Direct interface into Python

[MarcusRainbow]

The Rust generated by pypyrust is not directly useable from Python. For one thing, it uses native Rust types rather than variant types. For another, it uses Rust linkage conventions rather than C. However, it would be possible to auto-generate a thunk layer that exposed a Python-like interface on one side and a Rust-like interface on the other.

One possibility would be to generate Cython code that converted the Python into strongly-typed C-code. Then generate Rust code that converted this C-code into native Rust.