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CC 2021
Tue 2 - Wed 3 March 2021 Online Conference
Wed 3 Mar 2021 10:00 - 10:15 at CC Virtual Room - Safety & Correctness Chair(s): Jan Vitek

In France, income tax is computed from taxpayers' individual returns, using an algorithm that is authored, designed and maintained by the French Public Finances Directorate (DGFiP). This algorithm relies on a legacy custom language and compiler originally designed in 1990, which unlike French wine, did not age well with time. Owing to the shortcomings of the input language and the technical limitations of the compiler, the algorithm is proving harder and harder to maintain, relying on ad-hoc behaviors and workarounds to implement the most recent changes in tax law. Competence loss and aging code also mean that the system does not benefit from any modern compiler techniques that would increase confidence in the implementation.

We overhaul this infrastructure and present Mlang, an open-source compiler toolchain whose goal is to replace the existing infrastructure. Mlang is based on a reverse-engineered formalization of the DGFiP's system, and has been thoroughly validated against the private DGFiP test suite. As such, Mlang has a formal semantics; eliminates previous hand-written workarounds in C; compiles to modern languages (Python); and enables a variety of instrumentations, providing deep insights about the essence of French income tax computation. The DGFiP is now officially transitioning to Mlang for their production system.

Wed 3 Mar

Displayed time zone: Eastern Time (US & Canada) change

10:00 - 10:45
Safety & CorrectnessCC Research Papers at CC Virtual Room
Chair(s): Jan Vitek Northeastern University / Czech Technical University
A Modern Compiler for the French Tax CodeArtifacts Evaluated – Reusable v1.1Results Reproduced v1.1Artifacts Available v1.1
CC Research Papers
Denis Merigoux Inria, Raphaël Monat Sorbonne University; CNRS; LIP6, Jonathan Protzenko Microsoft Research
NSan: A Floating-Point Numerical Sanitizer
CC Research Papers
Clement Courbet Google Research
Communication-Safe Web Programming in TypeScript with Routed Multiparty Session TypesArtifacts Evaluated – Reusable v1.1Results Reproduced v1.1Artifacts Available v1.1
CC Research Papers
Anson Miu Imperial College London; Bloomberg, Francisco Ferreira Imperial College London, Nobuko Yoshida Imperial College London, Fangyi Zhou Imperial College London
Pre-print Media Attached