Research

I am an assistant professor in the Programming Languages and Software Technology research group at Uppsala University, working on programming languages, semantics and type systems. I am currently involved in the following projects:.

• Verona, a new programming language for infrastructure programming, featuring a novel concurrency model called behaviour-oriented concurrency with a co-designed type system.
• Trieste, a DSL for experimental development of multi-pass compilers, featuring built-in support for property-based testing.
• Miking, a framework for rapid development of domain-specific languages based on composition of language fragments, featuring parsing with statically resolvable ambiguity.

I used to be a post-doc researcher in David Broman’s group at KTH, working on heterogeneous model compilers and semantics, as well as full-stack verification of programs synthesized from timed automata.

I did my PhD with Tobias Wrigstad and Dave Clarke at Uppsala University. There, I did research on type systems for controlling aliasing and preventing data-races in concurrent and parallel programs.

In 2018, I did an internship at Microsoft Research in Cambridge, working together with Matthew Parkinson and David Chisnall on compiler-based mitigation of the Spectre attacks.

I was one of the main contributors to Encore, a highly concurrent object-oriented programming language. Encore’s type system guarantees the absence of data-races and is based on my work on Kappa.

I am always interested in discussing collaboration!

Publications and Presentations

• [2024] Trieste: A C++ DSL for Flexible Tree Rewriting – SLE’24 (paper)
• [2024] Arrays in Practice: An Empirical Study of Array Access Patterns on the JVM – Programming’24 (paper)
• [2024] Encore: Coda – Springer Nature (paper)
• [2023] Reference Capabilities for Flexible Memory Management – OOPSLA’23 (paper)
• [2023] Statically Resolvable Ambiguity – POPL’23 (paper|artifact)
• [2021] Resolvable Ambiguity: Principled Resolution of Syntactically Ambiguous Programs – CC’21 (paper)
• [2020] Reference Capabilities for Safe Parallel Array Programming – Programming’20 (paper)
• [2019] Developing a Monadic Type Checker for an Object-Oriented Language: An Experience Report – SLE’19 (Distinguished Artifact Award) (preprint|artifact)
• [2019] Progress Report: Exploring API Design for Capabilities for Programming with Arrays – ICOOOLPS’19 (paper)
• [2018] OOlong: a concurrent object calculus for extensibility and reuse – ACM SIGAPP (paper | artifact)
• [2018] Attached and Detached Closures in Actors – AGERE@SPLASH’18 (paper | slides)
• [2018] Cflat: A New Modular Approach to Implementing Efficient and Tunable Collections – Onward! (paper)
• [2018] Bestow and Atomic: Concurrent Programming using Isolation, Delegation and Grouping – JLAMP (paper)
• [2018] Parallel programming with arrays in Kappa – ARRAY@PLDI’18 (paper)
• [2018] Forward to a Promising Future – COORDINATION’18 (Best Paper Award) (paper)
• [2018] Capability-Based Type Systems for Concurrency Control – PhD Thesis (extensive summary)
• [2017] OOlong: An Extensible Concurrent Object Calculus – OOPPS@SAC’17 (preprint | slides | artifact)
• [2017] Reference Capabilities for Concurrency & Scalability: an Experience Report – OCAP’17 (slides | video forthcoming)
• [2017] Mastery Learning-Like Teaching with Achievements – SPLASH-E’17 (paper)
• [2017] Relaxed Linear References for Lock-Free Data Structures – ECOOP’17 (paper and talk | slides)
• [2017] Actors without Borders: Amnesty for Imprisoned State – PLACES’17 (paper | slides)
• [2016] Reference Capabilities for Trait Based Reuse and Concurrency Control – Technical Report (paper)
• [2016] Types for CAS: Relaxed Linearity with Ownership Transfer – NWPT’16 (paper)
• [2016] LOLCAT: Relaxed Linear References for Lock-free Programming – Technical Report (paper)
• [2016] Reference Capabilities for Concurrency Control – ECOOP’16 (paper and talk | slides | poster)
• [2016] Kappa: Insights, Current Status and Future Work – IWACO’16 (paper | slides)
• [2015] Refined Ownership: Fine-grained controlled internal sharing – SFM’15 (paper)
• [2015] Parallel Objects for Multicores: A Glimpse at the Parallel Language Encore – SFM’15 (paper)
• [2014] Capable: Capabilities for Scalability – IWACO’14 (paper | slides)

