Hello World

Creating Your First Script

RHP files use either the .rhp extension (recommended for standalone projects) or .php (for gradual drop-in upgrades).

Create a new file named hello.rhp:

// Declare typed variables
string $target = "World";

// Utilize native Rust-backed string facades
string $message = Str::slug("Hello " . $target . " from RHP Engine");

// Standard library output intrinsic
print("Output: " . $message); //automatically compiled to Sys::print()
print("RHP Version: " . Sys::version()); //automatically compiled to Sys::print()

Automatic Global Function Compilation: In RHP, opening script tags are not used — files directly begin with statements. The Pratt parser and AST compiler statically resolve and compile global functions:

• System Intrinsics: Calls to print(), env(), and dd() are automatically lowered to Sys::print(), Sys::env(), and Sys::dd().
• PHP Global Functions: Global functions of PHP are automatically compiled into Glob::helperFunctions (such as Glob::customHelper() and static facade dispatches). This eliminates global namespace lookup overhead and delivers zero-cost direct dispatch while retaining familiar PHP syntax.

Executing in Development Mode

During development, you want instantaneous startup and clear stack traces. If your entry script is named index.rhp in the current working directory, simply execute rhp run dev:

# Automatically picks index.rhp in current working directory
rhp run dev

# Or pass a specific file via --file argument
rhp run dev --file="hello.rhp"

# Or pass as a positional argument
rhp run dev hello.rhp

Output:

Output: hello-world-from-rhp-engine
RHP Version: 0.1.0

How it works: Development Mode uses a direct tree-walking AST interpreter. It evaluates parse tree nodes directly in memory without emitting bytecode or waiting for JIT compilation, delivering cold startup times under 5 milliseconds.

Executing in Production Mode

When deploying high-throughput microservices or running CPU-intensive algorithms, execute via rhp run build:

# Automatically picks index.rhp in current working directory
rhp run build

# Or pass a specific file via --file argument
rhp run build --file="/your-path/server.rhp"

# Or pass as a positional argument
rhp run build hello.rhp

How it works: Production Mode lowers the parsed AST into a register-based Bytecode Intermediate Representation (IR) and activates Cranelift JIT compilation on hot loops, running inside a Tokio multi-threaded worker pool.

Running Interactive Web Applications (HTMX & Alpine.js)

When building web applications with interactive frontends and HTTP routing, RHP automatically starts an HTTP web server on port 8080:

# Run the built-in reactive TODO example app
rhp run dev examples/todo

# Or using the dev shorthand
rhp dev examples/todo

Terminal output:

=======================================================================
🚀 RHP Development Server (Dev Mode)
📡 Listening on: http://127.0.0.1:8080
📂 Serving application: examples/todo/index.rhp
⚡ Reactive UI: HTMX + Alpine.js
⌨️  Press Ctrl+C to terminate the server.
=======================================================================

Open http://localhost:8080 in your browser to interact with the application.

Auto-Formatting and Linting

RHP includes a built-in code formatter and type annotator inspired by Carthage Software Mago:

rhp run lint hello.rhp

The linter automatically:

1. Enforces standard 4-space indentation and normalizes operator spacing.
2. Formats identifiers according to RHP conventions ($snake_case for variables, PascalCase for classes, camelCase for methods).
3. Infers and prepends variable type hints where omitted.