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.)

Essence of live coding

This is a live coding framework I developed. I gave a talk about it on Haskell Symposium 2019.

I also gave a small talk about arrows and profunctors at Regensburg Haskell Meetup: Arrows, Monads, Profunctors, Categories, Applicatives, and everything else.


As main author & maintainer

As a main contributor

As a maintainer

  • clay (A CSS preprocessor as embedded Haskell)



Abstracts and pre-prints


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:
2023remoteTweag Open Source Fellowship
2018 - nowBerlin/BambergSenior Software developer at sonnen
2017 - 2018ViennaPostDoc Mathematical Physics
2015 - 2017BambergTeaching Assistant Functional Programming
2013 - 2015NottinghamPhD with John Barrett
2011 - 2012CambridgeMaster in Maths and Theoretical Physics
2008 - 2011Heidelberg, ErlangenBachelor in Physics

Some of my mathematical works:

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.


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).