Basic Syntax

Numbers

Numebrs in lox are double-precision floating point numbers by default. Addition / Subtraction / Multiplication and Division is supported natively.

Strings

Strings in lox are to be enclosed in double-inverted commas. String concatenation is supported through the + operator

Example

var a = "Hello ";
var b = "World";

var c = a + b; // c contains "Hello World"

Variables

Variables are declared and assigned with the following syntax

var <variable_name> ;
var <variable_name> = <expresssion>;

Example

var a;
var b = 16;

Until the value of the variable is intialized, it holds the value nil

Warning

Note : Redeclaring variables is only allowed in the global scope. Any attempt to redeclare variables in a local scope will lead to an error.

Assignment

Variable assignnments are considered to be expressions by lox and thus return the value that is being assigned. This allows for chained assignment.

Example

var a;
var b;
var c;

c = b = a = 5;

Booleans

Booleans in lox are denoted by true and false.

Truthiness

In lox only nil and false are Falsy values. Every other value is considered to be Truthy.

Example:

if (12)
{
    print "Yes"; 
} 
// Yes

If-else statements

Syntax

if (<condition>)
{
    <statements>
}
else
{
    <statements>   
}

If the block has only one statement, the braces can be ommitted.

Example

if (18 >= 7)
{
    print "larger";
}
else print "smaller";

Ternary

Lox provides inline support for branching statements through the ternary operator.

Syntax

condition ? expression1 : expression2

Example

var a = 16 > 2 ? 5 : 7;

Print

Lox allows outputting outside the program through print.

Syntax

print <expression>;

Example

print "Hello World";    

Comments

Single line comments begin with // and multiline comments can be enclosed in /* and */.