, it is not imported more than once.

You can put import statements on any line, but it is best practice to put them at the top of the file.

You can import modules either on the same import statement, or in multiple:

import module1 module2

import module1
import module2

• The "require" keyword

require [file1] [file2] ...

There's a separate keyword for including/importing other LiteScript files, which we call external dependencies. Groups together all the functions, module imports and external dependencies and "intuitively" pastes them into the same file, making all the functions and modules in the require chain available, if they are multiple imports of a same file, it is not imported more than once.

You must provide an absolute or relative path to a filename, or just the filename if it is in the same working directory as the context where you are calling the interpreter, otherwise it will result in a parsing stage error.

You can put require statements on any line, but it is best practice to put them at the top of the file.

You can import files either on the same require statement, or in multiple:

require file1 file2

require file1
require file2

2.2 Indentation and Scoping

Like Python, LiteScript depends on strict indentation with true tabs to represent different scopes or blocks of code, if true tabs aren't used then the program can't run correctly. In the repository, you can find a VSCode extension that (along with syntax highlighting) insures that when you hit tab, then always only true tabs are inserted instead of spaces, correctly using indentation.

Different levels of indentation indicate different scopes, variables that go out of scope are effectively erased and need to be redeclared if used again. Scopes are used in function definitions (including the start keyword) and in control flow statements.

Unlike in other dynamic scripting languages, the global scope is non-existent in LiteScript, and lines with no indentation (indentation level zero), are reserved exclusively for import and require statements, function names, and the start keyword.

start
	Scope 1

	Control flow statement
		Scope 2
		
		...
	
	Back to Scope 1

2.3 Program Template

With all the previous rules set, we provide the following template used recurringly across almost all LiteScript programs, which can be used as a standard for best practices:

import ...
require ...

FUNCTION1
    ...

...

start
    ...

With all declarative statements defined at lines with no indentation (indentation level 0), and all procedural code starting with indentation (indentation level 1+).