Tela — views and the browser seam

Tela is Faber's view library: typed HTML and SVG view values, a serializer that turns them into markup, and the DOM and Canvas2D contracts that let a Faber program talk to a browser. It is imported as tela:*. The name is the Latin for web, fabric.

The idea is that a view is data, not a string. You build a tree of typed values, Tela checks the tree, and only a valid tree becomes markup. Nothing is concatenated by hand, so the usual ways of producing broken or unsafe HTML are not available on the ordinary path.

The current package version is 0.0.0. Read the status section before planning work on it — it is early, and the protocol and the static renderer are the part that works today.

A first view#

Build a value, serialize it. The text contains a bare &; Tela escapes it.

import from "tela:tela" tela

main {
    const tela.View greeting ← tela.element_view(tela.html_space(), "p", [tela.text_view("Fish & chips")])
    print tela.html_view(greeting) coalesce "invalid"
}

This prints <p>Fish &amp; chips</p>. html_view returns text or null: if any check on the tree fails, it returns null and emits nothing — never partial markup.

Design#

• A typed tree. A View is one of three things: an element (tag, space, attributes, properties, children), a text node, or a fragment. There is no raw-markup variant in the ordinary path, so there is no way to smuggle unescaped markup in as a value.
• One escape path. Text and attribute values go through the same escape function. The set of escaped characters differs between text and attributes, but no serializer path concatenates an unescaped value.
• Fail closed. Before any markup is emitted the serializer checks the whole tree: tag and attribute names, the HTML or SVG namespace, and void-element structure. A failed check means no output at all.
• Identity is explicit. An element may carry a typed Identity, which the serializer writes as a data-tela attribute through the same escape path. Identity is never derived from position.
• Deterministic by design. The serializer is written so that the same tree gives the same bytes.

Modules#

Each tela:<stem> import resolves to src/<stem>.fab. As with the other libraries, import the leaf that owns what you use.

The kernel depends on nothing else: no Norma, no Triga, no generated runtime.

Targets#

Tela's manifest lists two targets, rust and ts, and the DOM and Canvas2D modules bind to a TypeScript host runtime through a bindings file. The TypeScript route is the one the library was built around; the Rust route is listed but does not build yet.

Status#

As of 2026-09-30:

Use Tela to see how a typed view protocol looks in Faber, and to build static markup with checked output. Do not plan on it as a finished UI framework.

Source: github.com/faberlang/tela.