Haskell Weekly


Issue 276 2021-08-12

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Welcome to another issue of Haskell Weekly! Haskell is a safe, purely functional programming language with a fast, concurrent runtime. This is a weekly summary of what’s going on in its community.


  • A Brief Intro to Monad Transformers by Solomon Bothwell

    A few friends have recently asked about literature introducing Monad Transformers. The best introduction I have found was in Haskell Programming From First Principles. If you don’t have, or want to purchase, this book, then here is a brief explanation with examples.

  • A brief intro to MTL by Jappie Klooster

    That blogpost inspired me to write this, because I can’t find a succinct description on how to use MTL. I learned MTL by staring at reflex for days, if not weeks.

  • Cast Values with Witch by Haskell Weekly Podcast

    Back from summer break, Cameron Gera discusses the Witch library with it’s author, Taylor Fausak. Learn about the many motivations behind this simple library for converting values between various types.

  • Cheap interpreter, part 8: faster register machines by Gary Verhaegen

    In this post, I’ll show a few tricks that can be used to make this example quite a bit faster.

  • Counting Cardinalities by Mitchell Vitez

    One important piece of information about a type is how many possible values it contains. Let’s examine some ways to compute that info.

  • Episode 1: Emily Pillmore by The Haskell Interlude

    The guest of our first regular episode is Emily Pillmore, CTO of the Haskell Foundation. The hosts are Alejandro Serrano and Andres Löh. We talk about Emily’s path to Haskell, the role of the Haskell Foundation and the CTO within the Haskell Foundation, about current projects, the Haskell Community and about Emily’s work on Optics.

  • GHC activities report: June–July 2021 by Well-Typed

    This seventh edition of our GHC activities report marks the one-year anniversary since that start of sending out these regular updates on the work on GHC and related projects that we are doing at Well-Typed.

  • Writing a (toy) symbolic interpreter, and solving challenges, part 4 by Simon Marechal

    Hopefully, if you have followed so far, you now have a good idea of what writing a simple symbolic execution engine entails. This means that you can either try to write your own, or that you should be comfortable using something a little more battle tested.


Trying to hire a Haskell developer? You should advertise with us!

In brief

  • Solving a few Leetcode questions in Haskell by Micah Cantor

    One of the difficulties with solving Leetcode questions with a functional langauge like Haskell is that most, if not all, solutions and explanations for a given question are presented in an imperative or object-oriented style.

  • State of the Core Libraries Committee by Emily Pillmore

    The Core Libraries Committee is undergoing some changes at the moment, and I’d like to fill everyone in about the state of the CLC, what’s happening behind the scenes, and what we hope to accomplish in the future.

Show & tell

  • Cabal version 3.6 by Emily Pillmore

    This is the fourth release of the 3.0 release series, and highlights include support for GHC 9.2, as well as many new code quality improvements + organization work on the repo itself.

  • IHP version 0.13 by Marc Scholten

  • jet-stream by Daniel Diaz Carrete

    This is a streaming library focused on simplicity at the cost of some expressivity.

  • Kind

    Kind is a functional, general-purpose programming language featuring theorems and proofs. It has the smallest core, a pretty solid JavaScript and Scheme compiler, and a syntax that is a middle ground between Haskell and TypeScript, in an attempt to make it more accessible.

  • Monomer by Francisco Vallarino

    An easy to use, cross platform, GUI library for writing native Haskell applications.

  • text version 1.2.5 by Andrew Lelechenko

    On behalf of the maintainers team I’m happy to announce that text- is released. It is to be shipped with the upcoming GHC 9.2.

Call for participation