Effect Handler Oriented Programming

Effect handlers allow programmers to define, customise, and compose a range of crucial programming features ranging from concurrency to probability, inside the programming language. EHOP will develop a radical new programming paradigm called Effect Handler Oriented Programming (or EHOP for short). EHOP will empower software developers to build modular interactive software, enabling the development of safe, secure, and reliable applications. As well as developing the theory and practice of effect handler oriented programming, EHOP will add effect handlers to systems as diverse as WebAssembly, the new target language for the web, and Hack, the language in which the Facebook app is written.

EHOP is led by Sam Lindley at The University of Edinburgh and is funded by a £1.45M UKRI Future Leaders Fellowship (MR/T043830/1) between February 2021 and January 2025.

Sam Lindley

Principal Investigator
Anton Lorenzen

Researcher
Cristina Matache

Researcher
Frank Emrich

Researcher
Jesse Sigal

Researcher
Wenhao Tang

Researcher
Orpheas van Rooij

Researcher

Visiting researchers

J. Garrett Morris

University of Iowa
Robin Jourde

ENS de Lyon
Yi Zhou

The University of Edinburgh
Nachi Valliappan

Chalmers University of Technology

Papers

- Effect handlers for C via coroutines
  Mario Alvarez-Picallo, Teodoro Freund, Dan R. Ghica, and Sam Lindley
  
  In the proceedings of OOPSLA 2024.
- Oxidizing OCaml with modal memory management
  Anton Lorenzen, Leo White, Stephen Dolan, Richard Eisenberg, and Sam Lindley
  
  In the proceedings of ICFP 2024.
- Asymptotic speedup via effect handlers
  Daniel Hillerström, Sam Lindley, and John Longley
  
  In the Journal of Functional Programming (ICFP 2020 special issue) 34:e5, April 2024.
- Bringing the WebAssembly standard up to speed with SpecTec
- Dongjun Youn, Wonho Shin, Jaehyun Lee, Sukyoung Ryu, Joachim Breitner, Philippa Gardner, Sam Lindley, Matija Pretnar, Xiaojia Rao, Conrad Watt, and Andreas Rossberg
- In the proceedings of PLDI 2024.
- The functional essence of imperative binary search trees
- Anton Lorenzen, Daan Leijen, Wouter Swierstra, and Sam Lindley
- In the proceedings of PLDI 2024.
- Behavioural types for heterogeneous systems
- Simon Fowler, Philipp Haller, Roland Kuhn, Sam Lindley, Alceste Scalas, and Vasco T. Vasconcelos
- In the proceedings of PLACES 2024.
- Asymptotic speedup via effect handlers
- Daniel Hillerström, Sam Lindley, and John Longley
- In the Journal of Functional Programming (ICFP 2020 special issue) 34:e5, April 2024.
- Scoped effects as parameterized algebraic theories
- Sam Lindley, Cristina Matache, Sean Moss, Sam Staton, Nicolas Wu, and Zhixuan Yang
- In the proceedings of ESOP 2024.
- Soundly handling linearity
- Wenhao Tang, Daniel Hillerström, Sam Lindley, and J. Garrett Morris
- In the proceedings of POPL 2024.
- Continuing WebAssembly with effect handlers
- Luna Phipps-Costin, Andreas Rossberg, Arjun Guha, Daan Leijen, Daniel Hillerström, KC Sivaramakrishnan, Matija Pretnar, and Sam Lindley
- In the proceedings of OOPSLA 2023.
- Structural subtyping as parametric polymorphism
- Wenhao Tang, Daniel Hillerström, James McKinna, Michel Steuwer, Ornela Dardha, Rongxiao Fu, and Sam Lindley
- In the proceedings of OOPSLA 2023.
- Separating sessions smoothly
- Simon Fowler, Wen Kokke, Ornela Dardha, Sam Lindley, and J. Garrett Morris
- In LMCS, Volume 19, Issue 3, July 2023
- High-level effect handlers in C++
- Dan Ghica, Sam Lindley, Marcos Maroñas Bravo, Maciej Piróg
- In the proceedings of OOPSLA 2022.
- Constraint-based type inference for FreezeML
- Frank Emrich, Jan Stolarek, James Cheney, and Sam Lindley
- In the proceedings of ICFP 2022.
- Separating sessions smoothly
- Simon Fowler, Wen Kokke, Ornela Dardha, Sam Lindley, and J. Garrett Morris
- In the proceedings of CONCUR 2021.
- [extended version]
- Handler calculus
- Sam Lindley
- Extended abstract. Presented at HOPE 2021.
- Composing UNIX with effect handlers: A case study in effect handler oriented programming
- Daniel Hillerström
- Extended abstract. Presented at ML Family Workshop 2021.

