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

• Configuration of a Polysemy application by Thomas Mahler

  One question that came up: why did I explicitly load configuration before starting the Polysemy effect interpreter? Wouldn’t it be much more in line with the overall idea of my Polysemy Clean Architecture to handle this loading also as an effect?

• The Lazy Way to Solve Differential Equations by Iago Leal de Freitas

  By the end of this post we gonna be able to solve this differential equation simply by writing the equivalent Haskell definition

• One of a Kind: An Introduction to Kinds in Haskell

  Just as Haskell has a type system to classify values, it has a kind system to classify types. It provides a way to reason about what types make sense to construct.

• Parallelising Source Positions by Benjamin Hodgson

  My parsing library Pidgin has some infrastructure to track positions in a textual input file, for the purposes of error reporting.

• Universal and Existential Quantification in Haskell by Stepan Prudnikov

  In logic, there are two common quantifiers: the universal quantifier and the existential quantifier. You might recognize them as ∀ (for all) and ∃ (there exists).

Jobs

• Software Engineer at Freckle

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

In brief

• Data Structures: Hash Maps! by Monday Morning Haskell

  Today we’re taking the next logical step in the progression and looking at Hash Maps. Starting later this week, we’ll start looking as lesser-known Haskell structures that don’t fit some of the common patterns we’ve been seeing so far!

• Episode 15 by Facundo Dominguez

  Facundo Dominguez is interviewed by Niki Vazou and Joachim Breitner. Facundo Dominguez tells us the difference between STM and SMT.

• Haskell Foundation board minutes, July 14, 2022 by Théophile Choutri

  You can check out the minutes and agenda for the Board meeting that took place on the 2022-07-14.

• Haskell Foundation DevOps Weekly Log, 2022-07-15 by Bryan Richter

  This week I moved into phase 2 of CI failure reporting. Following on last week’s CI failure dashboard, I’m now working on a system to backfill new errors as they are categorized.

Show & tell

• effectful: an easy to use, performant extensible effects library by Andrzej Rybczak

  Hey everyone, It’s taken ages, but finally the initial release of the effectful library is here.

• filepath-1.4.100.0 released by Julian Ospald

  This release implements support for the “abstract filepath proposal” (AFPP). There are no breaking changes in the existing API.

• ghc-plugin-non-empty by Dmitrii Kovanikov

  GHC Compiler Plugin for automatically converting list literals to the NonEmpty type from the Data.List.NonEmpty module in base.

• servant-oauth2: first release by Noon van der Silk

  It’s a light-weight wrapper around wai-middleware-auth, but done within the context of “modern servant”, so you can lift authentication/authorisation information to the type level.

• stargaze-cli by Qiao Wang

  Stargaze is a CLI tool to help you manage your starred projects on GitHub.

Call for participation

• dbmonitor: Different colors in logs
• doctest-parallel: Turn some comments into haddock