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Andres Löh

@kosmikus.bsky.social

1K followers 123 following 31 posts

Partner and Haskell Consultant at Well-Typed LLP. Board member of the Haskell Foundation. Co-host of the Haskell Interlude and the Haskell Unfolder. Posts mostly about Haskell, and occasionally about books, video games, and other things that interest me.

Posts Replies Media

Reposted by Andres Löh

Haskell Interlude @haskellinterlude.bsky.social · 27/04/2026

We sat down with Torsten Grust who is a professor of DB systems at the University of Tübingen. We talked about the best way to program databases, how to bridge the gap between regular programming languages and databases, and compiling just about everything to SQL. haskell.foundation/podcast/81/

haskell.foundation

Mike and Andres sat down with Torsten Grust, who is a professor of DB systems at the University of Tübingen. Even though Torsten loves SQL, he's used functional programming and Haskell to inform his w...

Andres Löh @kosmikus.bsky.social · 21/04/2026

After a somewhat longer break, we're finally back with a new #Haskell #Unfolder episode. Tomorrow, 2026-04-22, at 18:30 UTC, Edsko and I will talk about selective applicative functors. www.youtube.com/watch?v=Yt2E...

Not quite monads (Haskell Unfolder #54)

YouTube video by Well-Typed

Reposted by Andres Löh

BOB Konferenz @bobkonf.de · 12/03/2026

The final tutorial on track A at #BOBkonf2026 is @kosmikus.bsky.social 's "Haskell Tutorial", an introduction to Haskell. Find out more: bobkonf.de/2026/loeh.html

Andres Löh @kosmikus.bsky.social · 21/01/2026

Join us tonight, 2026-01-21 at 1930 UTC, for the first new #Haskell #Unfolder episode of 2026, on static pointers. www.youtube.com/watch?v=Mc3l...

Static pointers (Haskell Unfolder #53)

"Static pointers" are references to statically known values, and can serialized independent of the type of the value (even if that value is a function), so that you can store them in files, send them ...

Andres Löh @kosmikus.bsky.social · 10/12/2025

Join us for a new episode of the #Haskell #Unfolder, today, 2025-12-10 at 1930 UTC. This time we're discussing bidirectional parsing and printing, using as an example the autodocodec package. www.youtube.com/watch?v=z9V5...

Bidirectional parsing and printing (of JSON) (Haskell Unfolder #52)

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 12/11/2025

There's going to be a new episode of the #Haskell #Unfolder today, 2025-11-12, at 1930 UTC. We're going to discuss how to implement (more) type-safe APIs via some type-level programming using the sop-core package. www.youtube.com/watch?v=3XeI...

Typed servers using sop-core (Haskell Unfolder #51)

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 29/10/2025

Join us tonight for the 50th (!) episode of the #Haskell #Unfolder, on singletons! Live on YouTube 1930 UTC (note the changed time in some countries due to DST-related fluctuations). www.youtube.com/watch?v=-zxx...

Singletons (Haskell Unfolder #50)

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 15/10/2025

Join us today, 2025-10-15, at 1830 UTC, for a new episode of the #Haskell #Unfolder, on the importance of shrinking for property-based testing: www.youtube.com/watch?v=EcV4...

Shrinking (Haskell Unfolder #49)

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 01/10/2025

After a long summer break, we're finally back for a new episode of the #Haskell #Unfolder: Edsko and I are going to talk about safe coercions, newtype vs data, roles and more ... Today, 2025-10-01, 1830 UTC on YouTube: www.youtube.com/watch?v=NC0w...

Safe coercions (Haskell Unfolder #48)

YouTube video by Well-Typed

Reposted by Andres Löh

TNG Technology Consulting GmbH @tngtech.com · 04/08/2025

We have confirmed three keynotes for MuniHac 2025. Join us in Munich between September 12th and 14th for talks by Andrew Lelechenko, @sperbsen.bsky.social, and Rodrigo Mesquita as well as workshops and hacking projects: munihac.de/2025.html#re... #MuniHac #Haskell

Andres Löh @kosmikus.bsky.social · 23/07/2025

Join us today, 2025-07-23, 1830 UTC, live on YouTube for a new episode of the #Haskell #Unfolder, this time on "pure parallelism". www.youtube.com/watch?v=trDq...

