jstrukt / decaf2many

Java to Python transpiler

decaf2many: Java to Python Transpiler

Overview

Transpiles Java8 to the py2many dialect of python. Doing so preserves some information about types (char, int, long map to u16, i32, i64 respectively) and can be further transpiled to downstream languages supported by py2many, which include Kotlin and Rust among others.

This dialect can be thought of as a statically typed subset of python that's suitable as a universal intermediate language. It can also benefit from the rich set of tools and libraries that make up the python ecosystem.

If you're looking to use dynamic typing, this is probably not a good path for you.

Details

The tool is based on antlr4 and the "optimized" Java grammar

Usage

cat HelloWorld.java | decaf2many  # writes to stdout
decaf2many HelloWorld.java  # writes to HelloWorld.py
decaf2many --outdir /tmp HelloWorld.java  # writes /tmp/HelloWorld.py

To transpile to other languages

py2many --rust=1 HelloWorld.py
py2many --kotlin=1 HelloWorld.py

Sample programs

• HelloWorld: input output
• Expression: input output