My name is Christopher Bertels and I’m a student at the University of Osnabrück. I study Computer Science and Philosophy.

I’ve written a bunch of free software, most of which you can find on my GitHub profile.

I’m also on Twitter:

Hobbies & Interests

I’ve been interested in programming language design and implementation for a long time. I prefer dynamic over static languages. I prefer implicit over explicit. Here’s a list of languages I like and have used:

  • Fancy (see below)
  • Ruby
  • Common Lisp
  • Clojure
  • Smalltalk

Other languages I have used and have a working knowledge of:

  • C
  • C++
  • C#
  • Java
  • Python

Languages I’ve tried out and liked:

  • Erlang
  • Haskell

Apart from these I’ve played with many other languages, but did not write anything significant in them.


In my spare time I work on a new general-purpose programming language called Fancy. I started working on Fancy in January 2010 and have been working on it ever since.

This blog mostly talks about its development, new features and ideas related to it. Fancy runs on Rubinius, a Ruby VM, and is mostly inspired by Smalltalk, Ruby and Io.

It’s a pure dynamic object-oriented programming language, with built-in support for concurrency (via Futures and Actors) and has first-class integration support for Ruby and any Ruby library, including all Ruby C-extensions supported by Rubinius.

Talks I gave

This is a list of talks I gave on Fancy:






Work experience

In 2011, I did a 1 year internship at BackType and Twitter in San Francisco.

My internship started at BackType in January 2011 and was extended from 4 months to a full year. In July 2011 BackType got acquired by Twitter, and I joined Twitter with the rest of the BackType team.

I led the web development part of Twitter’s new Web Analytics app that our team of ex-BackType members worked on, among lots of other things.