In GSoC 2026

Haskell.org

Haskell is an advanced, general-purpose, purely functional programming language. It has a strong, static type system with Hindley-Milner type inference.

Ideas list Website

Contributors in 2026

Same as 2025

Projects since 2016

9.3 a cycle on average

Cycles

8 of 11

3-cycle streak

Rank in 2026

#91

of 183, 0.4% of slots

Mentors

for 4 projects in 2024

Contributors per cycle

Accepted projects each year, against the median organization that year

View as table

Haskell.org contributors per cycle
	Haskell.org	Median organization
2016	0	4
2017	0	4
2018	15	3
2019	15	4
2020	12	4
2021	10	4
2022	10	3
2023	0	4
2024	4	4
2025	4	5
2026	4	4

Stack and topics

Each one has its own page of organizations and trends

Programming languages Functional-programming Education Compilers Haskell Functional programming Build tools #compilers #programming-tools #functional-programming #programming-languages #education Programming tools

More about Haskell.org

The language natively supports lazy evaluation, and lets you track side effects in the type system. This leads to a concise and declarative style of programming, which differs quite a bit from conventional languages. By controlling side effects and working with immutable data, the programmer can avoid whole classes of bugs.

Haskell generally compiles to fast, native code, but it can also be compiled to other targets like JavaScript (through GHCJS) or LLVM.

In Google Summer of Code, we attempt to improve not only the language, but the whole ecosystem. This includes (aside from the language itself):

- Compilers - Commonly used libraries - Commonly used applications written in Haskell - Profilers, debuggers and other tools - Package managers and infrastructure

Quick answers

Is Haskell.org in GSoC 2026?: Yes, with 4 contributors.
How long has it taken part?: 8 of 11 cycles since 2016, first in 2018, with a 3-cycle streak running.
How many contributors does it usually take?: 9.3 a cycle on average, 74 in total. Its largest cycle was 2018, with 15.
What does it build with?: Haskell, Ghc, Cabal, Codeworld, Servant, Compiler.

Accepted projects

4 projects in 2026 · All 74 projects since 2016

xeus-haskell -- GHC/Wasm Backend Integration Prototype
Arman Sanjay Choudhary
This project aims to integrate the official GHC/WebAssembly backend into xeus-haskell, a Jupyter kernel for Haskell. Currently, the kernel relies on...
Project
Case split plugin
Aster89
The goal of this proposal is to extend HLS with a new plugin, the case split plugin, which provides a new code action (or possibly more of them) for...
Project
Restoring Typeclass Refinement Support in LiquidHaskell
Juan Pablo Yamamoto
LiquidHaskell is a verification tool that allows Haskell developers to prove the correctness of their code through refinement types. This proposal...
Project
Goto dependency definition
vidit
Haskell Language Server (HLS) currently supports Goto Definition only for symbols defined within a user’s project, making it difficult to inspect...
Project

Improve HLS Support for Record-Dot-Syntax
ColtenMentored by Michael Peyton Jones, Dom Mills
For GHC 9.2.x to achieve more widespread adoption, tooling will need to support its best features. For years users have been frustrated by Haskell's...
Project Report
[Haskell.org] Support more LSP features in Haskell Language Server
Aarush Bhat (sloorush)Mentored by Michael Peyton Jones
This project proposes various new features for the haskell language server(HLS). While HLS already comes with the most important ones, a few haven’t...
Project Work
Operating Chrome with Haskell
Arsalan CheemaMentored by Jasper Van der Jeugt, Albert Krewinkel
The Chrome DevTools Protocol (CDP) serves a variety of automation use cases by providing programmatic access to Chrome. These include data...
Project Code
Modularizing GHC
Dominik PetelerMentored by Ericson2314
The architecture of the GHC compiler in its current state is anti-modular. Designed with GHC-the-program as the sole consumer in mind, it is very...
Project Code
Hackage - Package Rank
KubanekOMentored by Gershom
hackage-server as of yet does not support more advanced algorithm for sorting relevant packages (at the moment user rating is used), this proposal...
Project Report
MMTk Port for GHC: An alternative of the current GHC storage manager
Junming ZhaoMentored by Dom Mills, Ben Gamari
The proposed project aims at establishing a port between GHC and [MMTk](https://www.mmtk.io/) -- an external memory management toolkit that provides...
Project Code
Implementing a GPU Backend for Advanced Machine Learning Algorithms
Zarak MahmudMentored by Sacha Sokoloski, Junji Hashimoto
This project enhances Goal - a library of machine learning algorithms based on Haskell - with a GPU backend provided by Hasktorch. Goal strikes a...
Project Report
New Hackage Features
Alias QliMentored by Gershom
This proposal aims to add new features to the Hackage server, mainly include package sorting, user info update and user notification emails. It's...
Project Code

