Haskell Weekly


Issue 241 2020-12-10

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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.


  • Developer Economics Survey (ad)

    It’s our 20th survey anniversary! Discover new questions, prizes, and surprise perks.

  • Advent of Haskell by Armando Santos

    Denotational Design, developed by Conal Elliott, is an abstract and rigorous design method, that forces the programmer to really understand the nature of his problem domain, stepping back and design the meaning of abstraction before implementing it.

  • Building a Bulletin Board Using Scotty and Friends by Gil Mizrahi

    It’ll be so simple that we won’t even use a database, but hopefully it’ll provide enough information on scotty that you can continue it yourselves if you’d like.

  • Capturing the magic of Prelude.interact by Samuel Gélineau

    The purpose of this post is to encourage you to consider the pure framework style more often.

  • Haskell documentation with Haddock: Wishes’n’tips by Veronika Romashkina & Dmitrii Kovanikov

    The blog post is going to give Haddock overview, suggest documentation best practices, reveal the specialities of the Haddock tool, and show-and-tell lots of different examples of how to squeeze more out of your documentation.

  • Haskell: The Bad Parts, part 3 by Michael Snoyman

    Note that this is the last blog post in this series where I had specific ideas queued up. So it’s likely that this will be the last post for a while until I get annoyed by something again.

  • Parser Combinators: a Walkthrough by Antoine Leblanc

    Today, I want to explore Parsec, and most specifically how Parsec works. Parsing is ubiquitous, and most Haskell programs will use Parsec or one of its variants.

  • Processing CodeBlocks in Hakyll by Mario Lang

    In this article, we will cover Pandoc as it is used in the Hakyll static site generator.

  • Santa’s Little Lua Scripts by Albert Krewinkel

    Santa would just need to expose the relevant parts of the Haskell system, so the Elves could access and script it as their hearts desired.

  • The shrinks applicative by Arnaud Spiwack

    The shrinker turns the output of a failed property test from “your function has a bug” to “here is a small actionable example where your function fails to meet the specification”.

  • Whirlwind Tour Of Stack For Beginners by School of FP

    In this post, we will take a look at stack. It is the 3rd in a series of posts about getting started with Haskell.


  • Executive Directory of the Haskell Foundation

    HF seeks a full-time Executive Director (ED) to lead and develop the organization going forward. The ED is responsible for furthering the HF’s mission and vision, ensuring that resources are in place to accomplish its goals.

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

In brief

  • Adding Hints by Monday Morning Haskell

    In this week’s video, we’ll see how to add “hints” to the Watcher. This way, a user can get a little extra help when they need it!

  • DAML: A Haskell-Based Language for Blockchain by Gints Dreimanis

    In the interview, we talk about DAML, the benefits and downsides of functional programming languages, and their practical experience while building DAML.

  • Exaggerating the negatives by Chris Martin

    Cussing is not the problem; hyperbolic non-communication is the problem. Grievances or laments about the “garbage fire” are heavy. Not light

  • The Halting Problem (Part 1) by Callan McGill

    We will first prove halting for the lambda calculus and then see how the same argument looks when transplanted to Haskell.

  • Knowledge-as-Code by Mikael Tönnberg

    When programming, we want to capture knowledge in a way understandable for both the computer and humans, now and in the future.

Show & tell

  • Brittany version by Taylor Fausak

    Added support for GHC 8.10 and dropped support for 8.4, 8.2, and 8.0.

  • group-theory by Emily Pillmore

    This package includes definitions for Groups (monoids with invertibility), including finite, free, simple, cyclic, and permutation groups.

  • numhask-free by Tony Day

    The Free Num is a Sequence of Bags.

  • password by Felix Paulusma

    A library providing functionality for working with plain-text and hashed passwords with different types of algorithms.

Call for participation