Pure parallelism (Haskell Unfolder #47)

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 09/07/2025

Today, Wednesday, 2025-07-09, at 1830 UTC, there's going to be a new episode of the #Haskell #Unfolder. Edsko and I will show how to develop a small but useful Haskell CLI application completely from scratch. www.youtube.com/watch?v=5W0Z...

Developing an application from scratch (Haskell Unfolder #46)

YouTube video by Well-Typed

Reposted by Andres Löh

Haskell programming language @haskell.org · 07/07/2025

Better infrastructure, fewer surprises. We’re raising $6K for a dedicated ARM server to support #Haskell’s infrastructure (CI, backups, etc). Let’s build infra you can rely on! Every contribution helps! Donate: donorbox.org/infrastructu... Read more: discourse.haskell.org/t/infrastruc...

Infrastructure Independence | Haskell.org, Inc (Powered by Donorbox)

Historically, the Haskell community has relied on a mix of cloud providers and self-hosted servers for our core infrastructure (Hackage, Stackage, GHC, CI, etc.). More recently the Haskell Infrastruct...

Reposted by Andres Löh

Manuel Chakravarty @tacticalgrace.justtesting.org · 06/07/2025

Well, unless we do something about it.

Andres Löh @kosmikus.bsky.social · 24/06/2025

On Wednesday, 2025-06-25, at 1830 UTC, there will be a new episode of the #Haskell #Unfolder. This time, Edsko and I will discuss the current situation of records in Haskell. www.youtube.com/watch?v=9hrD...

Haskell records in 2025 (Haskell Unfolder #45)

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 14/05/2025

If you want to hear from Edsko and me how to test stateful APIs using quickcheck(-lockstep), join us today, 2025-05-14, at 1830 UTC, live on YouTube for a new episode of the #Haskell #Unfolder: www.youtube.com/watch?v=RPQV...

State-based testing with quickcheck-lockstep (Haskell Unfolder #44)

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 07/05/2025

Today, there will be a new #Haskell #Unfolder episode, where Edsko and I will talk about the monomorphism restriction and defaulting. Join us live on YouTube 2025-05-07 at 1830 UTC (or watch later) via www.youtube.com/watch?v=nD93...

The Haskell Unfolder Episode 43: monomorphism restriction and defaulting

YouTube video by Well-Typed

Reposted by Andres Löh

BOB Konferenz @bobkonf.de · 07/05/2025

The video of @kosmikus.bsky.social's #BOBkon2025 talk "Abstraction and program design, or the power of parametricity" is now up! bobkonf.de/2025/loeh.html

BOB - Abstraction and program design, or the power of parametricity

BOB Konferenz, Best of Breed Konferenz für Software-Entwickler und Entscheider in der Softwareentwicklung.

Andres Löh @kosmikus.bsky.social · 15/04/2025

The #Haskell #Unfolder is two years old! Join us for a new episode tomorrow, 2025-04-16, at 1830 UTC, live on YouTube. This time, the topic is logic programming with typedKanren, which is a typed version of #miniKanren embedded into Haskell. www.youtube.com/watch?v=ukk5...

The Haskell Unfolder Episode 42: logic programming with typedKanren

YouTube video by Well-Typed

Reposted by Andres Löh

Simon Marlow @simonmar.bsky.social · 28/03/2025

I'm thinking about a second edition of Parallel and Concurrent Programming in Haskell. Any thoughts on what should be added (or removed)? What's missing, what updates are needed to reflect common usage? The obvious new things are async and Haxl. Should the chapter on distributed-process be kept?

Andres Löh @kosmikus.bsky.social · 26/03/2025

Tonight, 2025-03-26, at 1930 UTC (still an unusual time for US/Canada) there'll be a new episode of the #Haskell #Unfolder, and after all this time, we'll finally talk about generics! www.youtube.com/watch?v=db-K...

