mod_wren

mod_wren is an Apache server module which embeds the scripting language Wren (GitHub). The module supports all of Wren's usual features, along with a small set of functions for standard server-side programming such as parsing GET/POST requests, getting and setting cookies, and database interaction.

Writing Wren pages

mod_wren allows Wren code and expressions to be interleaved with HTML on pages with the extension .wrp:

<!DOCTYPE html><?wren

import "random" for Random

var random = Random.new()
?>
<html>
	<body>
		<h1>Random numbers</h1>
		<div>Your random number: <%= random.float() %></div>
	</body>
</html>

Files with the standard .wren extension can run plain Wren code:

/**
 * Read a number from the GET parameter 'count' and return a JSON array of
 * that many random floats.
 */
import "random" for Random

Web.setContentType("text/json")
Web.setStatusCode(200) /* 200 is the default. */

var numbers = []
var random = Random.new()
var getParams = Web.parseGet() || {}
var count = Num.fromString(getParams["count"] || "") || 0

for(x in 0 ... count) numbers.add("\"%(x)\":%(random.float())")
System.write("{" + numbers.join(",") + "}")

Building

mod_wren is currently only supported on Linux, tested on Debian 9 (Stretch), and depends on having mod_dbd enabled. To build and install:

git clone https://github.com/azufluup/mod_wren
cd mod_wren
make
make install # Requires privileges in /etc/apache2

Building requires an internet connection to clone the Wren repo.

Running

Add the following lines to your Apache configuration (e.g. /etc/apache2/apache2.conf) to tell mod_wren to handle .wren and .wrp files:

LoadModule wren_module modules/mod_wren.so

<FilesMatch "\..*(wren|wrp)$">
	SetHandler wren
</Files>

If you want index.wrp files to be considered as potential resources for directory indexes, you can also add:

DirectoryIndex index.wrp index.html

Error reporting

Any errors in your Wren program will display as on the page, indicating the problematic module and line number. This can be disabled in your Apache config with the directive ModWrenErrors 0.

Wren makes meaningful use of newlines to close statements. mod_wren follows suit to keep line numbers reported in error messages synchronised with source code. For this to work, Wren opening tags should be followed by a newline, and closing tags placed on their own line:

<h1>Correct</h1><?wren
	System.write("These tags are opening and closing the Wren block correctly.")
?>
<p>That's how it's done!</p>

Classes and Modules

mod_wren supplies new classes for interacting with the server.

As with regular Wren, you can import other modules into your current document.

import "modules/something" will try to load modules/something.wren relative to the directory of your current document.