transplang 0.1.0

Translate a strict subset of Python scripts into Rust programs.

Transplang

Translate a strict subset of Python scripts into compilable Rust programs.

---

Example

script.py

def total(nums):
    s = 0
    for n in nums:
        s += n
    return s

print(total([1, 2, 3, 4]))

Generated out.rs

fn total(nums: Vec<i32>) -> i32 {
    let mut s: i32 = 0;
    for n in nums {
        s = s + n;
    }
    s
}

fn main() {
    println!("{}", total(vec![1, 2, 3, 4]));
}

---

Supported Python constructs

Construct	Notes
def functions	scalar and Vec parameters
Integer literals	mapped to i32
String literals	mapped to &str
List literals	mapped to vec![…]
Variable assignment	let / let mut
Augmented assignment	+=, -=, *=, /=
Arithmetic	+, -, *, /
for x in y loops	iterating over lists or Vec params
return	last return rendered as tail expression
print()	mapped to println!

---

Unsupported (rejected with a clear error)

• import statements
• class definitions
• if / while / with / try
• async / await
• Decorators
• Comprehensions
• Dicts, sets
• Attribute access (obj.attr)
• Subscript access (x[i])

---

Architecture

Python file
    ↓
ast.parse()          [parser.py]
    ↓
SemanticModel        [analyzer.py]
    ↓
RustIR               [mapper.py]
    ↓
Rust source          [rust_generator.py]

No runtime dependencies; stdlib only (ast, argparse, pathlib).

Install

pip install transplang

Or from source:

git clone https://github.com/calchiwo/transplang.git
cd transplang
pip install -e .

---

Usage

transplang translate script.py --to rust

Write output to a file:

transplang translate script.py --to rust --output out.rs
rustc out.rs && ./out

---

Running tests

pip install pytest
pytest

Or without pytest:

python -m unittest discover -s tests

---

Scope

Transplang currently focuses on a very small subset of Python and Rust.

The goal of this version is simple: demonstrate that structured translation between programming languages can work in practice when the surface area is tightly controlled.

Only a limited set of constructs are supported:

• functions
• integers
• lists
• loops
• basic arithmetic
• print

Anything outside this scope is intentionally rejected.

This constraint keeps the system deterministic and makes it easier to reason about translation correctness.

Why I started small

Real software systems are complex. Languages differ in runtime models, type systems, and ecosystem conventions.

Attempting to translate entire applications immediately would produce unreliable results.

Instead, Transplang begins with a narrow slice of functionality to test the core idea: that a program can be analyzed structurally and rebuilt in another language.

If this approach proves reliable on small programs, the surface area can expand over time.

Long-term direction

Programs written in different languages ultimately describe the same underlying elements:

• state
• transformations
• control flow
• side effects

Transplang explores whether those elements can be extracted and reconstructed in another language environment.

The current prototype should be viewed as a minimal experiment around that idea.

Author

Caleb Wodi