wesc (Python)

Python bindings for wesc's streaming HTML/web-component bundler. The Rust core runs in-process — no subprocess, no WASM — so you can build and server-render web components straight from a Python backend (Flask, FastAPI, Django, plain http.server, …).

pip install wesc

Prebuilt abi3 wheels ship for macOS, Linux, and Windows and work on CPython 3.8+. No Rust toolchain needed to install.

Usage

import wesc

# One-shot: returns a `BuildResult`. `result.html` is the full HTML output as
# `bytes`; `result.css` / `result.js` are the bundled assets as `str` (or
# `None`). Releases the GIL while it runs, so other threads keep working.
result = wesc.build(["./index.html"], minify=True)
html, css, js = result.html, result.css, result.js

# Streaming: low memory, chunk by chunk. The callback receives each `bytes`
# chunk, then `None` once to signal end-of-stream.
def on_chunk(chunk):
    if chunk is None:
        finish()
    else:
        write(chunk)

wesc.build_stream(["./index.html"], on_chunk)

Async servers

build releases the GIL, so the idiomatic way to await it from asyncio (FastAPI, etc.) is a worker thread:

import asyncio, wesc

result = await asyncio.to_thread(wesc.build, ["./index.html"], minify=True)

API

• build(input, *, outcss=None, outjs=None, minify=False) -> BuildResult
• build_stream(input, callback, *, outcss=None, outjs=None, minify=False) -> None

build returns a BuildResult with html: bytes, css: str | None, and js: str | None. build_stream streams HTML only (it still writes outcss/outjs to disk).

The bundler keeps a process-global file/template cache, so builds should not run concurrently within a single process — serialize them (the examples/python-server demo does exactly this).

Building from source

This is a maturin project. From this directory:

pip install maturin
maturin develop            # build + install into the active virtualenv
maturin build --release    # produce a wheel in target/wheels/

See the repo README's Python section for the broader project and crates/wesc-py/src/lib.rs for the binding source.