The Haskell Unfolder Episode 41: generic monoids

YouTube video by Well-Typed

Reposted by Andres Löh

Satnam Singh @satnam6502.bsky.social · 21/03/2025

Please consider submitting to FUNARCH 2025, a workshop that is part of the @icfp-conference.bsky.social week in Singapore this October. At the intersection of software engineering and functional programming, bsky.app/profile/funa... conf.researchr.org/home/icfp-sp...

conf.researchr.org

FUNARCH 2025 - ICFP/SPLASH 2025

The Third ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large “Functional Software Architecture” refers to methods of construction and structure of large and long-lived softwar...

Reposted by Andres Löh

Active Group GmbH @active-group.de · 18/03/2025

Unser C*O @sperbsen.bsky.social und @kosmikus.bsky.social haben gemeinsam die neuste Folge des Podcasts der Haskell Foundation (Haskell Interlude) moderiert: ein Gespräch mit Farhad Mehta, Professor für Informatik (OST Rapperswil) & @zurihac.bsky.social-Organisator. haskell.foundation/podcast/63/

Andres Löh @kosmikus.bsky.social · 11/03/2025

Tomorrow, 2025-03-12, at 1930 UTC (note: one hour later than usual in Canada / US due to asynchronous DST shifts), there'll be a new episode of the #Haskell #Unfolder, titled "understanding through a model". We'll talk about QuickCheck and convolutions ... www.youtube.com/watch?v=0QTt...

The Haskell Unfolder Episode 40: understanding through a model

YouTube video by Well-Typed

Reposted by Andres Löh

BOB Konferenz @bobkonf.de · 28/02/2025

#BOBkonf2025 is two weeks away, and we only have very few tickets left -- the location will let us bump the numbers until Monday, so get your ticket now if you haven't already! bobkonf.de/2025/registr...

Andres Löh @kosmikus.bsky.social · 25/02/2025

Please consider nominating yourself to be a member of the Board of the #Haskell Foundation: discourse.haskell.org/t/2025-call-...

discourse.haskell.org

2025 Call for nominations for the Haskell Foundation

Hello! everyone The Haskell Foundation’s directors are pleased to announce the nomination process for seats on the Foundation’s board of directors. The board is the ultimate decision-making body of ...

Andres Löh @kosmikus.bsky.social · 11/02/2025

Tomorrow, 2025-02-11, we'll live-stream a new episode of the #Haskell #Unfolder. Edsko and I will discuss the various strategies for deriving instances that GHC offers and their relative strengths and weaknesses. Hope to see you all there! www.youtube.com/watch?v=NEUb...

The Haskell Unfolder Episode 39: deriving strategies

YouTube video by Well-Typed

Reposted by Andres Löh

BOB Konferenz @bobkonf.de · 22/01/2025

@kosmikus.bsky.social will be at #BOBkonf2025 with "Abstraction and program design, or the power of parametricity": bobkonf.de/2025/loeh.html

Andres Löh @kosmikus.bsky.social · 14/01/2025

The #Haskell #Unfolder is back! In tomorrow's episode, we'll take a look at #CUDA and write some simple functions in it. We'll also show how to interface from Haskell to CUDA and how to use QuickCheck to test CUDA functions from Haskell. www.youtube.com/watch?v=ww4C...

The Haskell Unfolder Episode 38: tasting and testing CUDA (map, fold, scan)

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 03/12/2024

Tomorrow, 2024-12-04, at 1930 UTC, there'll be a new episode of the #Haskell #Unfolder live on YouTube. This time, we'll try to solve Day 4 of #AdventOfCode 2024. www.youtube.com/watch?v=KkKx...

The Haskell Unfolder Episode 37: solving Advent of Code 2024 day 4

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 19/11/2024

Tomorrow, 2024-11-20, at 1930 UTC, there'll be a new episode of the #Haskell #Unfolder, on concurrency and the FFI. Edsko will explain to me what exactly the difference is between "safe" and "unsafe" FFI calls and whether safe calls are actually safe ... www.youtube.com/watch?v=IMrB...

