Haskell Weekly


Issue 393 2023-11-09

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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.


  • A Fistful of Automata by Iago Leal de Freitas (originally published on October 20th, 2023)

    Recently, I have been brushing up my knowledge of Formal Languages and stumbled again into the many different faces of finite automata.

  • ​Cabal-install released by Hécate Moonlight

  • Quick and Simple Benchmarking by Monday Morning Haskell

    As a programmer, you have to constantly be asking, “How Good is my Code?”. There are a lot of different ways code can be “good” or “bad”, but one of the key indicators in many cases is the time performance of your code. How long does it take your code to run on particular inputs?

  • Stubbing I/O in Yesod by Jezen Thomas

    I’ve seen people struggle with figuring out how to stub IO actions in Yesod request handlers for writing automated tests. Here’s a simple example of one way to approach this.

  • ​The Botan Cryptography Community Project has been funded! by ApothecaLabs

    It is with great joy today that I may announce that the Botan Cryptography Community Project Proposal has been accepted for funding by the Haskell Foundation!

  • The Haskell Unfolder Episode 14: higher-kinded types by Andres Löh, Edsko de Vries

    In this episode, we are going to look at the common design pattern where we abstract all the fields of a record type over a type constructor which can then be instantiated to the identity to get the original record type back, but also to various other interesting type constructors.

  • ​Welcome to our new Executive Director, José by Richard Eisenberg

    It is my great pleasure to announce that we have hired a new Executive Director for the Haskell Foundation: José Manuel Calderón Trilla. José is a long-time Haskeller and Haskeller-educator, with a PhD from the University of York, a stint at Galois, and is currently wrapping up a lectureship at the University of Maryland.


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

In brief

  • Swarm 0.5 release by Karl Ostmo

    As a reminder, Swarm is a 2D, open-world programming and resource gathering game with a strongly-typed, functional programming language and a unique upgrade system.

Show & tell

  • DevOps Log, 2023-11-08 by Bryan Richter

    This week, I worked on GHC CI runners, the Stackage migration, and a little Cabal CI.

  • Haskell Refactoring Step-Through - Alternative Solutions by Saachi Kaup

    A blog on refactoring Haskell code posed an interesting problem. It is a variation on a standard type of problem which asks you to find the keyword present in a list of strings – namely the opposite. It asks you to find whether a string has any one of the given keywords, i.e. find if the haystack has any one needle out of a given set of needles.

Call for participation

  • FP Dag 2024 in Delft

    The Netherlands Functional Programming Day (or FP Dag) is an annual gathering of researchers, students, and practitioners sharing a common interest in functional programming. The day features talks that cover the latest advances in research, teaching and applications in the area of functional programming and (implementation of) functional languages. The FP Dag will take place on January 5th 2024, at the Technical University of Delft. Participation is free of charge, but registration is required: https://www.aanmelder.nl/fp-nl2024/subscribe There is a soft registration deadline of Friday 22 December 2023. Colleagues from neighboring countries are more than welcome to attend; the language of the FP Day is English.

  • cabal: Uniq the list of unknown extensions to avoid “Warning: Unknown extensions: TypeAbstractions, TypeAbstractions”