Haskell Weekly


Issue 285 2021-10-14

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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.


  • 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.


  • Software Engineer at ACI Learning

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

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 by Oleg Grenrus

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

  • Cabal version by Emily Pillmore

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

  • 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