Haskell Weekly


Issue 133 2018-11-15

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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 very simple prime sieve in Haskell by Donnacha Oisín Kidney

    I’m going to try today to show a very simple prime sieve that (hopefully) rivals the simplicity of the definition above.

  • Announcing Validity version Validity of Double by Tom Sydney Kerckhove

    The Validity instance for Double has been highly controversial. The debate centers around whether NaN should be considered a valid value of type Double.

  • Existential quantification by Mark Karpov

    In this post I’m going to give an idea of how existentials can be useful in Haskell. I still remember the confusion that I felt when I first ran into rank-N types and the terms universal and existential quantification.

  • GTK+ programming with Haskell by Oskar Wickström

    As described on its webpage, GTK+, or the GIMP Toolkit, is a multi-platform toolkit for creating user interfaces. In this video we will use the haskell-gi suite of packages to build a simple GTK+ application with Haskell.

  • Introduction to state machine testing: Part 2 by Andrew McMiddlin

    In my first post on state machine testing I gave a high level view of what state machine testing is and some of the prerequisite knowledge. Now we’re going to start getting into the nuts and bolts of how state machine testing with hedgehog works.

  • REST-ish Services in Haskell: Part 2 by Vados

    Today we’re going to build castles in the sand — building up the domain of the solution we’re solving with as much help we can get from the formalisms in Haskell.

  • Thinking with Types: Type-Level Programming in Haskell by Sandy Maguire

    This book aims to be the comprehensive manual for type-level programming. It’s about getting you from a competent Haskell programmer to one who convinces the compiler to do their work for them.

  • Typed holes and valid hole fits by Matthías Páll Gissurarson

    In this post, I will try to explain typed-holes in the context of GHC, and some cool new contributions that were adopted by GHC that I proposed and implemented, namely, valid hole fits and refinement hole fits to make them even more useful for developers.


  • Senior back-end engineer at CentralApp in Brussels

    If you’re someone who likes functional programming, you get to work in Scala and Haskell in a fast-paced but perfectionist environment. We’re a small team and we’re growing fast, or at least that’s the plan. We strongly believe in investing in the team and building a culture that is product and engineering focused.

In brief

Package of the week

This week’s package of the week is Physics, a library for working with quantities in a performant and type-safe manner.

Call for participation