Haskell Weekly


Issue 273 2021-07-22

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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.


  • What skills will give you an edge in 2022? (ad)

    Take the Developer Nation survey and share your views about the most important coding skills, tools, and platforms for 2022. You will get a virtual goody bag with free resources, plus a chance to win a new smartphone, a laptop, licenses, Amazon vouchers and more.

  • Kalvad - Dev + Ops Agency (ad)

    Kalvad is a Dubai based tech agency. We talk Python, Elixir and Haskell. Tell us about your scaling and monitoring problems.

  • Cheap interpreter, part 5: mea culpa by Gary Verhaegen

    While trying to write a faster version, I inadvertently discovered that all of my Haskell benchmarking was completely broken, so that will be the topic for this week.

  • Displaying Real-Time Data in Your Web Application Without Hassle: IHP Auto Refresh by Marc Scholten

    Ever wanted to display real-time data in your web application, but found WebSockets too much of a hassle? Add a single keyword in your IHP controller, and you are all set.

  • Hidden Identity: Using the Identity Monad by Monday Morning Haskell

    Last week, we looked at the “Function monad”. This week, we’re going to explore another monad that you might not think about as much. But even if we don’t specifically invoke it, this monad is actually present quite often, just in a hidden way!

  • Hspec Hooks by Matt Parsons

    The hspec testing library includes many useful facilities for writing tests, including a powerful “hooks” capability. These hooks allow you to provide data and capabilities to your tests.

  • Introducing Sandwich by Tom McLaughlin

    It’s been a little over a year since I made the first commit on a new test framework. But why write a new test framework? Working with existing frameworks, I found myself wanting several things.


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

In brief

  • Episode 0: Teaser by The Haskell Interlude

    We are starting a new Haskell-focused podcast where we interview guests from the Haskell community. The hosts are Niki Vazou, Joachim Breitner, Andres Löh, Alejandro Serrano and Wouter Swierstra. In this teaser episode, we introduce ourselves. The first regular episode will appear very soon.

  • LogicT empowered by Reflection without Remorse by Jason Dagit

    In the paper, sequences, such as sequences of binds are reified into type aligned sequences. This makes it cheap to inspect them without reassociating the binds. Thus getting rid of the quadratic slowdown incurred by inspecting the sequence. There is a downside in that the constant factors are worse.

  • Probability Tree Diagrams. Recursion Schemes. Why Finding the Right Solution is Sometimes Hard? by Robert Peszek

    The goal of this post is to present a simple example that uses recursion schemes. My other goal is to discuss my thoughts about reasons for getting stuck on finding the right solution. It will be a bit of a rant.

Show & tell

  • ad-delcont by Marco Zocca

    A Haskell implementation of the reverse AD framework presented in “Foundations for Efficient and Expressive Differentiable Programming”, available as a lightweight and easily extensible library.


    STORM is a Model-View-Controller style framework to build web applications. The framework lets you write expressive and auditable security policies with the data model. The policies are enforced via compile-time refinement type checking with LiquidHaskell.

  • Syphon by George Garrington

    A functional, minimalist MVU based language for creating Desktop GUI apps powered by Electron and React.

Call for participation