wasmpy

WebAssembly in Python.

Wasmpy is a lightweight layer that sits between Python and WebAssembly. When attempting to import a WebAssembly file, the file is converted into machine code for native speeds.

Installing

python3 -m pip install wasmpy

Usage

To get started, first import the wasmpy module to register the WebAssembly import hooks.

Then you can just import wasm_or_wat_file to load a WebAssembly module.

Usage with Python modules

|-  my_module
    |-  __init__.py
    |-  wasm_math.wat

# __init__.py

import wasmpy
from .wasm_math import add

;; wasm_math.wat

(module
    (func (export "add") (param i32 i32) (result i32)
        (i32.add (local.get 0) (local.get 1))
    )
)

>>> import my_module
>>> my_module.add(45, 960)
1005
>>>

Invalid function names

Functions exported from WebAssembly can also be accessed from the module by using their name as a key.

For exported names that aren't valid Python identifiers or which start with a _, this is the only valid way of accessing these functions.

;; wasm_math.wat

(module
    (func (export "add one") (param i32) (result i32)
        (i32.add (local.get 0) (i32.const 1))
    )
)

>>> import wasmpy
>>> import wasm_math
>>> wasm_math["add one"](11)
12
>>>

Building From Source

On Windows this requires mingw-w64

git clone https://github.com/olivi-r/wasmpy.git
cd wasmpy
make -f <linux/windows>.mk
python3 -m pip install .

Limitations

Wasmpy is still in active development, and only supports x86/x86-64 Windows and Linux machines and lacks some key features:

• most memory instructions
• most control instructions
• imports
• tables

Goals

• Current target:

  • Reach compatability with the MVP

• Future Goals

  • Native support for more architectures, particularly those supported by manylinux
  • Interfacing with the Python C API from WebAssembly (in conjunction with the Wasmpy sister project wasmpy-build) to allow compiled extension modules that are platform independent
  • Compatibility with Pyodide
  • Python implementation support for Jython, PyPy etc.
  • Support for WebAssembly proposals
  • Support for WASI snapshots, as well as support for supersets such as WASIX