Haskell Weekly


Issue 100 2018-03-29

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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.

Want to see something featured in Haskell Weekly? Open an issue or pull request on GitHub.


  • Building blocks

    You may be wondering why am I using the phrase “building blocks”, it’s because, to me, this really feels like putting blocks together and sometimes dismantling them.

  • Three layer Haskell cake

    The question of “How do I design my application in Haskell?” comes up a lot. There’s a bunch of perspectives and choices, so it makes sense that it’s difficult to choose just one.

  • Generate type safe APIs with Fluid

    Fluid is a web API generator. It offers far more than type safety, and its goals aren’t limited to Haskell. First, let’s dive into a Hello World and see how it works.

  • The Task abstraction

    Neil Mitchell, Simon Peyton Jones and I have just finished a paper describing a systematic and executable framework for developing and comparing build systems. In this blog post I would like to share one interesting abstraction that we came up with to describe build tasks.

  • Applied category theory: Online course

    It just became a lot easier to learn about applied category theory, thanks to this free book. I think I’ll start a kind of informal online course or seminar based on this book on the Azimuth Forum.

  • The Maybe functor

    One of the simplest, and easiest to understand, functors is Maybe. It’s also sometimes known as the Maybe monad, but this is not a monad tutorial; it’s a functor tutorial. Maybe is many things; one of them is a functor.

  • Haskell lens: Part 1

    Lenses are one of the most popular, yet confusing aspect of Haskell. To be fair, I could never really understand how they work. This series of posts is going to be my attempt to understand lenses, the ideas and implementation details, and also the lens package.

  • Everyday Haskell

    Up to this point, we’ve been covering a subset of the Haskell language which would look unusual to an experienced Haskell programmer. In our quest to make side-effects, we’ve skipped over a lot of useful functionality which makes programming in Haskell more pleasant.

  • An old and a new library for generic deriving

    In this post, I want to talk about how it takes advantage of existing infrastructure in the GHC.Generics module to condense some of these generic implementations to one-liners.

  • sv: Introduction, status, and road map

    sv is QFPL’s new CSV library for Haskell. The core data structure of sv is a syntax tree for CSV that preserves white-space, quoting information, newline style, and other data that is usually thrown away.


  • Software engineer at Capital Match in Singapore

    Our platform, built almost entirely from Haskell, is the largest marketplace invoice financing platform in South-East Asia, having processed more than US$50 million in funding over the past two years. We’re currently expanding into new markets and new territories, and we’re looking to expand our team!

  • Software engineer at Tweag I/O

    We have found functional programming in particular to be an enabling factor for us on some of the most ambitious projects we’ve faced for our clients: breaking through the exascale barrier in HPC, modeling a large variety of physiological processes in the human body, designing pipelines for storing and analyzing biophysical data, video search with natural language, building complex SaaS products with thousands of concurrent users and many others.

  • Haskell expert at Well-Typed

    We are looking for a Haskell expert to join our team at Well-Typed. This is a great opportunity for someone who is passionate about Haskell and who is keen to improve and promote Haskell in a professional context.

  • Software developer at Obsidian Systems in New York City

    Obsidian Systems is looking for developers to work on full-stack Haskell web and mobile applications. We’re an 18-person team with a wide range of clients including seed-stage startups, multinational corporations, universities, and research groups. We provide innovative and robust technical solutions in support of our clients’ unique goals and challenges.

In brief

Package of the week

This week’s package of the week is Herm’s, a command-line manager for delicious kitchen recipes.

Call for participation