henri is an experimental domain-specific programming language for real-time sound synthesis, developed in the context of artistic research at the Institute of Electronic Music and Acoustics in Graz. It originates from a question about how computer-music languages shape what can be thought and made. Most existing audio languages organise sound around signal-flow graphs, unit generators, or sample buffers — abstractions inherited from analogue circuit design and from functional programming, each carrying a specific aesthetic that constrains what kinds of sonic ideas come naturally. henri proposes a different commitment: every entity in the language is a system of ordinary differential equations, integrated at audio rate. Oscillators, filters, networks of adaptive coupled oscillators, feedback instruments — all are written as the equations they are, with no translation into a separate "synthesis" vocabulary. The language is named after Henri Poincaré, whose geometrical analysis of dynamical systems is its conceptual foundation. It is in continuous use in the author's compositional and performance work, including feedback performances and the ensemble project Altraconsonanza. The commitment is sustained technically by a symmetric symplectic splitting integrator with oversampling for stability, an implicit midpoint scheme with Newton–Raphson iteration for stiff systems such as resonant virtual-analog filters, and JIT compilation via LLVM ORC v3 to native code at sub-100-millisecond latency, which makes live coding practical. Beyond the REPL, henri compiles to standalone Jack clients, Pure Data externals, SuperCollider UGens, WebAssembly modules, and an embeddable C library for host applications. This report documents the core of the language, its numerical implementation, and its compilation targets. Five worked examples (damped harmonic oscillator, additive bank of harmonic oscillators, Lorenz attractor as sound source, Karplus–Strong plucked string, Kuramoto network of coupled phase oscillators) and two annotated LLVM IR listings (the explicit symplectic integration step of a 2-D oscillator; the per-sample Newton–Raphson loop solving the implicit midpoint step for a state-variable filter) are included as appendices. The report is intended as a citable reference for papers and artistic works using henri. This is version 1.0.0; subsequent versions will be deposited under the same Zenodo concept DOI.
David Pirrò (Tue,) studied this question.