fymo 0.18.1

Python SSR framework for Svelte 5 — esbuild pipeline, Node sidecar, SvelteKit-style remote functions

Fymo Framework

Production-ready Python SSR Framework for Svelte 5

Build modern web applications with Python backend and Svelte 5 frontend

Features

• Build-time esbuild pipeline — components compiled to hashed dist/client/*.js once, served as cacheable static assets.
• Cross-route shared chunks — packages imported by multiple pages (e.g. date-fns) are bundled once and shared.
• Persistent Node sidecar SSR — Python WSGI app talks to a long-lived Node process over stdio JSON; the sidecar imports prebuilt SSR modules and renders per request in microseconds.
• Minimal HTML response — typical page is < 10 KB; bundles loaded via <link rel="modulepreload"> + <script type="module" src=...>.
• fymo dev watcher — incremental rebuilds on save with SSE-driven browser reload.
• Any npm library — Node SSR has full Node API surface (fs, fetch, Buffer, streams).
• Svelte 5 runes — full $state, $derived, $effect, $props support.

Quick Start

Prerequisites

• Python 3.11+
• Node.js 20+ (Fymo's bundler shells out to esbuild)

Installation

pip install fymo

Create a New Project

fymo new my-app
cd my-app
npm install

Build and Serve

fymo dev             # incremental rebuild + browser auto-reload (development)

# or, for production:
fymo build           # produces dist/ with hashed JS/CSS bundles
fymo serve --prod    # gunicorn

Visit http://127.0.0.1:8000.

Project Structure

my-app/
├── app/
│   ├── controllers/     # Python controllers
│   ├── templates/       # Svelte components
│   ├── models/         # Data models
│   └── static/         # Static assets
├── dist/               # Built output (generated by fymo build)
├── config/             # Configuration
├── fymo.yml           # Project configuration
├── server.py          # Entry point
└── requirements.txt   # Python dependencies

Example Component

<!-- app/templates/home/index.svelte -->
<script>
  let { title, message } = $props();
  let count = $state(0);
  
  function increment() {
    count++;
  }
</script>

<div>
  <h1>{title}</h1>
  <p>{message}</p>
  <button onclick={increment}>
    Count: {count}
  </button>
</div>

# app/controllers/home.py
def getContext():
    return {
        'title': 'Welcome to Fymo',
        'message': 'Build amazing apps with Python and Svelte 5!'
    }

CLI Commands

• fymo new <project> — Create a new project
• fymo dev — Dev server with file watcher and live reload
• fymo serve — Alias for fymo dev; fymo serve --prod serves a built project via gunicorn
• fymo build — Build for production (produces dist/)
• fymo generate <type> <name> — Generate components/controllers

Configuration

Configure your project in fymo.yml:

name: my-app
version: 1.0.0

routes:
  root: home.index
  resources:
    - posts
    - users

server:
  host: 127.0.0.1
  port: 8000
  reload: true

Architecture

Fymo combines:

• Python for server-side logic and routing (WSGI)
• Svelte 5 for reactive UI components
• esbuild for fast, incremental JS/CSS bundling at build time
• Node.js sidecar for server-side rendering via stdio JSON protocol

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT License - see LICENSE file for details

Acknowledgments

• Built with Svelte 5
• Bundled with esbuild
• Inspired by modern web frameworks

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Built with love by the Fymo Team