Booleans

The Boolean type (bool) represents a truth value — either TRUE or FALSE.

• Neutral literal: FALSE
• typeof result: 'bool'

Creating booleans

Booleans are typically produced by comparison operations, type checks, or explicit commands:

XML

<!-- Explicit boolean values -->
<true var="flag" />    <!-- TRUE -->
<false var="flag" />   <!-- FALSE -->

<!-- Cast from other types -->
<set var="x">1</set>
<cast var="x" type="bool" />  <!-- TRUE -->

true | false | cast

Truthiness rules

Different values convert to boolean as follows:

Value	Boolean equivalent
undefined	FALSE
NULL	FALSE
FALSE	FALSE
TRUE	TRUE
0 (int)	FALSE
0.0 (float)	FALSE
Any other number	TRUE
'' (empty string)	FALSE
'0' (string zero)	FALSE
Any other string	TRUE
Any array	TRUE

note

The string "0" is falsy when cast to boolean — this catches many developers off guard. Always use explicit type checking with is or typeof when the distinction matters.

Booleans in conditionals

The <if> construct compares two values with a comparison function — it does not directly evaluate boolean truthiness. To check if a variable is truthy, compare it against an empty string:

XML

<if value1="$flag" func="!=" value2="">
    <output>flag is truthy</output>
</if>

For type-based branching, use is:

XML

<is var="x" type="bool">
    <output>x is a boolean</output>
</is>

Boolean to string

When cast to string, TRUE becomes "1" and FALSE becomes "" (empty string). This matters when outputting boolean values:

XML

<true var="flag" />
<output>Flag: $flag</output>
<!-- Flag: 1 -->