Haskell Weekly

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.

Featured

• Category Theory Illustrated by Jencel P.

  Discover the beauty of mathematics through the lens of category theory with this unique exploration that goes beyond problem-solving. In this book, you’ll find a refreshing perspective on math as an art form, a language, and a way of thinking that unifies diverse fields of knowledge. Delve into the fascinating world of sets, groups, types, and partial orders, and explore the deep connections between these concepts. Whether you’re a curious beginner or a seasoned mathematician, this book offers clear explanations, diagrams, and engaging insights—it’s a journey into the heart of mathematics for everyone.

• Exported for tests only: Precise control over API visibility with custom warnings by Théophile Choutri

  Recent advances in GHC 9.8 allow library authors to control how internal data constructors can be labelled as unsafe for human consumption, while needing to be exported for test suites.

• FFT in Haskell and Futhark by Julien

  The Fourier transform is one of the fundamental tools in analysis. From the perspective of approximation theory, it gives us one of the orthogonal function bases, the natural basis for periodic functions.

• GHC version support policy by Maxim Ivanov

  I’d spent a lot more time than I’m willing to admit on locating the info table “which version is currently EOL / not EOL” for GHC. Regardless of the frequency how often one needs this information (which may range from “daily” to “never” depending on role) — when it’s needed, it better be reachable at fingertips distance. The site endoflife.date is a non-authoritative community resource, it aggregates just this sort of lifecycle information over hundreds of software projects.

In brief

• Flora 1.0.22 is here! With this release you can view security advisories for Haskell packages of the Hackage ecosystem by Théophile Choutri

• GHCup 0.1.40.0 released by Julian Ospald

• GHCup Setup GitHub Action by Julian Ospald

  A simple github action to install ghcup binary on any system and add it to PATH.

• Stack 3.3.1 by Mike Pilgrem

Show & tell

• Dataframes in Haskell by Michael Chavinda

  I’ll submit this proposal as a Github issue for the Haskell foundation as well but posting here for visibility too.

• I wrote a novel… by Teby

  As the title says, there’s a new book out there. It’s not written from the perspective of a Haskell expert, nor a newcomer, but a pragmatist trying to make sense of it while solving challenges on the job. It’s equal parts urban fiction and Haskell book.

Call for participation

• ghcup-hs: Use jsonpath for getting/setting config values