The Haskell Unfolder Episode 36: concurrency and the FFI

YouTube video by Well-Typed

Reposted by Andres Löh

JMCT @jmct.bsky.social · 18/11/2024

Is it cool if I post one of my favorite creations from the other place? #functionalprogramming #math #programming

Andres Löh @kosmikus.bsky.social · 05/11/2024

Tomorrow, 2024-11-06, at 1930 UTC, Edsko and I will stream a new episode of the #Haskell #Unfolder. This time, we're going to look at two type classes in the Haskell world that are perhaps less widely known: Distributive and Representable. Join us live on YouTube: www.youtube.com/watch?v=g_vK...

The Haskell Unfolder Episode 35: distributive and representable functors

YouTube video by Well-Typed

Andres Löh @kosmikus.bsky.social · 05/11/2024

The latest episode of the #Haskell #Interlude brings back many fond memories. Our guest Gabriele Keller is professor at Utrecht University, where I did my PhD long ago. Joachim, Gabriele and I talk about Gabriele's Haskell journey that took her all around the planet. haskell.foundation/podcast/57/

haskell.foundation

Gabriele Keller

Gabriele Keller, professor at Utrecht University, is interviewed by Andres and Joachim. We follow her journey through the world as well as programming languages, learn why Haskell is the best environm...

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Reposted by Andres Löh

Manuel Chakravarty @tacticalgrace.justtesting.org · 22/10/2024

The next Haskell Utrecht Meetup is on 18 November. Check it out! www.meetup.com/haskell-utre...

Haskell Utrecht Meetup, Mon, Nov 18, 2024, 7:30 PM | Meetup

Mark your calendars: the next Haskell Utrecht Meetup will be on November 18th. We will be back in the University Library - room 0.21 - in the City Center. Note that you ca

Andres Löh @kosmikus.bsky.social · 30/04/2024

The #Haskell #Unfolder is now 1 year old! In the anniversary episode, Edsko and I will return to the very first topic and consider (un)folds, but now in a more generic setting. Live on YouTube 2024-05-01 at 1830 UTC. www.youtube.com/watch?v=QTgR...

The Haskell Unfolder Episode 24: generic (un)folds

In our first anniversary episode, we are connecting back to the very beginning of the Haskell Unfolder and talk about unfolds and folds. But this time, not o...

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Andres Löh @kosmikus.bsky.social · 09/04/2024

At Well-Typed, we are currently looking for a new #Haskell developer (possibly more) to join our team: well-typed.com/blog/2024/04...

Reposted by Andres Löh

Active Group GmbH @active-group.de · 09/04/2024

Nächste Woche Donnerstag - am 18. April - veranstalten wir einen großen Online-Tutorial-Tag zur funktionalen Programmierung, mit Workshops zu diversen FP-Sprachen, DDD, Isabelle, funktionalen UIs uvm. und einem AMA zum Schluss - für symbolische 10€. funktionale-programmierung.de/2024/04/09/t...

funktionale-programmierung.de

Funktionale Programmierung - Tutorialtag: einen Tag voll funktionaler Programmierung mit der Active Group

Andres Löh @kosmikus.bsky.social · 20/03/2024

We will stream a new episode of the #Haskell Unfolder today, on "foldr-build fusion", an optimisation the Haskell compiler applies to improve pipelines of list-processing functions. Join us live on YouTube, 2024-03-20 at 1930 UTC, or watch the recording afterwards: www.youtube.com/watch?v=C-Ga...

The Haskell Unfolder Episode 22: foldr-build fusion

When composing several list-processing functions, GHC employs an optimisation called foldr-build fusion. Fusion combines functions in such a way that any int...