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reimplement `cabal check`
Francesco AriisMentored by Jasper Van der Jeugt, Andreas Abel
`cabal check` is a tool to check the correctness of a `.cabal` file and more generally to provide more useful output (warnings, especially related to...
Project Work
Formalising Konnakol using Haskell
Aravind MohandasMentored by Alex McLean
Konnakol, in South Indian Carnatic music, is the art of performing percussion syllables vocally. However, notwithstanding its importance in Carnatic...
Project Report

Enhanced figure support in pandoc
Aner LuceroMentored by tarleb
Figures play a central role in the life cycle of all kinds of research and analysis. That is: The communication of results. What we propose in this...
Project Report
Gradually Typed Hasktorch
Julius MarozasMentored by Torsten Scholak
Hasktorch has two distinct APIs for tensors: Torch.Tensor and Torch.Tensor.Typed. While the untyped version can initially be easier to use and...
Project Summary
Fixing ihaskell-widgets
David DavóMentored by James Brock, Vaibhav Sagar
While mainly used in data science, Jupyter Notebook’s interactivity makes it a great tool for teachingand learning new concepts and programming...
Project Report
Haskell in CodeMirror 6
Olivian CretuMentored by Chris Smith
CodeMirror 6 is an editor which supports many programming languages. However, it lacks first-class language support for Haskell. The Abstract Syntax...
Project Code
Visualization Libraries for ghc-debug
Ethan Tsz Hang KiangMentored by Matthew Pickering
"ghc-debug" is a heap profiler tool for GHC that pauses the current program and lets you run your own custom analyses on the heap. My proposal is to...
Project Report
Support call hierarchy in Haskell Language Server
Lei ZhuMentored by Javier Neira, Pepeiborra
This proposal aims to add call hierarchy support in Haskell Language Server(HLS). Language Server Protocol(LSP) has supported call hierarchy in 3.16,...
Project Code
TOML Support in dhall-haskell
Julio GrilloMentored by Simon Jakobi, Gabriel Gonzalez
This is a proposal to add serialization and deserialization support for TOML in the functional configuration language Dhall. TOML is a relatively new...
Project Summary
TidalCycles API and editor plugin
Martin GiusMentored by Alex McLean
TidalCycles is an Embedded Domain Specific Language for pattern, in use by 10,000s of musicians worldwide. However it has had little work done on the...
Project Code

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Dhall bindings to TOML configuration language
Marcos LeronesMentored by Simon Jakobi, Gabriel Gonzalez
Dhall is a programmable configuration language that uses functions, types and imports to make readable configuration files easily. Right now, Dhall...
Project Report
Haskell Language Server: Symbol Renaming
Oliver MadineMentored by Pepeiborra
The Haskell Language Server is a popular, comprehensive Haskell IDE; however, it is yet to implement a core feature: symbol renaming. With the recent...
Project Summary

Multiple Home Packages for GHC
fendorMentored by Zubin Duggal, John Ericson, Matthew Pickering
Haskell tooling has improved considerably over the last year. Haskell IDE Engine was able to build a user-base that is happy with the feature set....
Project Summary
`SPECIALIZABLE` GHC pragma
Francesco Gazzetta @fgazMentored by CarterSchonwald, Andreas Klebinger, chessai
The main task of this project is the addition of a SPECIALIZABLE pragma to GHC, that will have the effect of exposing an unfolding of the marked...
Project Code
Functional Machine Learning Algorithms for Music Generation
Elizabeth WilsonMentored by Austin Huang, Torsten Scholak, Alex McLean
The proposed outcome of this Summer of Haskell research is the production of a library or package for live coding autonomous music through...
Project Work
Custom Dataloader for Hasktorch
Andre DapratoMentored by Austin Huang, Adam Paszke, Torsten Scholak +1
Hasktorch is an important project for showcasing what a strong type system andfunctional programming can bring to machine learning tasks. The...
Project
Finish the package candidate workflow for Hackage
Sitao ChenMentored by hvr, Gershom Bazerman
Currently, the package candidates are not using the templating system and their UI can be improved. To improve the candidates publishing process, we...
Project Report
Number Field Sieves
Federico BongiornoMentored by Sergey Vinokurov, Andrew Lelechenko
This proposal aims to implement efficiently the quadratic sieve and the general number field sieve in Haskell while producing a mathematically...
Project Code
Building the Haskell Language Server and more
lukelauMentored by Alan Zimmerman, Pepe Iborra, Zubin Duggal
After a busy couple of days at the Bristol Hackathon, the developers behind ghcide and haskell-ide-engine merged efforts resulting in an exciting...
Project Summary
Documentation generator for the Dhall configuration language
German RobayoMentored by Profpatsch, Gabriel Gonzalez, sjakobi
Actual Problem Dhall is a programmable configuration language. Despite as haskell programs which have haddock as a documentation generator tool,...
Project Report

