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

• GHC activities report: August – September 2021 by Well-Typed

  This is the eighth edition of our GHC activities report where we describe the work on GHC and related projects that we are doing at Well-Typed. The current edition covers roughly the months of August and September 2021.

• How to protect aeson code from hash flooding by Fraser Tweedale

  A new aeson release addresses the hash flooding issue, but you need more than a version bump to ensure your programs are protected. This post outlines how aeson addressed the vulnerability and what action you need to take.

• Pattern-matching-based AST Evaluation as Prisms by ubikium

  This blog post will introduce a way to use prism-like functions to express such complex pattern-matching-based evaluation rules.

• Testing Polysemy With polysemy-check by Sandy Maguire

  By forcing yourself to think about effects, you are forced to pull concerns apart, and use the type-system to document what’s going on. But more importantly for today, it gives us a layer of indirection inside of which we can insert testing machinery.

Jobs

• Software Engineer at ACI Learning

  We are currently accepting applications for full-stack software professionals to join our small, but talented, multidisciplinary team.

• Haskell Developer at MLabs (ad)

  We are one of the leading Haskell consultancies in the fintech, blockchain and AI space, with a passion for Haskell and open source software. We are looking for a remote Haskeller to join our team. If you are excited about Haskell and are up for a new challenge, please apply here or visit our website! For any questions please email mark@mlabs.city.

• Functional Programmer at Chordify

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

In brief

• Book of Monads by Alejandro Serrano Mena

  This book provides a journey from the very first concepts, to the myriad of monads available to programmers, down to the categorical foundations.

• How and why Haskell is better (than your favorite $LANGUAGE) by vados

  Rah-Rah Haskell posts in 2021? You betcha.

• Why Haskell? by Monday Morning Haskell

  When I tell other programmers I do a lot of programming in Haskell, a common question is “Why”?

Show & tell

• aeson version 2.0.1.0 by Oleg Grenrus

  Make map type used by Object abstract so the underlying implementation can be modified, thanks to Callan McGill.

• Cabal version 3.6.2.0 by Emily Pillmore

  The Cabal team is excited to announce the release of Cabal-3.6.2.0, and cabal-install-3.6.2.0.

• linear-generics by David Feuer

  This package offers a version of GHC.Generics with two important improvements: The to, from, to1, and from1 methods have multiplicity-polymorphic types, allowing them to be used with either traditional Haskell code or linearly typed code; and the representations used for Generic1 are modified slightly.

Call for participation

• learn4haskell by Kowainik

  Learn4Haskell is a GitHub-located course that will get you into the Haskell Functional Programming world in just 4 Pull Requests.

• aeson: Add “since” information to documentation