feat: add contributing guidelines

CONTRIBUTING

@@ -0,0 +1,102 @@
+# Contributing to `nada-numpy`
+
+Thank you for considering contributing to `nada-numpy`! There are two ways to contribute to `nada-numpy`:
+
+1. [Open issues](#open-issues) to report bugs and typos, or to suggest new ideas.
+2. [Submit a PR](#submit-a-pull-request) with a new feature or improvement.
+
+To ensure a consistent development process, please follow the guidelines outlined below.
+
+## Code quality and type checking
+
+- All contributions must adhere to the project's coding standards. We enforce these standards using `pylint` for code quality and `mypy` for type checking. 
+- Before submitting your contributions, ensure that your code passes both `pylint` and `mypy` checks.
+- These tools are also integrated into our CI/CD pipeline, and any PR will be automatically validated against these checks.
+
+## Development 
+
+We recommend continuously running your code through `pylint` and `mypy` during the development process. These tools help identify potential issues early, enforce coding standards, and maintain type safety.
+
+### Installation
+
+1. Install [black](https://pypi.org/project/black/) and [isort](https://pycqa.github.io/isort/) for code formating
+```bash
+pip3 install black && isort
+```
+2. Fork the [repo](https://github.com/NillionNetwork/nada-numpy.git)
+3. Install from source the `nada-numpy` library:
+```bash
+cd nada-numpy
+pip3 install -e .
+```
+
+### Adding tests
+
+The [`tests/nada-tests`](https://github.com/NillionNetwork/nada-numpy/tree/main/tests/nada-tests) folder contains the testing infrastructure for `nada_numpy`. You will need to create one or more scripts to test your functionality. You can read the [docs](https://docs.nillion.com/nada#generate-a-test-file) for more info about testing. Follow these steps for testing:
+
+1. Add a script to [`tests/nada-tests/nada-project.toml`](https://github.com/NillionNetwork/nada-numpy/blob/main/tests/nada-tests/nada-project.toml).
+
+2. Place your test script in [`tests/nada-tests/src/`](https://github.com/NillionNetwork/nada-numpy/blob/main/tests/nada-tests/src), where it will verify the expected behavior.
+
+3. Generate the test file by running 
+```bash
+nada generate-test --test-name <TEST_NAME> <PROGRAM>
+```
+and placing it in [`tests/nada-tests/tests/`](https://github.com/NillionNetwork/nada-numpy/blob/main/tests/nada-tests/tests).
+
+4. Finally, add the script to the `TESTS` array in [`tests/test_all.py`](https://github.com/NillionNetwork/nada-numpy/blob/dd112a09835c2354cbf7ecc89ad2714ca7171b20/tests/test_all.py#L6) to integrate it with the CI/CD pipeline.
+
+## Submit a Pull Request
+
+We actively welcome your pull requests. Please follow these steps to successfully submit a PR:
+
+1. Fork the [repo](https://github.com/NillionNetwork/nada-numpy.git) and create your branch from `main`.
+2. If you've added code that should be tested, add tests as explained [above](#adding-tests). 
+3. Ensure that the test suite passes. Under [`tests/nada-tests/tests/`](https://github.com/NillionNetwork/nada-numpy/blob/main/tests/nada-tests/tests) run 
+```bash
+nada test <TEST_NAME>
+```
+4. Run from the root directory both 
+```bash
+black . && isort .
+```
+5. Ensure that your code passes both `pylint` and `mypy` checks:
+```bash
+poetry run pylint
+poetry run mypy
+```
+
+## Hints to add new features
+
+Below we provide some hints on how to add new features. We give two examples: adding a `NadaArray` method and adding a `Rational` method.
+
+### New `NadaArray` method
+
+As an example, we use the `variance` operation to describe the development flow:
+
+1. **Integrate the variance function:**
+   - In [`nada_numpy/array.py`](https://github.com/NillionNetwork/nada-numpy/blob/main/nada_numpy/array.py), integrate the `variance` method inside the `NadaArray` class as a new member function. This will allow the `variance` to be called as `array.var()`.
+
+2. **Add a Wrapper in `nada_numpy/funcs.py`:**
+   - In `nada-numpy`, functions can also be called in the form `na.var(array)`. To support this, add a wrapper in [`nada_numpy/funcs.py`](https://github.com/NillionNetwork/nada-numpy/blob/main/nada_numpy/funcs.py). You can refer to the existing functions in this file to see how they simply wrap around `array.var()` in this context.
+
+### New `Rational` method
+
+As an example, we use the exponential `exp` function to describe the development flow:
+
+1. **Integrate the exp function with Rational:**
+   - In [`nada_numpy/types.py`](https://github.com/NillionNetwork/nada-numpy/blob/main/nada_numpy/types.py), integrate the `exp` method inside both the `Rational` and `SecretRational` classes as a new member function. This will allow the `exp` to be called as `value.exp()`.
+
+2. **Integrate the exp function with NadaArray:**
+   - In [`nada_numpy/array.py`](https://github.com/NillionNetwork/nada-numpy/blob/main/nada_numpy/array.py), integrate the `exp` method inside the `NadaArray` class as a new member function. This will allow the `exp` to be called as `array.exp()`.
+
+3. **Add a Wrapper in `nada_numpy/funcs.py`:**
+   - In `nada-numpy`, functions can also be called in the form `na.exp(array)`. To support this, add a wrapper in [`nada_numpy/funcs.py`](https://github.com/NillionNetwork/nada-numpy/blob/main/nada_numpy/funcs.py). You can refer to the existing functions in this file to see how they simply wrap around `array.exp()` in this context.
+
+
+## Open Issues
+
+We use [GitHub issues](https://github.com/NillionNetwork/nada-numpy/issues/new/choose) to report bugs and typos, or to suggest new ideas. Please ensure your description is clear and has sufficient instructions to be able to reproduce the issue.
+
+## License
+By contributing to `nada-numpy`, you agree that your contributions will be licensed under the [LICENSE](./LICENSE) file in the root directory of this source tree.

README.md

@@ -37,6 +37,12 @@ poetry install
 poetry run pytest
 ```
 
+## Join Nillion community and contribute
+
+Please join the Nillion community on [Discord](https://discord.com/invite/nillionnetwork).
+
+See the [CONTRIBUTING](./CONTRIBUTING) file for how to contribute to `nada-numpy`.
+
 ## License
 
 This project is licensed under the Apache2 License. See the LICENSE file for details.