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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
Times are displayed in time zone: Eastern Time (US & Canada) change

10:00 - 10:45: Safety & CorrectnessCC Research Papers at CC Virtual Room
Chair(s): Jan VitekNortheastern University / Czech Technical University
10:00 - 10:15
Talk
A Modern Compiler for the French Tax CodeArtifacts Evaluated – Reusable v1.1Results Reproduced v1.1Artifacts Available v1.1
CC Research Papers
Denis MerigouxInria, Raphaël MonatSorbonne University; CNRS; LIP6, Jonathan ProtzenkoMicrosoft Research
10:15 - 10:30
Talk
NSan: A Floating-Point Numerical Sanitizer
CC Research Papers
Clement CourbetGoogle Research
10:30 - 10:45
Talk
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 MiuImperial College London; Bloomberg, Francisco FerreiraImperial College London, Nobuko YoshidaImperial College London, Fangyi ZhouImperial College London
Pre-print Media Attached