polysemy

Tech stack & purpose

Polysemy is a Haskell library for writing domain-specific languages that separate business logic from implementation details, allowing code to be reused as libraries. It provides higher-order effects with minimal boilerplate, positioning itself as an improvement over existing approaches like `mtl`, `freer-simple`, and `fused-effects` by avoiding O(n²) instances problems and supporting multiple copies of the same effect without functional dependencies. The project is built in Haskell and comes with an optional companion typechecker plugin, `polysemy-plugin`, which disambiguates effect usage to improve type inference. Sandy Maguire is identified as the author.

Community & reference links

• classy lenses
• okmij.org/ftp/Haskell/extensible/exteff.pdf
• okmij.org/ftp/Haskell/extensible/more.pdf
• some
• blog posts
• funprog.zulipchat.com/#narrow/stream/216942-Polysemy
• github.com/fused-effects/fused-effects
• bigger, multi-module programs
• `polysemy-plugin`
• github.com/lexi-lambda/freer-simple
• visible drop in performance
• Necessary Language Extensions
• hackage.haskell.org/package/mtl
• `polysemy`
• hackage.haskell.org/package/polysemy-plugin
• `simple-effects`
• tutorial
• hasura.github.io/eff/Control-Effect.html
• people.cs.kuleuven.be/~tom.schrijvers/Research/papers/mpc2015.pdf
• Porting to Polysemy
• **optimizations** we depend on
• wiki.nixos.org/wiki/Flakes
• www.cs.ox.ac.uk/people/nicolas.wu/papers/Scope.pdf
• `ReaderT` pattern
• trouble with typed errors
• performance implementation
• great talk

Languages

Contributors (top 30 of 46)

• 
  Sandy Maguire306 commits · 1,312 followers
• 
  Torsten Schmits63 commits · 102 followers
• 
  Georgi Lyubenov43 commits · 106 followers
• KingoftheHomeless35 commits
• 
  TheMatten33 commits · 19 followers
• 
  Samuel Gélineau10 commits · 283 followers
• Keagan McClelland7 commits
• 
  Felix Yan6 commits · 3,361 followers
• Jack Henahan5 commits
• 
  fendor3 commits · 79 followers
• 
  jkachmar3 commits · 167 followers
• Sophie Taylor3 commits
• Daniel Firth2 commits
• 
  Silvan Mosberger2 commits · 455 followers
• Jeremy Schlatter2 commits
• Juan Paucar2 commits
• Chris Sasarak2 commits
• Andrew Miller2 commits
• Joe Hermaszewski2 commits
• 
  Armando Santos2 commits · 135 followers
• 
  Kevin Quick1 commits · 60 followers
• 
  Vekhir1 commits · 2 followers
• Dieter Houthooft1 commits
• Kit Langton1 commits
• Samuel Evans-Powell1 commits
• 
  Jason1 commits · 65 followers
• Armando Ramirez1 commits
• 
  Connor James1 commits · 21 followers
• 
  Jörg Thalheim1 commits · 1,460 followers
• 
  Morrow1 commits · 31 followers