Community Service

• [2025] Programming’25, student research competition jury
• [2025] MoreVMs’25, reviewing
• [2025] GulFest, reviewing
• [2024] JLAMP, reviewing
• [2024] TCPS, reviewing
• [2024] SLE’24, program committee
• [2024] IWACO’24, program committee
• [2024] Programming’24, student research competition jury
• [2023] ICOOOLPS’23, program committee
• [2023] VIMPL’23, program committee
• [2023] IWACO’23, program committee
• [2023] PLACES’23, program committee
• [2022] SCP, reviewing
• [2021] SPLASH’21, student research competition jury
• [2021] SLE’21, artifact evaluation co-chair
• [2021] AGERE’21, member of the organizing committee.
• [2020] AGERE’20, member of the organizing committee.
• [2020] OOPSLA’20 Artifact Evaluation Committee.
• [2020] PLDI’21 Artifact Evaluation Committee.
• [2019] AGERE’19, member of the organizing committee.
• [2019] LCTES’19 Artifact Evaluation Committee
• [2019] PLDI’19 Artifact Evaluation Committee
• [2018] ECOOP’18 Artifact Evaluation Committee
• [2018] PLDI’18 Artifact Evaluation Committee
• [2017] OOPSLA’17 Artifact Evaluation Committee
• [2017] IWACO’17, co-chair and organizer together with Juliana Franco.
• [2017] ECOOP’17 Artifact Evaluation Committee
• [2017] Subreviewing for ECOOP and OOPSLA
• [2016] OOPSLA’16 Artifact Evaluation Committee
• [2016] Subreviewing for ECOOP and OOPSLA
• [2015] Subreviewing for PLDI, ECOOP, OOPSLA, CONCUR and SAC
• [2014] ECOOP’14, local student aid

Teaching

Since 2021 I am the main teacher of a second year 20 ECTS credits course at Uppsala University called Imperative and Object-Oriented Programming Methodology (or IOOPM for short). In 2021 I was the proud recipient of the Union of Engineering and Science Student’s Teaching Award!

Since 2023 I also teach a 5 ECTS credit course on Programming Language Semantics.

Previous courses taught include:

• Computer Hardware Engineering (7.5 ECTS, KTH), 2019
• Program Design and Data Structures (20 ECTS, UU), 2016-2017
• Imperative and Object-Oriented Programming Methodology (20 ECTS, UU), 2012-2018

Students

I am the main supervisor of the following PhD students:

• Matilda Blomqvist (since 2023)

I am the co-supervisor the following PhD students:

• Ellen Arvidsson (since 2021)

I have supervised the following PhD students to completion:

• Viktor Palmkvist (co-advisor, graduated 2024)
• Beatrice Åkerblom (main advisor, graduated in 2025)

I am currently supervising the following bachelor thesis projects:

• Hugo Lönnqvist Österberg
• Richard Widén

I have supervised the following master thesis projects:

• Alfrida Mattisson – Automatically Choosing Implementations of Abstract Data Types

I have supervised the following bachelor thesis projects:

• Gustav Lundin – Pattern Matching in Encore
• Christian Törnqvist – Finding Patterns in Lock-Free Algorithms
• Joel Wallin – Implementing Safe Sharing Features in Encore
• Jonas Olander – Separate Compiling for Encore
• Tage Johansson – A Strongly Typed Shell with Full Control over Side Effects
• Victor Odebäck – CTriPio: Developing an Intermediate Representation of C code in Trieste for Static Analysis

Personal

I spend a lot of my free time on listening to and creating music.

• From 2008 to 2017 I was the conductor of Kalmar Nation’s Choir in Uppsala. Here is a video of us performing of Vienna Teng’s beautiful Hymn of Acxiom.
• Since 2015 I am a singer in Uppsala Vokalensemble.
• I also like to write and arrange choir music. Here is a recording of my arrangement of the traditional Swedish hymn “Den blomstertid nu kommer”. You can also buy the arrangement! Here is a recording of my setting of Alfred Tennyson’s Now Sleeps the Crimson Petal, performed by the women’s choir Discordia.
• I play the electric and upright bass. Here is a recording I made as a Christmas present for the friend who introduced me to the wonderful music of Vulfpeck.
• I play bass in the now dormant band Morfis. Our album Dunia from 2013 is on Spotify! I wrote and arranged the songs Gånglåt från Gottsunda (“Walking Song from Gottsunda”), Cykeltjuven (“The Bicycle Thief”) and Kometen (“The Comet”).

I like to play Geoguessr. Here is a presentation I did about the kinds of things you can look for when playing.