Program Synthesis with Large Language Models

Program synthesis is one of the grand challenges of artificial intelligence, but to date practical successes have focused on narrow settings and restricted domains. Large language models trained on massive corpora of web texts which include open-source code, programming websites, and tutorials have the potential to break through this barrier.This paper explores the limits of the current generation of large language models for program synthesis in general purpose programming languages. We evaluate the performance of the language model LaMDA PT [Freitas et al.,2021] on several program synthesis tasks, at a variety of scales ranging from 244M to 137B parameters. First, we introduce a new benchmark, Mostly Basic Programming Problems (MBPP), to measure the ability of these models to synthesize short Python programs from natural language descriptions. The benchmark consists of around 1000 crowd-sourced Python programming problems, designed to be solvable by entry level programmers, covering programming fundamentals, standard library functionality, and so on. Each problem consists of a task description, code solution and automated test-cases. We also introduce a Python version of the MathQA benchmark, which evaluates the ability of the models to synthesize code from more complex text. On both datasets, we evaluate synthesis performance and find that synthesis performance scales log-linearly with model size. In contrast to some previous work, we find that LaMDAPT achieves non-negligible preformance in a few-shot setting, although fine-tuning still performs much better. Thel argest models we consider can synthesize solutions to 58% of the problems from MBPP using few-shot learning with a well-designed prompt; across model sizes, fine-tuning on a held-out portion of the dataset improves performance by about 10 percentage points. Finally, we conduct a thorough error analysis, shedding light on where these models fall short as program synthesizers, what types of programs are most difficult to generate, and how the models might be improved. As part of that analysis, we explore the semantic grounding of these models, finding that even our largest models are generally unable to predict the output of a program given a specific input.

• Machine Intelligence