Felix Mulder

Computer Science Engineer


  • felix.mulder[at]gmail.com


  • October 16, 1990


  • Research Fellowship
  • Languages and Programming Methods Laboratory
  • EPFL, Switzerland
  • 03.2016-05.2016
  • Master of Science
  • Computer Science Engineering
  • Lund University, Sweden
  • 2011-2016
  • Foreign Exchange
  • Ikubunkan Yumei Gakuen
  • Tokyo, Japan
  • 2008-2009


  • Swedish native
  • English full professional
  • French elementary
  • Japanese elementary





I work in developer productivity. My main area of focus is making sure that merges to Stripe's monorepos is able to scale with the growth of our engineering force.

We're looking at having hundreds of concurrent merge submissions per hour. To do this we've implemented speculative builds in order to keep a, de facto, always green main branch.

Klarna Bank AB


STOCKHOLM, SWEDEN 09.2017-09.2020

Led teams that developed the capabilities for interledger transactions and banking infrastructure on a modern banking platform developed using functional languages and cloud technologies.

Taught functional programming in Haskell/Scala to Klarna's engineers and served as an adviser to various teams on Scala and functional programming related solutions.

École Polytechnique Fédérale de Lausanne



Implemented the Scala 3 REPL, featuring lots of modern features like tab-completion, syntax highlighting and more.

Implemented semantic error reporting to allow for amazing error messages that tell you what went wrong, offer fixes and give concrete suggestions using your own code as example.

Wrote a documentation compiler - and enabled it to be much more than just creating API reference. It is a full-blown static site generator, where you can cross reference between code and documentation; which makes sure that you both cater to your users and contributors - without duplication.

As release manager, I implemented a release strategy, based on Rust's train model. I also gave several talks on Scala 3, kept the community engaged via workshops and hackathons.

Google Summer of Code

Mentor for Scala Organization


Mentoring student on improvements to documentation compiler. Including type-safe templating engine and compiled documentation, ensuring that any code-snippet is always up-to-date with the released code.

Google Summer of Code

Scala Organization


Implemented the next generation documentation tool, alias dottydoc, for Scala. Improvements over the old scaladoc include a full Scala stack from runnable binary to client JavaScript using Scala.js

École Polytechnique Fédérale de Lausanne

Research Fellow, Programming Methods Laboratory


Working on the next generation Scala compiler, and the tooling surrounding it. This compiler would later go on to become the Scala 3 compiler.

The majority of the work consisted of identifying analyzing and xing issues in the compiler. Major contributions include partial evaluation of statically known function results, implementing a REPL based on Ammonite and laying the groundwork for the next generation documentation tools for Scala.

Axis Communications AB

Student Software Engineer, Core Technologies

LUND, SWEDEN 2014-2016

Master's Thesis: Image Processing Across Multiple Interconnected System-on-Chips

Developed a Linux kernel performance indexing framework, measuring relative performance difference in key parts of the kernel using Python.

Implemented reference counting in Axis's video memory driver for debug purposes. It identified a potential deadlock on its first day of service.

Researched and implemented GPU use cases for Axis's embedded systems using C and OpenGLES.

Built a system for cataloging and maintaining test data. Making more than a terabyte of data not previously cataloged, searchable.

Sole Proprietor

Software Engineer and Consultant

LUND, SWEDEN 2012-2015

Developed an ordering system and API for Malmö's largest taxi company using Scala, Akka and PostgreSQL. Enabling users to order cabs and track their location in real time.

Developed the second version of the taxi company's iOS app.

Project manager for iOS & Android development on taxi apps.

Lund University: Computer Sc. Dept.

Teacher's Assistant and Lab Manager

LUND, SWEDEN 2012-2015

Data Structures, Abstraction and Design using Java

Programming and Databases

Computer Organization, taught students the basics of computer architecture, assembly and real time systems.


Software Developer, Web Applications & Services

MALMÖ, SWEDEN 2012-2013

Developed the companion app and backend for a coffee bar and startup incubator. Enabling booking of meeting rooms, ordering products from the bar, Wi-Fi access as well as invoicing.

Webmaster and developer for the daily newspaper Skånska Dagbladet


Programming Languages

Scala, Haskell, Java, C, Python, C++14, PureScript, JavaScript

Other Skills

Linux, Mac OS, AWS, PostgreSQL, Kafka, Reactive Programming, TDD, DDD, Spark, TCP/IP, Agile, git, REST, React


  • Program Committee Erlang Workshop ICFP 2019
    • https://icfp19.sigplan.org/home/erlang-2019
  • Compiler Team Member of dotty
    • https://github.com/lampepfl/dotty
  • Contributor to Stylish-Haskell, migrated code formatting to use the GHC Haskell compiler's parser (PR)
  • Contributor to Scala: key contributor to the 2.12 Scaladocs tool
    • Getting into Scaladoc Development featured on Scala-lang.org:http://bit.ly/1r8m90Z
    • https://github.com/scala/scala
  • Maintainer of purescript-spec a testing framework inspired by Haskell's hspec
    • https://github.com/purescript-spec
  • Contributor to the cats category theory and functional programming library for Scala
    • https://github.com/typelevel/cats


  • Competed in Swedish Espresso Brewing Championship and placed 8th
  • Worked as chief of QA, machine engineer and group leader for the coffee tents at the university carnival, Lundakarnevalen. The carnival involves 6000 students and attracts over 400000 visitors


Available upon request