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Add primops to expand the (boxed) array API
buggymcbugfixMentored by andrewthad, Andreas Klebinger, chessai
GHC is an industry-strength compiler for Haskell. I am proposing to add primitives that allow more efficient operations involving immutable...
Project Code
Update stylish-haskell to use ghc-lib-parser
Beatrice VerganiMentored by Jasper Van der Jeugt, lukaszgolebiewski, Paweł Szulc
Stylish-haskell is a code prettifier that formats Haskell programs relying on the haskell-src-exts library to parse the Haskell code into an AST. ...
Project Code
Build-integration and Badges for Hackage
Shubham AwasthiMentored by hvr, Gershom Bazerman
Hackage have a dedicated Builder application which builds the package, documentation and report same to the hackage server. While this information...
Project Report
Optimising Haskell developer tool performance using OpenTelemetry
mpardalosMentored by Dmitry Ivanov, Matthew Pickering
The Haskell developer tool ecosystem, while greatly improving in recent years, has a performance problem. Haskell IDE Engine (HIE), the most popular...
Project Code

Issue-Wanted Web Application
Rashad GoverMentored by Veronika Romashkina, Dmitrii Kovanikov
Issue-wanted is a web application focused on improving the open source Haskell community. It does so by centralizing and categorizing GitHub issues...
Project Report
Improving HsYAML Library
Vijay TadikamallaMentored by Herbert Valerio Riedel, Michał Gajda
HsYAML is a pure Haskell idiomatic implementation of the YAML 1.2 data serialization language with a strong emphasis on compliance with the YAML 1.2...
Project Report
Improving Hackage Matrix Builder as a Real-world Fullstack Haskell Project
Andika Riyandi (Rizary)Mentored by Herbert Valerio Riedel, Robert Klotzner
Finding the best example of full-stack Haskell web development project is hard as a beginner to intermediate Haskell developer. This is based on my...
Project Code
Putting hie Files to Good Use
Zubin DuggalMentored by Alan Zimmerman, Matthew Pickering
A collection of small to medium length tasks which will improve the Haskell editor tooling experience, as a continuation of my work on GSOC18 and...
Project Code
Upgrading hs-web3 library
amany9000Mentored by Alexander Krupenkin, Thomas Dietert
Impement a WebSocket layer to hs-web3 and use this WebSocket Functionality to upgrade the current web3 modules and implement an IPFS-Api module using...
Project Code
More graph algorithms for Alga
Vasily AlferovMentored by Andrey Mokhov, Alexandre Moine
The project is about adding some new features to Alga library. This project is on the list of ideas. Briefly about goals: Acyclic graphs I finished...
Project Work
Extending Alga
O V Adithya KumarMentored by Andrey Mokhov, Jasper Van der Jeugt, Alexandre Moine
Alga is a library for algebraic construction and manipulation of graphs in Haskell. Currently there are two main goals, as proposed by Mr. Andrey...
Project Summary
Implementing Chebyshev polynomial approximations in Haskell: Having the speed and precision of numerics with complex, non-polynomial functions.
Deifilia ToMentored by tmcdonell, idontgetoutmuch, Albert Krewinkel
Practically speaking, in science, engineering, and statistics, most computations are done numerically. My project aims to implement a library that...
Project Code

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Hadrian Optimisation
ratherforkyMentored by Andrey Mokhov, Neil Mitchell
Hadrian seeks to replace GHC’s current Make-based build system some time around GHC 8.8, but since the main goal of Hadrian so far has been to...
Project Report
Automated requirements checking as a GHC plugin
Daniel MarshallMentored by Chris Smith, chessai, Alphalambda
The aim of this project would be to create a GHC plugin that allows instructors to define requirements for the code within a project and...
Project Summary
Extending Hasktorch With RNNs and Encoder-Decoder
AdLucemMentored by Austin Huang, Junji Hashimoto, Sam Stites
Project is to build a sequence-to-sequence encoder-decoder model as a module of the Hasktorch library, and demonstrate it on an NLP task.
Project Report
Functional Machine Learning with Hasktorch: Produce Functional Machine Learning Model Reference Implementations
Jesse SigalMentored by Austin Huang, idontgetoutmuch, Junji Hashimoto +1
Neural networks are a powerful tool in machine learning. An integral part of any network is its architecture. However, structuring and comparing new...
Project Code
Property-based testing stateful programs using quickcheck-state-machine
Kostas DermentzisMentored by stevana, stevan, Robert Danitz
Testing software is essential. As a project gets bigger, the difficulty of testing the interactions of all its components increases. Property based...
Project Code
A language server for Dhall
Frederik RamckeMentored by Luke Lau, Gabriel Gonzalez
The aim of the proposed project is to improve support for the Dhall language in mainstream editors via the Language Server Protocol standard.
Project Code
A stronger foundation for interactive Haskell tooling
dxldMentored by Alan Zimmerman, Matthew Pickering
Inevitably new and prospective Haskell users will attempt to obtain editor/IDE integration for Haskell but unfortunately they are much more likely to...
Project Summary

