# What is genvm-lint and How to Use It for GenLayer Smart Contracts

> Discover genvm-lint, a fast static analysis tool for GenLayer smart contracts. Learn how to use it to catch deployment-blocking errors quickly and efficiently.

- Repository: [GenLayer Labs/genlayer-project-boilerplate](https://github.com/genlayerlabs/genlayer-project-boilerplate)
- Tags: how-to-guide
- Published: 2026-08-20

---

**genvm-lint is a static analysis tool that validates GenLayer intelligent contracts for deployment-blocking errors in approximately 250 milliseconds per file.**

genvm-lint ships as the `genvm-linter` package in the `genlayerlabs/genlayer-project-boilerplate` repository. It performs pre-deployment validation to catch forbidden imports, incorrect storage types, and missing decorators before contracts reach the GenLayer Studio environment.

## What is genvm-lint?

genvm-lint is the command-line interface bundled inside the **genvm-linter** Python package. It statically analyzes intelligent contracts written for the GenLayer Virtual Machine (GenVM) to enforce deterministic execution rules. According to the source code in `genlayer-project-boilerplate`, the tool completes validation in roughly **250 ms per contract**, making it suitable for rapid iteration during development.

The linter validates compliance with GenLayer's unique execution model, where contracts must avoid non-deterministic operations unless properly isolated. This catches errors that would otherwise block deployment to the GenLayer Studio environment.

## Installation and Setup

The `genvm-linter` package is listed as a dependency in the project's [`requirements.txt`](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/requirements.txt) at [line 3](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/requirements.txt#L3). Install it alongside other development dependencies:

```bash
pip install -r requirements.txt

```

This installs the `genvm-lint` CLI globally within your Python environment, making it available for local validation and CI/CD pipelines.

## Linting Rules and Validation Checks

The validation rules enforced by genvm-lint are documented in the repository's [`README.md`](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/README.md) ([lines 62-67](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/README.md#L62-L67)). The tool performs four critical categories of checks:

- **Forbidden imports**: Blocks imports of `os`, `sys`, `subprocess`, and other modules that could introduce non-deterministic behavior or security vulnerabilities.
- **Correct storage types**: Enforces use of GenLayer-specific containers like `TreeMap`, `DynArray`, and `u256` instead of native Python lists, dictionaries, or integers.
- **Required decorators**: Validates that contract methods use `@gl.public.view` or `@gl.public.write` decorators and include proper return-type annotations.
- **Equivalence-principle compliance**: Ensures non-deterministic operations are wrapped in equivalence-principle blocks to guarantee consistent execution across validator nodes.

## How to Run genvm-lint Locally

Validate individual contracts or entire directories using the `genvm-lint check` command. The basic syntax follows the pattern documented in [`README.md`](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/README.md) ([lines 54-60](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/README.md#L54-L60)):

**Check a single contract:**

```bash
genvm-lint check contracts/football_bets.py

```

**Check all contracts in a directory:**

```bash
genvm-lint check contracts/*.py

```

The tool outputs specific line-by-line diagnostics for any violations, allowing developers to fix storage type mismatches or missing decorators before running tests.

## CI/CD Integration with GitHub Actions

The repository includes an automated workflow in [`.github/workflows/ci.yml`](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/.github/workflows/ci.yml) ([lines 14-20](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/.github/workflows/ci.yml#L14-L20)) that executes genvm-lint on every push and pull request. The configuration installs dependencies from [`requirements.txt`](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/requirements.txt) then runs the linter against the sample contract:

```yaml
jobs:
  lint-contracts:
    name: Lint Contracts
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"
      - run: pip install -r requirements.txt
      - run: genvm-lint check contracts/football_bets.py

```

This ensures that no contract violating GenVM rules merges into the main branch.

## Typical Development Workflow

The boilerplate project structures development around genvm-lint as a gate between editing and testing:

1. **Edit contract code** in [`contracts/my_contract.py`](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/contracts/my_contract.py).
2. **Validate with genvm-lint** using `genvm-lint check contracts/my_contract.py` and fix reported issues.
3. **Run direct-mode tests** with `pytest tests/direct/ -v` for fast, in-memory validation (milliseconds per test).
4. **Execute integration tests** using `gltest tests/integration/ -v -s` against GenLayer Studio once linting passes.

Because genvm-lint validates contracts statically, it catches deployment-blocking issues early, allowing developers to rely on the fast direct-mode tests before committing to slower full-stack integration testing.

## Summary

- genvm-lint is a **~250 ms static analysis tool** bundled in the `genvm-linter` package.
- It enforces **four rule categories**: forbidden imports, storage types, decorators, and equivalence-principle compliance.
- Install via [`requirements.txt`](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/requirements.txt) ([line 3](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/requirements.txt#L3)) and run with `genvm-lint check <file>`.
- The tool integrates automatically into CI via [`.github/workflows/ci.yml`](https://github.com/genlayerlabs/genlayer-project-boilerplate/blob/main/.github/workflows/ci.yml).
- It serves as the first validation gate in the development workflow before direct-mode and integration testing.

## Frequently Asked Questions

### What does genvm-lint check for?

genvm-lint validates four specific categories of GenLayer contract requirements: forbidden system imports (like `os` and `sys`), correct usage of storage types (`TreeMap`, `DynArray`, `u256`), mandatory method decorators (`@gl.public.view`, `@gl.public.write`), and equivalence-principle compliance for non-deterministic operations.

### How fast is genvm-lint?

The tool executes in approximately **250 milliseconds per contract**, making it significantly faster than full integration tests. This speed allows developers to run the linter continuously during development without interrupting workflow.

### Can I run genvm-lint on multiple contracts at once?

Yes. While you can validate single files with `genvm-lint check contracts/football_bets.py`, the CLI accepts glob patterns like `genvm-lint check contracts/*.py` to validate entire directories in a single command.

### Is genvm-lint required before deploying to GenLayer Studio?

While the linter itself is a development tool, the rules it enforces are mandatory for successful deployment. Contracts that fail genvm-lint validation contain errors that GenLayer Studio will reject, making the linter an essential pre-deployment step in the development workflow.