Syntax & Semantics

Script or Tags? Choose wisely!

There are two ways to write BoxLang code: in tag or in script syntax. BoxLang will dictate that your view or presentation layers will utilize the tag syntax in bxm files and the script syntax in bxs and bx files. Please note bx files are specifically for Box Classes, this is where model or business layers should all be done. (MVC comes later). There are no differences in functionality between them; it's pure syntax.

In BoxLang tags start with bx: vs cf. So instead of <cfoutput> use <bx:output>.

Syntax Files

BoxLang includes a set of instructions you use on pages (.bxm,.bxs) or classes (.bx). You will write one or more instructions in a file (.bxm,.bxs,.bx) then run the file through a BoxLang engine or Command Line Interpreter like CommandBox.

  • bxm - BoxLang markup file, tag syntax is the default and used for views

  • bxs - BoxLang script file, script syntax.

  • bx - The default is the BoxLang class file (Class or Object), script syntax.

Implicit Behavior

BoxLang also gives you a pre-set of defined components and functions available to you in any file you write your code in. These tags and functions allow you to extend the typical language constructs with many modern capabilities, from database interaction to PDF generation. They are basically automatic imports.

Tip: Please note that the BoxLang built-in functions are also first-class functions so that they can be passed around as arguments to other functions or closures or saved as variables.

Exploring Behavior

Three BoxLang instructions we will use in this section are bx:set, bx:output, and bx:dump.

  • bx:set is used to create a variable and assign it a value.

  • bx:output displays a variable's value to the output stream.

  • bx:dump is used to display the contents of simple and complex variables, objects, classes, user-defined functions, and other elements to the output stream.

We might have a file named myprogram.bxm and Sample.bx like this:

Tag Syntax

<bx:set s = new Sample()>

Script Syntax

    s = new Sample();
    writeOutput( s.hello() );

Tip: Please note that if you want to write in script in a tag-based file, you must use an opening and closing <bx:script> tag.


    function hello(){
       return "Hello, World!";


Please note that no types and not even any visibility scopes you might be used to are present. BoxLang can also infer variable types on more distinct variables like dates, booleans, or numbers. However, please note that you can fully leverage types if you like:


    public string function hello(){
       return "Hello, World!";


By default, the return type of every function and/or argument is any. Thus, it can be determined at runtime as a dynamic variable.


Please note that semi-colons are used to demarcate line endings in BoxLang ;. They can be optional, however. Also, note the CommandBox REPL does NOT require semi-colons.

Tags In Script

BoxLang will allow you to write your tags in script syntax. You basically eliminate the starting < and ending > enclosures and create a block by using the { and } mustaches.

BoxLang uses Lucee's generic tag-in-script syntax

http method="GET" charset="utf-8" url="" result="result" {
    httpparam name="q" type="formfield" value="test";

Polyglot References

As we now live in a world of polyglot developers, we have added references below to other languages to see the differences and similarities between BoxLang and other major languages in usage today. Please note that this section is merely academic and to help developers from other language backgrounds to understand the intricacies of the BoxLang syntax.

PHP Syntax

    $s = new Sample();
    echo $s->hello();
class Sample
    public function hello() {
        return "Hello, World!";

Ruby Syntax

class Sample
    def hello
        "Hello, World!"

s =
puts s.hello

Java Syntax

public class MyProgram {

    public String hello(){
        return "Hello, world!";

    public static void main(String[] args) {
        System.out.println( new MyProgram().hello() );


Coding Standards

At Ortus Solutions, we have developed a set of development standards for many languages. You can find our BoxLang standards here:

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