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LEVER: Learning to Verify Language-to-Code Generation with Execution

Code for paper "LEVER: Learning to Verify Language-to-Code Generation with Execution". LEVER is a simple method that improves the code generation ability of large language models trained on code (CodeLMs), by learning to verify and rerank CodeLM-generated programs with their execution results. LEVER + Codex (code-davinci-002) achieves new SOTA results on the Spider, WikiTableQuestions, GSM8k, and MBPP datasets.

Updates

• 2023-07-05: Check out our online demo on Huggingface Space!
• 2023-07-04: (Trained) Model weights for Codex on all 4 datasets are available on Huggingface, check the Model Checkpoints section!
• 2023-07-03: Initial code release
• 2023-04-24: LEVER is accepted to ICML'23!

Setup

Installation

(Recommended) Create a new conda environment

conda create -n lever python=3.8
conda activate lever

Install the dependencies

pip install -r requirements.txt

NOTE: all of the pipelines are only tested on Linux machines, you may need to build your own tree-sitter parsers if a different platform is used.

Data

We share only the verification data, which is essential to reproduce our results, under the CC-BY-NC 4.0 license. For the original datasets, please refer to their own pages.

Download the data from here and create a data folder:

cd lever
mkdir data
cd data
unzip lever_verification_data.zip

After this, make sure your data directory looks something like this:

data
|-- gsm8k
|   |-- ...
|-- mbpp
|   |-- ...
|-- spider 
|   |-- ...
|-- wikitq
|   |-- wikitq_codex_verification_dev.jsonl
|   |-- wikitq_codex_verification_test.jsonl
|   |-- wikitq_codex_verification_train.jsonl

Optional Setups

(For Codex) Set up OpenAI API key. Either put this line in your ~/.bashrc (or equivalent), or add this line to every inference commands:

export OPENAI_API_KEY=<your key, should start with "sk-">

(For experiment logging) Prepend export EXP_NAME=<your exp name> to the python commands to log to wandb, for example:

export EXP_NAME=lever-reproduce-mbpp; 

But you may need to setup a W&B account first (you may follow the instructions here). Then change the following lines in trainer.logger+ fields of the yaml config file you would like to run:

entity: <your-user/org-name>
project: <your-project-name>

(Common error) At any point, if you met with the Python import problem (e.g., ModuleNotFoundError), try doing this in the main (lever) directory:

export PYTHONPATH=`pwd`

Usage

If you would like to:

• Try out LEVER or look at some more examples, we highly recommend you to visit our Demo Page;
• Reproduce our results on all datasets on preprocessed datasets, first check the Data section to download the data, then see the Reproduce section;
• Apply trained LEVER on one of the four datasets, but to the outputs of different code LLM (e.g., GPT-4, ChatGPT, StarCoder), follow the instructions at New LLMs section;
• Apply LEVER to a different dataset, this requires generating training data and re-train LEVER from scratch, please follow the instructions at Training section.

Model Checkpoints

For easy reproducibility, we share the weights of all the trained models for all 4 datasets on the huggingface model hub:

• LEVER for Codex on Spider: niansong1996/lever-spider-codex
• LEVER for Codex on WikiTQ: niansong1996/lever-wikitq-codex
• LEVER for Codex on GSM8K: niansong1996/lever-gsm8k-codex
• LEVER for Codex on MBPP: niansong1996/lever-mbpp-codex

If you would like to use the trained model weights for InCoder and CodeGen models, please open a feature request here.

Inference

If you would like to apply trained LEVER models to existing datasets, to existing models, or maybe even outputs of different code LLMs*, you only need to load the pretrained weights of LEVER and run inference.

*: As shown in Table 8 of the paper, transfer learning works surprisingly well.

