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Bibliographic Details
Main Authors: Princis, Henrijs, Sharma, Arindam, David, Cristina
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.22277
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author Princis, Henrijs
Sharma, Arindam
David, Cristina
author_facet Princis, Henrijs
Sharma, Arindam
David, Cristina
contents Large language models (LLMs) have shown remarkable ability to generate code, yet their outputs often violate syntactic or semantic constraints when guided only through natural language prompts. We introduce TreeCoder, the most general and flexible framework to date for exploring decoding strategies, constraints, and hyperparameters in LLMs, and use it in code generation to enforce correctness and structure during decoding rather than relying on prompt engineering. TreeCoder represents decoding as a tree search over candidate programs, where both decoding strategies and constraint functions - such as style, syntax, execution - are treated as first-class, optimisable components. This design enables systematic exploration and automatic tuning of decoding configurations using standard optimisation techniques. Experiments on the MBPP (Python) and SQL-Spider benchmarks show that TreeCoder consistently improves accuracy across open-source models such as CodeLlama, Mistral and DeepSeek, often outperforming their unconstrained baselines by considerable margins.
format Preprint
id arxiv_https___arxiv_org_abs_2511_22277
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle TreeCoder: Systematic Exploration and Optimisation of Decoding and Constraints for LLM Code Generation
Princis, Henrijs
Sharma, Arindam
David, Cristina
Machine Learning
Large language models (LLMs) have shown remarkable ability to generate code, yet their outputs often violate syntactic or semantic constraints when guided only through natural language prompts. We introduce TreeCoder, the most general and flexible framework to date for exploring decoding strategies, constraints, and hyperparameters in LLMs, and use it in code generation to enforce correctness and structure during decoding rather than relying on prompt engineering. TreeCoder represents decoding as a tree search over candidate programs, where both decoding strategies and constraint functions - such as style, syntax, execution - are treated as first-class, optimisable components. This design enables systematic exploration and automatic tuning of decoding configurations using standard optimisation techniques. Experiments on the MBPP (Python) and SQL-Spider benchmarks show that TreeCoder consistently improves accuracy across open-source models such as CodeLlama, Mistral and DeepSeek, often outperforming their unconstrained baselines by considerable margins.
title TreeCoder: Systematic Exploration and Optimisation of Decoding and Constraints for LLM Code Generation
topic Machine Learning
url https://arxiv.org/abs/2511.22277