Haskell Weekly


Issue 129 2018-10-18

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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.


  • GHC 8.4.4 released

    The GHC team is pleased to announce the availability of GHC 8.4.4, a patch-level release in the 8.4 series. This release fixes several bugs present in 8.4.3.

  • Aelve Guide: Alpha version released

    Today we’re releasing the first version of Aelve Guide — an informal wiki for the Haskell ecosystem and community. It’s written in Haskell, too.

  • Haskell’s kind system: A primer

    In this post we’ll explore Haskell’s kind system, the similarities between types and kinds, and show how these can be leveraged to write safer and more reusable code.

  • A JavaScript wat and monoidal folds

    We suppose all programming languages have the occasional wat, some function or behavior that is surprising and makes you think, “wait, what?”

  • An applicative password list

    How to use the applicative functor capabilities of lists to create a password list, with examples that object-oriented programmers can understand.

  • Fixpoints in Haskell

    If you have a function from any set to itself, then a fixpoint of that function is any input that maps to itself.

  • Haskell by day

    I have always thought Haskell is this far-out, esoteric, academic language that no one uses.

  • How to test Servant applications

    In this recipe we’ll work through some common testing strategies and provide examples of utilizing these testing strategies in order to test Servant applications.

  • Practical Haskell programs from scratch: A quick and easy guide

    Here, I will supply what I consider to be the fastest way to get up and running with Haskell — it’s opinionated, and I’m sure you’ll want to tweak and improve on it as you learn more.

  • Subvert your type checker today!

    Do you wish you could do IO from any monad transformer stack, including those stacks that do not have IO at the base?


In brief

Package of the week

This week’s package of the week is Pipes, a clean and powerful stream processing library that lets you build and connect reusable streaming components.

Call for participation

Looking to participate in the fifth annual Hacktoberfest? Check out some of these issues with the “Hacktoberfest” label from Haskell repositories on GitHub!