metaborg-chocopy's Introduction

metaborg-chocopy

This repository contains an implementation of the ChocoPy programming language, with additional support for Python 3.6+-style exceptions. The implementation is written using version 3 of the Spoofax language workbench. Part of this project was written as part as a case-study for Dynamix: A Domain-Specific Language for Dynamic Semantics.

You can import this repository in your Spoofax 3 eclipse instance by following the steps here.

Exception Extensions

This version of ChocoPy has additional support for exceptions. In particular, the following constructs have been added:

raise exp

try:
    body
except ClassName as ident:
    body
finally:
    body

The behavior of exceptions largely mimics that of exceptions in Python, with a few key differences:

Raised exceptions can be any object of any class, and do not need to inherit Exception (there's no Exception in ChocoPy).
Caught exceptions bound in except blocks must be declared beforehand, similar to the loop variable for for blocks.
Classes declared in an except block must match exactly. If Bar is a subclass of Foo, an except Foo as ex: block will ONLY catch Foo instances, not Bar instances.

This language project contains the following parts:

chocopy/src/syntax: The SDF3 grammar definition for ChocoPy, with extensions for exceptions.
chocopy/src/statics: The Statix specification for ChocoPy, with extensions for exceptions and tagging for boxing operations.
chocopy/src/dynamics: The Dynamix specification for ChocoPy, with extensions for exceptions and support for automatic boxing.

Acknowledgements

The original SDF3 grammar and Statix specification for ChocoPy was written by Alexander Sterk and Tim Nederveen. Adjustments to add support for exceptions, as well as the Dynamix specification, are courtesy of Thijs Molendijk.

License

The files in this repository are licensed under the Apache License, Version 2.0. You may use the files in this repository in compliance with the license.

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