Haskell Weekly


Issue 207 2020-04-16

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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.


  • Why Haskell Matters by Thomas Mahler

    In this article I try to explain why Haskell keeps being such an important language by presenting some of its most important and distinguishing features and detailing them with working code examples.

  • Micro C, Part 1 by Joseph Morag

    Welcome to the beginning of the compiler proper!

  • Polymorphic Perplexion by Ranjit Jhala

    Thanks to its ubiquity, we often take polymorphism for granted, and it can be quite baffling to figure out why verification fails with monomorphic signatures.

  • Rewriting to Haskell: Testing by Riccardo Odone

    We have managed to delay testing by leaning on Ruby RSpec for a while. It’s time to do the right thing and write some tests in Haskell.

  • Servant Testing Helpers! by Monday Morning Haskell

    This week, we’re going to look at a couple shortcuts we can take that will make testing our server a little easier.

  • Streaming the Redis replication stream by Wander Hillen

    In this post I’ll implement this simpler way and also show off a nicer way to initialize the replication stream with PSYNC that does not rely on pulling in the entire redis contents first.

  • Things Software Engineers Trip Up On When Learning Haskell by William Yaoh

    Most likely you’ve worked in an imperative language, and now you want to find out what all the fuss about functional programming is.

  • The three kinds of Haskell exceptions and how to use them by Arnaud Spiwack

    In this blog post, I’d like to explain how I recommend understanding and using Haskell’s exceptions.

  • Towards Faster Iteration in Industrial Haskell by Patrick Thomson

    This particular post concerns one industry perspective: the speed at which a team of programmers can iteratively improve and extend a given codebase.

  • The Vitality of Haskell by Chris Dornan

    Strong types have allowed even the base package on which everything is generally based to evolve continuously.


  • Interos is Hiring Full Stack Haskell Software Engineers (ad)

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In brief

  • Building a reproducible blog with Nix by Yannik Sander

    Nix is a purely functional package manger that allows isolated development environments and builds.

  • Initial Algebra as Directed Colimit by Bartosz Milewski

    In this series of blog posts I will explore the ways one can construct these (co-)algebras using category theory and illustrate it with Haskell examples.

  • Lesson 7: The Compose newtype by Type Classes

    This lesson will extend the theme of the previous lesson, picking up where it left off and then introducing another newtype called Compose that generalizes this idea that any two functors or applicative functors can, well, compose.

  • Performance comparison of parallel ray tracing in functional programming languages by Troels Henriksen

    The intent is to investigate, on a rather small and simple problem, to which degree functional programming lives up to the frequent promise of easy parallelism, and whether the resulting code is actually fast in an objective sense.

  • Programming totally with head and tail by Li-yao Xia

    Today, we will investigate a more exotic answer using dependent types.

  • A Type-Safe Approach to Categorized Data by Eli Peery

    In this post we’ll go over one technique for representing categorized data in a way that prevents us from making careless errors and brings us some peace of mind.

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