Functions and Constants
Reference built-in runtime constants, state management stores, visualization controls, and transparent bridges to standard PHP and WordPress utility functions.
Rather than maintaining static reference pages for hundreds of standard PHP and WordPress functions, Expression Lab features live runtime introspection. You can browse, search, and inspect complete parameter signatures, return types, and documentation in the Sidebar Outline Explorer and inline tooltips inside the REPL console.
Runtime Constants
Constants in Expression Lab are immutable values registered in the expression execution context. They can be referenced by name without any dollar sign ($) or special prefix.
Top-Level Engine Constants
Top-level constants are globally accessible within any expression:
| Constant | Type | Description | Example |
|---|---|---|---|
EXPRESSION_LAB_VERSION | string | Returns the currently active Expression Lab plugin version string. | EXPRESSION_LAB_VERSION |
/* Check current engine version */
'Running Expression Lab v' ~ EXPRESSION_LAB_VERSION
Service & Object Scoped Constants
Services and domain models expose specific operational constants through object dot-notation:
/* Example of an Options service constant */
Options.FORMAT_JSON
/* Example of an Http service constant */
Http.ALLOWED_OPTIONS
Constants used to configure the host plugin environment, such as EXPRESSION_LAB_MAX_EXECUTION_LIMIT or EXPRESSION_LAB_DATABASE_READONLY, are native PHP constants configured in wp-config.php. See the Configuration guide for complete documentation.
State Management & Special Forms
Variable storage, multi-step sequencing, anonymous lambda closures, and higher-order stream transformations are powered by native engine Special Forms (set[...], var[...], isset[...], unset[...], show[...], prog[...], fn[...], map[...], filter[...], reduce[...]).
Special forms are built into the Abstract Syntax Tree parser using bracket syntax (keyword[...]) rather than parenthesized function calls (function(...)).
For comprehensive documentation on declaring variables, creating closures, and executing multi-step workflows, see the Scripting Syntax Guide.
PHP & WordPress Function Bridges
Expression Lab registers curated sets of native PHP and WordPress helper functions into the expression language namespace. These functions can be called natively like any standard expression function:
/* Native PHP string and array functions */
strtoupper(trim(' hello world '))
json_encode({ status: 'ok', count: 42 })
/* Native WordPress helper functions */
wp_strip_all_tags('<p>Sample Text <a href="#">Link</a></p>')
To explore all registered PHP and WordPress functions, open the Sidebar Outline Explorer in the REPL console, where every function is listed with interactive documentation, parameter types, default values, and links to official documentation.