Hierarchical Free Monads & Software Design in Functional Programming

on YouTube ↗50m

" summary

Argues that hierarchical Free Monads give clear inversion of control: business logic lives in layered free-monad languages (APL → SQL DB → beam) and interpreters mirror that hierarchy, so code stays pure, testable and refactorable. Describes an open project Eudora Hydra and a meteor-tracking demo that use beam for DB, nested interpreters, and a JSON-based trace-and-replay testing system that records effects and replays them for unit and integration tests. Claims church-encoded free monads match final-tagless performance and reports production use at Juspay, Restaumatic and Enecuum.

AI-written summary · about

" chapters (4)

1. 0:00Start
2. 9:59Haskell Libraries for Effects
3. 36:11What We Learnt
4. 38:41Performance

" related talks

• 01h 14mBeyond Free MonadsJohn DeGoes · LambdaConf Winter Retreat 2017
• 32mDiscussion: Are Free Monads Really Free?Mark Seemann, Tomas Petricek · fsharpConf 2023
• 19mFinding the Free WayDave Cleaver · Typelevel Summit NYC 2017
• 41mWhy the free Monad isn't freeKelley Robinson · Scala Days Berlin 2016
• 43mFree monad or tagless final? How not to commit to a monad too earlyAdam Warski · Scala.IO 2017
• 27mMonad Stacks or: How I Learned to Stop Worrying and Love the Free MonadHarry Laoulakos · Typelevel Summit Copenhagen 2017
• 46mMove Over Free Monads: Make Way for Free Applicatives!John A De Goes · Scala World 2015
• 01h 06mThe Evolution of EffectsNicolas Wu · Haskell 2023