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ICFP 2019
Sun 18 - Fri 23 August 2019 Berlin, Germany

The Haskell Implementors’ Workshop is a forum for those involved in implementing Haskell systems, infrastructure, libraries and tools, for people generally involved in implementing Haskell technology. We share our work and discuss future directions and collaborations with others.

In 2019, the Haskell Implementors’ Workshop will be co-located with ICFP 2019.

The workshop does not have proceedings. Talks and/or demos are proposed by submitting an abstract and selected by a small program committee. The workshop will be informal and interactive, with a flexible timetable and plenty of room for ad-hoc discussion, demos, and impromptu short talks.

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Fri 23 Aug
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09:00 - 10:00: KeynoteHIW at Elk
09:00 - 10:00
Haskell Use and Abuse at Scale
10:30 - 12:00: MetadataHIW at Elk
Chair(s): Ningning XieThe University of Hong Kong
10:30 - 10:53
Configuration, but without CPP
Matthew PickeringUniversity of Bristol, John EricsonObsidian Systems
10:53 - 11:16
HIE files in GHC 8.8
Zubin Duggal, Matthew PickeringUniversity of Bristol
11:16 - 11:40
Tagging Tags: Inferring the presence of pointer tags at compile time.
11:40 - 12:00
Lightning talks Slot #1
12:00 - 13:30: LunchCatering at Restaurant
13:30 - 15:00: CompilersHIW at Elk
Chair(s): Jose CalderonGalois, Inc.
13:30 - 13:53
Status Update on the Helium for Haskell compiler
Jurriaan HageUtrecht University, Netherlands
13:53 - 14:16
The Gibbon Compiler: Accelerating a small subset of Haskell
Ryan R. NewtonIndiana University, Michael VollmerIndiana University, USA, Chaitanya KoparkarIndiana University
14:16 - 14:40
Copilot 3.0: a Haskell runtime verification framework for UAVs
Frank DeddenRoyal Netherlands Aerospace Center, Alwyn GoodloeNASA Langley Research Center, Ivan PerezNIA / NASA Formal Methods
14:40 - 15:00
Lightning talks Slot #2
15:20 - 16:30: GHCHIW at Elk
Chair(s): Brent YorgeyHendrix College
15:20 - 15:43
HoleFitPlugins and the future of interactive development in GHC
Matthías Páll GissurarsonChalmers University of Technology, Sweden
15:43 - 16:06
Explicit Dictionary Applications - From Theory to Practice?
Dominique DevrieseVrije Universiteit Brussel
File Attached
16:06 - 16:30
Visible dependent quantification
Ryan ScottIndiana University at Bloomington, USA
File Attached
16:50 - 18:00: CommunityHIW at Elk
16:50 - 16:52
Day closing
HiW'19 report
Niki VazouIMDEA Software Institute
16:52 - 17:15
GHC status report
Simon Peyton JonesMicrosoft, UK
17:15 - 18:00
Panel Discussion

Not scheduled yet

Not scheduled yet
Lightning talk: Simulate Bind with IxApplicative
Yuji YamamotoIIJ Innovation Institute, Japan

Call for Talks

The 11th Haskell Implementors’ Workshop is to be held alongside ICFP 2019 this year in Berlin. It is a forum for people involved in the design and development of Haskell implementations, tools, libraries, and supporting infrastructure, to share their work and discuss future directions and collaborations with others.

Talks and/or demos are proposed by submitting an abstract, and selected by a small program committee. There will be no published proceedings. The workshop will be informal and interactive, with open spaces in the timetable and room for ad-hoc discussion, demos and lightning talks.

Scope and Target Audience

It is important to distinguish the Haskell Implementors’ Workshop from the Haskell Symposium which is also co-located with ICFP 2019. The Haskell Symposium is for the publication of Haskell-related research. In contrast, the Haskell Implementors’ Workshop will have no proceedings – although we will aim to make talk videos, slides and presented data available with the consent of the speakers.

The Implementors’ Workshop is an ideal place to describe a Haskell extension, describe works-in-progress, demo a new Haskell-related tool, or even propose future lines of Haskell development. Members of the wider Haskell community encouraged to attend the workshop – we need your feedback to keep the Haskell ecosystem thriving. Students working with Haskell are specially encouraged to share their work.

The scope covers any of the following topics. There may be some topics that people feel we’ve missed, so by all means submit a proposal even if it doesn’t fit exactly into one of these buckets:

  • Compilation techniques
  • Language features and extensions
  • Type system implementation
  • Concurrency and parallelism: language design and implementation
  • Performance, optimization and benchmarking
  • Virtual machines and run-time systems
  • Libraries and tools for development or deployment


We invite proposals from potential speakers for talks and demonstrations. We are aiming for 20-minute talks with 5 minutes for questions and changeovers. We want to hear from people writing compilers, tools, or libraries, people with cool ideas for directions in which we should take the platform, proposals for new features to be implemented, and half-baked crazy ideas. Please submit a talk title and abstract of no more than 300 words.

Submissions can be made via HotCRP at https://icfp-hiw19.hotcrp.com/ until June 28th (anywhere on earth).

We will also have lightning talks session. These have been very well received in recent years, and we aim to increase the time available to them. Lightning talks be ~7mins and are scheduled on the day of the workshop. Suggested topics for lightning talks are to present a single idea, a work-in-progress project, a problem to intrigue and perplex Haskell implementors, or simply to ask for feedback and collaborators.

Invited Speakers

  • Lennart Augustsson & Satnam Singh

Program Committee

  • Jose Calderon (Galois, Inc)
  • Manuel Chakravarty (Tweag I/O & IOHK)
  • Jasper Van der Jeugt (Fugue)
  • Niki Vazou (IMDEA Software Institute)
  • Ningning Xie (The University of Hong King)
  • Brent Yorgey (Hendrix College)


Niki Vazou (niki.vazou@imdea.org)