Pating

A general-purpose .paw templating engine. Pure Python, no npm, no Node, no build pipeline. Backend agnostic and usable standalone; Bao first for model-aware components and realtime.

Pating targets parity with Jinja2 (templating), Alpine (client reactivity), and HTMX (server interaction), unified under one .paw syntax. Use it to render web pages, HTML fragments, emails, reports, config files, or plain text.

This is a private, work-in-progress repository. It has no remote.

Install

pip install -e ".[dev]"

Only dependency for the core is markupsafe. The client runtime is a single prebuilt JS file (no build step).

Quick start

from pating import render

html = render("<h1>{title|upper}</h1>", {"title": "hello"})
# '<h1>HELLO</h1>'  (autoescaped by default)

Loops, conditionals, filters, whitespace control:

render(
    "<ul><for u in users><li>{u.name}<if u.admin> (admin)</if></li></for></ul>",
    {"users": [{"name": "Al", "admin": True}, {"name": "Bo", "admin": False}]},
)

Files, includes, and layout inheritance use an Environment with a loader:

from pating import render_file
render_file("templates/page.paw", {"title": "Users", "users": [...]})

The .paw syntax at a glance

{# a comment, dropped from output #}
{expr}                              {# interpolation, HTML-escaped by default #}
{value | filter(arg)}               {# filters, chainable #}
{a if cond else b}                  {# ternary #}

<if cond> ... <elif other> ... <else> ... </if>
<for item in items> ... <else> ... </for>      {# loop helpers: loop.index, .first, .last, .length, .cycle(...) #}
<set name = expr/>

<include "partial.paw">             {# include with current context #}
<include "partial.paw" with={'k': v}>

<extends "layout.paw">              {# layout inheritance #}
<block content> ... {super} ... </block>

<macro card(title, body="")> ... </macro>   {# reusable components #}
<call card("Hi")/>

{x -}   {- y}                       {# whitespace control: trim after / before #}

Client and server directives are plain HTML attributes that the small client runtime interprets in the browser:

<div p-data="{ count: 0 }">
  <button @click="count++">+</button>
  <span p-text="count"></span>
</div>

<button p-get="/items" p-target="#list" p-swap="beforeend">Load more</button>
<div p-sse="/events" p-swap="innerHTML"></div>

Documentation

• docs/USAGE.md: standalone rendering, use with FastAPI / Django / Flask, the client runtime, and the Bao-first extras.
• docs/SPEC.md: design and locked decisions.
• docs/BUILD_PLAN.md: the phased plan.
• Runnable examples/.

Status

• Phase 1 (templating core): production-ready. Full Jinja2-class feature set with a comprehensive test suite.
• Phase 2 (client reactivity) + Phase 3 (server interaction): the client runtime (src/pating/runtime/pating.js, ~17 KB unminified) and the Python directive builders are complete. The runtime has not yet been exercised by an automated browser test; the Python surface is tested.
• Phase 4 (Bao-first): complete behind an adapter interface and tested with a fake adapter. Bao is imported lazily and is never required by the core.
• Phase 5 (packaging/docs/examples): this README, docs/USAGE.md, and examples/.

See the report at the bottom of docs/USAGE.md for known gaps.