Louis Mandel

My research focuses on the design and implementation of programming languages, compilers, and developer tools. Throughout my work, I have been particularly interested in building abstractions that make complex computational models more expressive, reliable, and programmable. The themes below highlight the main threads of this work with some selected publications.

LLM-based Applications

I work on programming abstractions for large language model (LLM) applications. This includes the design and implementation of PDL. PDL has been used, for example, to build software engineering and compliance agents. I also contributed to training the model for Ansible Lightspeed, a code assistant for Ansible.

• PPDL: LLM-Based Flows as Probabilistic Programs
  L. Mandel, G. Baudart, M. Vaziri, M. Hirzel. ICML 2026
• AutoPDL: Automatic Prompt Optimization for LLM Agents
  C. Spiess, M. Vaziri, L. Mandel, M. Hirzel. AutoML 2025
• Cross-lingual Transfer in Programming Languages: An Extensive Empirical Study
  R. Baltaji, S. Pujar, M. Hirzel, L. Mandel, L. Buratti, L. R. Varshney. TMLR 2025
• PDL: A Declarative Prompt Programming Language
  M. Vaziri, L. Mandel, C. Spiess, M. Hirzel. arXiv 2024
• Ansible Lightspeed: A Code Generation Service for IT Automation
  P. Sahoo, S. Pujar, G. Nalawade, R. Genhardt, L. Mandel, L. Buratti. ASE 2024
• Generating Chat Bots from Web API Specifications
  M. Vaziri, L. Mandel, A. Shinnar, J. Siméon, M. Hirzel. Onward! 2017

Probabilistic Programming

A second major theme of my work is probabilistic programming: the design of languages and compilation techniques that make statistical models easier to write, execute, and reason about.

• Schedule Agnostic Semantics for Reactive Probabilistic Programming
  G. Baudart, L. Mandel, C. Tasson. ACM TOPML 2025
• Inference Plans for Hybrid Particle Filtering
  E. Y. Cheng, E. Atkinson, G. Baudart, L. Mandel, M. Carbin. POPL 2025
• Semi-Symbolic Inference for Efficient Streaming Probabilistic Programming
  E. Atkinson, C. Yuan, G. Baudart, L. Mandel, M. Carbin. OOPSLA 2022
• Statically Bounded-Memory Delayed Sampling for Probabilistic Streams
  E. Atkinson, G. Baudart, L. Mandel, C. Yuan, M. Carbin. OOPSLA 2021
• Compiling Stan to Generative Probabilistic Languages and Extension to Deep Probabilistic Programming
  G. Baudart, J. Burroni, M. Hirzel, L. Mandel, A. Shinnar. PLDI 2021
• Reactive Probabilistic Programming
  G. Baudart, L. Mandel, E. Atkinson, B. Sherman, M. Pouzet, M. Carbin. PLDI 2020

Data-centric Languages

I contributed to developing Q*cert, a framework, implemented in Rocq, for building and verifying compilers for data-centric languages like SQL. I also worked on static analysis for GraphQL to prevent denial of service attacks.

• Translating Canonical SQL to Imperative Code in Coq
  V. Benzaken, E. Contejean, M. H. Hachmaoui, C. Keller, L. Mandel, A. Shinnar, J. Siméon. OOPSLA 2022
• A Principled Approach to GraphQL Query Cost Analysis
  A. Cha, E. Wittern, G. Baudart, J.C. Davis, L. Mandel, J. Laredo. ESEC/FSE 2020
  ACM SIGSOFT Distinguished Paper award
• Prototyping a Query Compiler using Coq (experience report)
  J. Auerbach, M. Hirzel, L. Mandel, A. Shinnar, J. Siméon. ICFP 2017
• Handling Environments in a Nested Relational Algebra with Combinators and an Implementation in a Verified Query Compiler
  J. Auerbach, M. Hirzel, L. Mandel, A. Shinnar, J. Siméon. SIGMOD 2017

Reactive and Synchronous Programming Languages

A long-standing theme of my work is designing reactive and synchronous languages for systems that interact continuously with their environment. This includes both foundational language design and practical implementations. Among others, I have worked on projects including ReactiveML, JoCaml, Lucy-n, X10, and CloudLens.

• Time Refinement in a Functional Synchronous Language
  L. Mandel, C. Pasteur, M. Pouzet. SCP 2015
• Reactivity of Cooperative Systems
  L. Mandel, C. Pasteur, M. Pouzet. SAS 2014
• A Synchronous Embedding of Antescofo, a Domain-Specific Language for Interactive Mixed Music
  G. Baudart, F. Jacquemard, L. Mandel, M. Pouzet. EMSOFT 2013
• Static scheduling of Latency Insensitive Designs with Lucy-n
  L. Mandel, F. Plateau, M. Pouzet. FMCAD 2011
• Lucy-n: a n-Synchronous Extension of Lustre
  L. Mandel, F. Plateau, M. Pouzet. MPC 2010
• Programming in JoCaml
  L. Mandel, L. Maranget. ESOP 2008, tool demonstration
• Simulation and Verification of Asynchronous Systems by means of a Synchronous Model
  N. Halbwachs, L. Mandel. ACSD 2006
• ReactiveML: a reactive extension to ML
  L. Mandel, M. Pouzet. PPDP 2005
  PPDP 2005 Test-of-Time Award