Reproduce

The easiest way to reproduce our results is to run the trained models on the prepared datasets used in the paper. After obtaining the data and put them in the specific locations as described in the Data section, run the following commands with <dataset>=spider|wikitq|gsm8k|mbpp

python finetuning/trainer.py validate --config finetuning/training_configs/verification/<dataset>_verification.yaml --trainer.accelerator gpu --trainer.gpus 1

For example, it only takes ~7mins to run LEVER on Spider dev set on the CPUs* of my M1 Max MacBook Pro, with the following command:

python finetuning/trainer.py validate --config finetuning/training_configs/verification/spider_verification.yaml --trainer.accelerator cpu --trainer.gpus 4 --data.val_batch_size 4

Of course, also feel free to modify the yaml config file directly, all the fields should be self-explanatory.

*: I can't get MPS to work with T5 models, if you know how to do it, please open an issue / PR.

New LLMs

To apply LEVER to new LLMs on existing datasets, for each example, you first need to sample candidate programs with the new LLMs. We have some example yaml on how you can do this for GSM8K for Codex, InCoder and CodeGen models in finetuning/training_configs/few_shot/.

To add a new LLM in the few-shot generation pipeline, you would need to add it in finetuning/lightning_modules/models/seq2seq_model_util.py

    ...
    elif model_name.startswith("codex-"):
        ...
    elif model_name == ###### Add your model here ##########
        """Initialize and return the tokenizer and the model """
        ######## End adding model ##############
    else:
        print(f"unknown model: {model_name}")
        raise NotImplementedError

Also don't forget to update the two helper functions accordingly:

def is_model_gpt_style(name: str) -> bool:
    ...

def is_encoder_only_model(name: str) -> bool:
    ...

After all this is done, you should be able to run few-shot generation with your own model like this:

python finetuning/trainer.py validate --config finetuning/training_configs/few_shot/<your_new_llm_config>.yaml

Training

While LEVER works well when it's trained with the outputs from another LLM and apply it to a different LLM for the same dataset, if you would like to apply LEVER to a different dataset, you may need to implement a new dataset under our framework, generate your own training data and train your own LEVER model.

While it will be too verbose to give a full tutorial of all these parts, we point you to the different parts of the repo and hopefully you can follow those examples to build such a pipeline for a new dataset.

Implement new dataset class for few-shot generation

First check out the examples at finetuning/lightning_modules/datasets, more specifically, we suggest look at these two classes FewShotMathQADataset and FewShotMathQADataModule in finetuning/lightning_modules/datasets/mathqa_reader.py and the functions you need to override.

Running few-shot generation

You would need to run few-shot generation on both the training data and dev/test data for your own dataset, the general command should be like:

python finetuning/trainer.py validate --config finetuning/training_configs/few_shot/<your_new_dataset_config>.yaml

Implement new dataset class for verification

Now that you have the candidate programs for your own dataset, you need to implement another two dataset classes for verification, for this, check out MathQAEndVerificationDataset and MathQAEndVerificationDataModule in finetuning/lightning_modules/datasets/mathqa_reader.py for examples.

Train LEVER

Next, you will train LEVER with the training data you just generated, with command like:

python finetuning/trainer.py fit --config finetuning/training_configs/verification/<your_new_dataset_config>.yaml

Run LEVER on your dev/test data

By default, if you put the path of the dev data in the yaml file of <your_new_dataset_config>.yaml in your previous command, you should see the validation results between each epochs of training, but you can also just run it like:

python finetuning/trainer.py validate --config finetuning/training_configs/verification/<your_new_dataset_config>.yaml --model.load_ckpt_file <path_to_ckpt>

References

Part of the code adapted from https://github.com/Yale-LILY/NLP4Code (Apache-2.0 License) and https://github.com/microsoft/TraceCodegen (MIT License).

If you use the code or data in this repository, please cite:

@inproceedings{ni2023lever,
  title={Lever: Learning to verify language-to-code generation with execution},
  author={Ni, Ansong and Iyer, Srini and Radev, Dragomir and Stoyanov, Ves and Yih, Wen-tau and Wang, Sida I and Lin, Xi Victoria},
  booktitle={Proceedings of the 40th International Conference on Machine Learning (ICML'23)},
  year={2023}
}