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Reposted by Andres Löh

BOB Konferenz @bobkonf.de · 05/03/2024

In "Staging Programs in Haskell", @kosmikus.bsky.social's #BOBkonf2024 tutorial, we'll learn what staging is, why and how it is useful, and how to implement it in Haskell. More information: bobkonf.de/2024/loeh.html

Reposted by Andres Löh

BOB Konferenz @bobkonf.de · 01/03/2024

@tacticalgrace.bsky.social's #BOBkonf2024 talk "Functional Programming in Swift" lays out how Swift holds its own as a modern multi-paradigm language: bobkonf.de/2024/chakrav...

Reposted by Andres Löh

Linotype Pilgrim @symbo1ics.bsky.social · 21/02/2024

This is actually very good for #Haskell learners - live now www.youtube.com/watch?v=WHVM... #WellTyped Dijkstra's shortest path Haskell Unfolder

The Haskell Unfolder Episode 20: Dijkstra's shortest paths

In this (beginner-friendly) episode, we will use Dijkstra's shortest paths algorithm as an example of how one can go about implementing an algorithm given in...

Reposted by Andres Löh

José A. Alonso @jalonso.eurosky.social · 22/02/2024

The Haskell Unfolder Episode 20: Dijkstra's shortest paths. ~ Edsko de Vries (@EdskoDeVries), Andres Löh (@kosmikus@functional.cafe). www.youtube.com/live/WHVMjMI... #Haskell #FunctionalProgramming

Reposted by Andres Löh

Manuel Chakravarty @tacticalgrace.justtesting.org · 05/02/2024

The next Haskell Utrecht Meetup is on 23 April and we will have Niki Vazou and Simon Peyton Jones as speakers. The meetup will be at the offices of Channable who we like to thank for their support! www.meetup.com/haskell-utre...

Haskell Utrecht Meetup, Tue, Apr 23, 2024, 7:00 PM | Meetup

The next Haskell Utrecht Meetup will be on April 23rd. We will be in at the Channable office again -- mark your calendars because this is one Meetup that you won't want to

Andres Löh @kosmikus.bsky.social · 05/12/2023

Tomorrow, 2023-12-06, there'll be a new episode of the #Haskell Unfolder. We'll dive into Haskell's history and discuss the somewhat controversial "Applicative Monad Proposal" from 2015. We'll use it as an example to demonstrate the power of the DerivingVia extension. www.youtube.com/watch?v=tnCH...

The Haskell Unfolder Episode 16: monads and deriving via

In this episode, we'll see how deriving-via can be used to capture rules that relate type classes to each other. As a specific example, we will discuss the d...

Andres Löh @kosmikus.bsky.social · 21/11/2023

New episode of the #Haskell Unfolder upcoming. Tomorrow, 2023-11-22, at 1930 UTC, Edsko and I will discuss interruptible operations, a topic that was requested by our audience during the episode we did on generalBracket. www.youtube.com/watch?v=VpYC...

The Haskell Unfolder Episode 15: interruptible operations

In episode 10 on generalBracket we discussed asynchronous exceptions: exceptions that can be thrown to a thread at any point. In that episode we saw that co...

Reposted by Andres Löh

Manuel Chakravarty @tacticalgrace.justtesting.org · 17/11/2023

Heads up! The next Haskell Utrecht Meetup is going to be on 11 December: www.meetup.com/haskell-utre...

Haskell Utrecht Meetup, Mon, Dec 11, 2023, 7:00 PM | Meetup

Mark your calendars: the next Haskell Utrecht Meetup will be on December 11th. We will be in a new location - room 0.21 in the *Universiteitsbibliotheek* (University Libra

Reposted by Andres Löh

José A. Alonso @jalonso.eurosky.social · 09/11/2023

The Haskell Unfolder Episode 14: Higher-kinded types. ~ Edsko de Vries (@EdskoDeVries), Andres Löh (@kosmikus). www.youtube.com/live/EXgsXy1... #Haskell #FunctionalProgramming

Reposted by Andres Löh

BOB Konferenz @bobkonf.de · 25/10/2023

#BOBkonf2024 is thrilled to announce its first sponsor, Well-Typed LLP (well-typed.com)! Thank you for your continued support as a Bronze level sponsor.