Theses

- Implementing UNIX with effect handlers
- Ramsay Carslaw
- Undergraduate thesis, School of Informatics, The University of Edinburgh, 2024.
- Complete and easy type inference for first-class polymorphism
- Frank Emrich
- PhD thesis, School of Informatics, The University of Edinburgh, 2023.
- Concrete sheaf models of higher-order recursion
- Cristina Matache
- PhD thesis, Department of Computer Science, University of Oxford, 2023.
- Foundations for programming and implementing effect handlers
- Daniel Hillerström
- PhD thesis, School of Informatics, The University of Edinburgh, 2021.

Talks

- Effect handler oriented programming
- Sam Lindley
- Nanyang Technical University Singapore, November 2024
  - .
- Soundly handling linearity
- Wenhao Tang
- POPL 2024, January 2024
  - .
- University of Bristol, October 2023
  - .
- EHOP workshop, July 2023
  - .
- An algebraic theory of named threads (work in progress)
- Cristina Matache
- GALOP workshop, January 2024
  - .
- Scoped effects as parameterized algebraic theories
- Cristina Matache
- Invited talk at the Directions and Perspectives in the λ-calculus workshop, January 2024
  - .
- SPLS, November 2023
  - .
- Status update on WasmFX implementation in Wasmtime
- Frank Emrich
- WebAssembly Stack Switching Subgroup, December 2023
  - .
- Structural subtyping as parametric polymorphism
- Wenhao Tang
- OOPSLA 2023, October 2023
  - .
- Tracking linear continuations for effect handlers
- Wenhao Tang
- Huawei-Edinburgh Joint Lab Workshop, June 2023
  - .
- SPLS, March 2023
  - .
- High-level effect handlers in C++
- Sam Lindley
- OOPSLA 2022
- Huawei Edinburgh Joint Lab Workshop, January 2023
- Asymptotic Speedup via Effect Handlers
- Daniel Hillerström
- FATA seminar, December 2022
  - .
- WasmFX: Structured Stack Switching via Effect Handlers in WebAssembly
- Daniel Hillerström
- Wasm Research Day, October 2022
- Huawei Edinburgh Joint Lab Workshop, January 2023
- Effect handler oriented programming
- Sam Lindley
- Huawei strategy and technology workshop, September 2022
  - .
- Concrete categories and higher-order recursion (With applications including probability, differentiability, and full abstraction)
- Cristina Matache
- LICS, August 2022
  - .
- Effect handlers for WebAssembly
- Sam Lindley
- Formal Wasm Meeting 2022, Newton Institute, Cambridge
  - .
- Effect handler oriented programming
- Sam Lindley
- SPLV 2022
  - .
- Effect handlers for WebAssembly
- Sam Lindley
- MFPS 2022 (invited talk)
  - .
- Effect handler oriented programming
- Sam Lindley
- OPLSS 2022 (summer school course)
- On the expressive power of types
- Sam Lindley
- TYPES 2022 (invited talk)
  - .
- Composing UNIX with Effect Handlers: An Introduction to Effect Handler Oriented Programming
- Daniel Hillerström
- Microsoft Research, Redmond, WA, USA, May 26, 2022
- Huawei Research Centre, Zurich, Switzerland, October 13, 2022.
- Effect Handler Oriented Programming
- Sam Lindley
- Huawei-Edinburgh Joint Lab, December 10, 2021
  - .
- Handlers.Js: Compiling Effect Handlers to JavaScript
- Daniel Hillerström
- Tarides, November 16, 2021
  - .
- Wasm with typed continuations continued
- Sam Lindley
- Wasm Stacks Subgroup, November 1, 2021
  - .
- WasmFX: Typed Continuations in Wasm
- Daniel Hillerström
- SPLS October 2021
  - .
- Typed Continuations: A Basis for Stack-switching in Wasm
- Daniel Hillerström
- Wasm Stacks Subgroup, September 20, 2021
  - .
- Handler Calculus
- Sam Lindley
- Dagstuhl Seminar 21292
- HOPE 2021
  - .
- Composing UNIX with Effect Handlers: A Case Study in Effect Handler Oriented Programming
- Daniel Hillerström
- Dagstuhl Seminar 21292
- ML Family Workshop 2021
  - .

Posters

- Session-typed effect handlers (work in progress)
- Wenhao Tang
- Student Research Competition of POPL 2024, January 2024
  - .
- 3rd place in the graduate category.

Effect Handler Oriented Programming

PhD positions

People

Core team

Project partners