Home

This is the personal website of myself, Manuel Bärenz. You will find information about all sorts of things I do on these pages. I speak German, English and a bit of Spanish. Currently, I live in Berlin.

I work for sonnen eServices GmbH as senior software engineer, on optimization algorithms, machine learning, simulation and data analysis in the Algorithms & Research team of sonnen's Virtual Power Plant.

In 2023 I was Open Source Fellow at Tweag and developed a library for reactive Bayesian machine learning, rhine-bayes.

You can find my current CV here.

Computer Science

My main interests are functional, type-driven, reactive programming. I love type theory, especially when involving dependent types, session types, and effect systems. My main languages are Haskell, Nix, Idris and Agda, but I've picked up a lot of Rust and Elixir on work as well. I taught Haskell at University Bamberg. I've published on Functional Reactive programming (FRP), and still work and contribute in that area. Some hobby projects include Bayesian reasoning, verification of reactive programs with side effects, parser combinators, monad transformers, and toy languages. (I used to program in Python, Perl, CoffeeScript/NodeJS, C++, PHP and Delphi, but I wouldn't touch any of these again.)

Publications

Peer-reviewed

• Rhine: FRP with Type-Level Clocks, Haskell Symposium 2018. With Iván Pérez.
• Functional Reactive Programming, Refactored, Haskell Symposium 2016. With Iván Pérez and Henrik Nilsson.

Abstracts and pre-prints

• Verifying Functional Reactive Programs with Side Effects, TYPES 2017. With Sebastian Seufert.
• The essence of live coding: Change the program, keep the state!, Haskell Symposium 2019.

Maths

I studied physics and maths. I'm interested in quantum gravity and differential topology, and worked in this field as a PostDoc, using category theory and topological quantum field theory.

A short CV:

Some of my mathematical works:

• Topological state sum models in four dimensions, half-twists and their applications (PhD thesis), University of Nottingham.
• Dichromatic State Sum Models for Four-Manifolds from Pivotal Functors, Communications in Mathematical Physics. With John Barrett.
• Evaluating TQFT invariants from G-crossed braided spherical fusion categories via Kirby diagrams with 3-handles, arXiv Preprints.
• Cartan Geometry and Spin Networks, Universität Heidelberg.

Formalising 4-manifold diffeomorphisms with graphical calculus of higher categories and the Globular theorem proving assistant. (Further information here.)

I also worked on half-twists in braided categories and quantum groups.

Music

I'm a classically trained pianist, but I mainly do improvisation these days. You can find recordings of some of my improvisations on Bandcamp.

I play and accompany improv theatre in Bamberg, with Pipperlapupp. I used to accompany improv theatre in the Berlin area, for example at BühnenRausch. I co-founded a musical improv theatre group in Vienna, TonArt.

I'm an experienced choir singer, and I sing in the musica-viva-chor Bamberg. In 2024, we are premiering my first concert-length piece for choir, Gilgamesch. I composed it and will conduct the choir.

I also compose music for theatre, usually piano solo scores which I perform myself, but also songs, musical pieces, as well as orchestral, choir and ensemble works. Past compositions include original scores for “Whose life is it anyways?” and “A Midsummer Night's Dream”.

I sometimes lead project ensembles, for example vocal a-capella ensembles (jazz and classical) or big bands, for example at the Max-Weber-Programm or the CdE.

If you want to book me as a pianist, or you would like me to compose a score for you, please send an email to music@(insert my domain name here).