Template engines are very important tools to craft Web applications and a few libraries exist to handle that tedious work.


For HTML5, Compose is quite appropriate.

app.get ("/", (req, res) => {
    return res.expand_utf8 (
        html ({},
            head ({},
                title ()),
            body ({},
                section (
                    h1 ({}, "Section Title")))));

It comes with two utilities: take and when to iterate and perform conditional evaluation.

var users = Users.all ();

take<User> (()     => { return users.next (); },
            (user) => { return user.username; });

when (User.current ().is_admin,
      () => { return p ({}, "admin") },
      () => { return p ({}, "user") });

Strings are not escaped by default due to the design of the library. Instead, all unsafe value must be escaped properly. For HTML, e is provided.

e (user.biography);

Templates and fragments can be store in Vala source files to separate concerns. In this case, arguments would be used to pass the environment.

using Compose.HTML5;

namespace Project.Templates
    public string page (string title, string content)
            div ({"id=%s".printf (title)},
                h2 ({}, e (title)),


Template-GLib provide a more traditional solution that integrates with GObject. It can render properties and perform method calls.

using Tmpl;

var home = new Template.from_resource ("home.tmpl");

app.get ("/", (req, res) => {
    var scope = new Scope ();
    scope.set_string ("title", "Home");
    home.expand (scope, res.body);