Native-Metaprogramming Reloaded
Shayan NajdMentored by Alan Zimmerman, Ben Gamari
The goal is to continue on an ongoing work, utilising the Trees that Grow technique, to introduce native-metaprogramming in GHC....
Project Code
Benchmarking graph libraries and optimising algebraic graphs
Alexandre MoineMentored by Andrey Mokhov, Alois Cochard
A graph represents a key structure in computer science and they are known to be difficult to work with in functional programming languages. Several...
Project Work
Improvements to GHC's handling of conditionals.
Andreas KlebingerMentored by Joachim Breitner, José Calderón, Ben Gamari
Improvements to GHC's Code Generator Improved code layout In the current approach there is no way to incorporate additional control flow information...
Project Summary
Hi Haddock
Simon JakobiMentored by Herbert Valerio Riedel, Alex Biehl
A long-standing issue with Haskell’s documentation tool Haddock is that it needs to effectively re-perform a large part of the...
Project Report
Improving the GHC code generator
Abhiroop SarkarMentored by carter schonwald, Ben Gamari
This project attempts to improve the native code generator of GHC by adding support for Intel AVX and SSE SIMD instructions. This support would...
Project Summary
Enhancing the Haskell Image Processing Library with State of the Art Algorithms : Project Proposal GSoC, 2018
Khilan RavaniMentored by Alp Mestanogullari
The project proposed here aims to implement different classes of Image processing algorithms using Haskell and incorporate the same to the existing...
Project Report
Functional test framework for the Haskell IDE Engine and Language Server Protocol Library
Luke LauMentored by Alan Zimmerman
The Haskell IDE Engine is a Haskell backend for IDEs, which utilises the Language Server Protocol to communicate between clients and servers. This...
Project Work
Visual Tools and Bindings for Debugging in Code World
Krystal MaughanMentored by Chris Smith, Gabriel Gonzalez
Visual Debugging tools that will allow various ages to interact with and learn visually while tracing their bugs in Haskell
Project Report

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A Library for In-Memory Data Analysis in Haskell
Gagandeep BhatiaMentored by Marco Zocca, Andika D. Riyandi
A typical workflow in interactive data analysis consists of : Loading data (e.g. a CSV on disk) Transforming the data Various data processing stages...
Project Work
Dependently Typed Core Replacement in GHC
Ningning XieMentored by Richard Eisenberg
In recent years, several works (Weirich et al., 2017; Eisenberg, 2016; Gundry, 2013) have proposed to integrate dependent types into Haskell....
Project Report
Making GHC Tooling friendly
Zubin DuggalMentored by Joachim Breitner, Ben Gamari, Gershom Bazerman
GHC builds up a wealth of information about Haskell source as it compiles it, but throws all of it away when it's done. Any external tools that need...
Project Summary
Helping cabal new-build become just cabal build
Alexis WilliamsMentored by Herbert Valerio Riedel, Mikhail Glushenkov
While much of the functionality required to use the new-* commands has already been implemented, there are not-insignificant parts of the design that...
Project Work
Add support for deprecating exports
Alanas PlascinskasMentored by Matthew Pickering, Erik de Castro Lopo
Add support of deprecation pragmas within module exports. This would ease the transition between different versions of the software by warning the...
Project Report
Support for Multiple Public Libraries in a .cabal package
Francesco Gazzetta @fgazMentored by Mikhail Glushenkov, Edward Yang
Large scale haskell projects tend to have a problem with lockstep distribution of packages (especially backpack projects, being extremely granular)....
Project Code
Parallel Automatic Differentiation
Andrew KnappMentored by ekmett, tmcdonell, Alois Cochard +1
Automatic Differentation (AD) is a technique for computing derivatives of numerical functions that does not use symbolic differentiation or...
Project Code

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Data: Google Summer of Code public archive. Contributor counts are accepted projects.

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