Haskell Weekly


Issue 232 2020-10-08

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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.


  • Collect in Rust, traverse in Haskell and Scala by Michael Snoyman

    There’s a running joke in the functional programming community. Any Scala program can be written by combining the traverse function the correct number of times. This blog post is dedicated to that joke.

  • Experiences after installing Haskell language server by Henri Tuhola

    The Haskell language server is definitely making programming more smooth by reducing roundtrips outside to the terminal or the browser.

  • Let’s build a Cloudflare Worker with WebAssembly and Haskell by Cristhian Motoche

    In exploring the tools that help us run our systems based on Haskell, our developer Cristhian Motoche has created a tutorial that shows how to compile Haskell to WebAssembly using Asterius for deployment on Cloudflare.

  • Making GHCIDE smarter and faster: a fellowship summary by Zubin Duggal

    The product of this fellowship was a good selection of ghcide and haskell-language-server features that you can use right now, or will be able to use very soon, including better search, richer information and more efficient queries.

  • Production Haskell Alpha Release by Matt Parsons

    I’m thrilled to announce that my book Production Haskell is released in alpha version. The first release has 240 pages of content, with much much more to come.

  • Starting Haskellings! by Monday Morning Haskell

    In this week’s video blog, we’ll learn a little bit about using the ghc command on its own outside of Stack/Cabal, and then how to run it from within our program using the System.Process library.

  • Substitution and Equational Reasoning by Gil Mizrahi

    In a lazy functional language where variables are immutable and effects are explicit, new powerful tools for understanding what programs mean become available - substitution and equational reasoning.


  • Backend Engineer at Freckle

    We are seeking an experienced, talented Backend Engineer to join the engineering team at Freckle by Renaissance. You’ll be bringing your talents and expertise to continue building and evolving our highly available and distributed SaaS platform.

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

In brief

  • Game :: Dangerous update by Steven Tinsley

    A while ago I posted here about Game :: Dangerous, which is a homebrew open source 3D game engine I develop written in about 3300 lines of Haskell and 450 lines of OpenGL Shading Language.

  • Getting recursively drunk with monoids by Simon Shine

    Sam Horvath-Hunt blogged about modelling cocktails as monoids. This is a really cool example of FP modelling that I want to expand on.

  • Hacktoberfest 2020 by Tom Sydney Kerckhove

    Hacktoberfest is happening again in 2020 and CS Syd will be participating again.

  • Write a simple loop with fix by Tatsuya Hirose

    It is well known that recursive functions can be written as least fixed point of higher-order functions in domain theory.

Show & tell

  • Haskell Language Server version 0.5.0 by Luke Lau

    0.5.0 comes with a new tactics plugin which provides case splitting, homomorphic case splitting, and lambda introduction.

  • j by Vanessa McHale

    Marshal a limited subset of J arrays into Repa arrays.

  • silkscreen by Rob Rix

    Silkscreen abstracts the pretty-printing interface of prettyprinter with a Printer typeclass, allowing the definition of composable pretty-printer transformers, layering new behaviours onto the existing primitives.

  • stylish-haskell version by Jasper Van der Jeugt

    This patch swaps out the parsing library from haskell-src-exts to ghc-lib-parser, which gives us better compatibility with GHC.

Call for participation