Haskell Weekly


Issue 152 2019-03-28

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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.


  • The minimalist prelude

    Implementing the 73rd alternate Prelude seems to have become a favorite pastime of many Haskellers right after they finished writing their Monad tutorial as the traditional rite of passage. However, I’d like to explore the opposite side of the spectrum: Why not try being minimalist? I mean, it’s the least we can do!

  • GSoC 2019 Student Applications now open by Jasper Van der Jeugt

    We’d like to remind you that Google has opened student applications for Google Summer of Code 2019.

  • Comonadic builders by Dmitrii Kovanikov

    Turns out, you actually can use comonads to solve production problems from the real world.

  • Flag, a tagged Bool by Oleg Grenrus

    This posts complements two other recent blogs: Code smell: Boolean blindness by Thomas Tuegel and Ceci n’est pas un default by Guillaume Allais.

  • Higher-rank types in Standard Haskell by Li-yao Xia

    I got to think about this puzzle: how to write higher-rank polymorphic functions, without using RankNTypes or any other language extension?

  • Property-Based Testing in a Screencast Editor, Case Study 1: Timeline Flattening by Oskar Wickström

    This post is the first case study in the series, covering the timeline flattening process in Komposition and how it’s tested using PBT.

  • Recursion Schemes: the high-school introduction by Christophe Calvès

    All you need, to see what recursion schemes are and why there are useful, can be presented with just a single basic function, often taught as an introduction to programming: factorial.

  • Return a Function to Avoid Effects by Matt Parsons

    To help write robust, reliable, and easy-to-test software, I always recommend purifying your code of effects. There are a bunch of tricks and techniques to accomplish this sort of thing, and I’m going to share one of my favorites.

  • Structuring your first Haskell project with Stack by Saksham Sharma

    If you read such blogs, you would have been told that ghci is your best friend. This article will attempt to change that.

  • Study into exact real arithmetic Pt. 2 by Henri Tuhola

    For now it’s sufficient to understand that the library can compute exactly something such as sin(1.4*π) + log(5).


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In brief

Package of the week

This week’s package of the week is scheduler, a work stealing scheduler, which is very useful for tasks parallelization.

Call for participation