Haskell Weekly


Issue 398 2023-12-14

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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.


  • Equivalence problems with StreamGraph by Jonathan Dowland

    The StrIoT Logical Optimiser applies a set of rewrite rules to a stream-processing program, generating a set of variants that can be reasoned about, ranked, and deployed. The problem I’ve been tackling is that a variant may appear to be semantically equivalent to another, but compare (with ==) as distinct.

  • Haskell Foundation November 2023 Update by José Manuel Calderón Trilla

    This is my first monthly update since I have started as the new executive director for the Haskell Foundation. I am currently transitioning from my previous role and will be full time by January 2024.

  • Nesting APIs and ReaderT environments with Servant by Nicolas Hery

    In this post, we look at how to structure nested APIs using Servant so that each child API builds upon the context of its parent using ReaderT environments.

  • Serializing restaurant tables in Haskell by Mark Seemann

    This article is part of a short series of articles about serialization with and without Reflection. In this instalment I’ll explore some options for serializing JSON using Aeson.

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In brief

  • Getting Amazonka S3 to work with localstack by Magnus Therning

    I’m writing this in case someone else is getting strange errors when trying to use amazonka-s3 with localstack. It took me rather too long finding the answer and neither the errors I got from Amazonka nor from localstack were very helpful.

  • IOG GHC Update #21 by IOG

    Triweekly update from the GHC DevX team at IOG.

  • mig-2.1 minimal server library by Anton Kholomiov

    I’m happy to announce a new release of the mig library. It’s a minimal and simple library to build servers. This release adds some goodies for servers that produce HTML.

Show & tell

  • DevOps Log, 2023-12-13 by Bryan Richter

    This week has been about the Stackage migration and the standard mix of new operational issues to investigate and fix.

  • Ormolu saves the day by Tom Ellis

    I had a surprising and amusing experience using Ormolu that I thought would be interesting for others to see.

Call for participation