shapeless: generic programming for Scala

shapeless is a type class and dependent type based generic programming library for Scala. It had its origins in several talks by Miles Sabin (@milessabin), given over the course of 2011, on implementing scrap your boilerplate and higher rank polymorphism in Scala. Since then it has evolved from being a resolutely experimental project into a library which, while still testing the limits of what's possible in Scala, is being used widely in production systems wherever there are arities to be abstracted over and boilerplate to be scrapped.

Projects which use shapeless

There is a wide variety of projects which use shapeless in one way or another ... see the incomplete list of projects for ideas and inspiration. If you are using shapeless and your project isn't listed yet, please add it.

Finding out more about the project

The feature overview for shapeless-2.0.0 provides a very incomplete introduction to shapeless. Additional information can be found in subsequent release notes. If you are upgrading from shapeless-2.0.0 you will find the migration guide useful. We're not satisfied with the current state of the documentation and would love help in improving it. You can find an excellent guide to Shapeless here: The Type Astronaut's Guide to Shapeless.

shapeless is part of the Typelevel family of projects. It is an Open Source project under the Apache License v2, hosted on github. Binary artefacts are published to the Sonatype OSS Repository Hosting service and synced to Maven Central.

Most discussion of shapeless and generic programming in Scala happens on the #shapless channel of the Typelevel Discord. There is also a mailing list and Gitter, but these are largely dormant now that most activity has moved to Discord. Questions about shapeless are often asked and answered under the shapeless tag on StackOverflow. Some articles on the implementation techniques can be found on Miles's blog, and Olivera, Moors and Odersky, Type Classes as Object and Implicits is useful background material.

Participation

The shapeless project supports the Scala Code of Conduct and wants all of its channels (mailing list, Gitter, IRC, github, etc.) to be welcoming environments for everyone.

Whilst shapeless is a somewhat "advanced" Scala library, it is a lot more approachable than many people think. Contributors are usually available to field questions, give advice and discuss ideas on the #shapeless Discord channel, and for people wanting to take their first steps at contributing we have a selection of open issues flagged up as being good candidates to take on. No contribution is too small, and guidance is always available.

Using shapeless

Binary release artefacts are published to the Sonatype OSS Repository Hosting service and synced to Maven Central. Snapshots of the main branch are built using GitHub actions and automatically published to the Sonatype OSS Snapshot repository.

Try shapeless with an Ammonite instant REPL

The quickest way to get to a REPL prompt with the latest version of shapeless on the class path is to run the provided "try shapeless" script, which has no dependencies other than an installed JDK. This script downloads and installs coursier and uses it to fetch the Ammonite REPL and the latest version of shapeless. It then drops you immediately into a REPL session,

% curl -s https://raw.githubusercontent.com/milessabin/shapeless/main/scripts/try-shapeless.sh | bash
Loading...
Compiling (synthetic)/ammonite/predef/interpBridge.sc
Compiling (synthetic)/ammonite/predef/replBridge.sc
Compiling (synthetic)/ammonite/predef/DefaultPredef.sc
Compiling /home/miles/projects/shapeless/(console)
Welcome to the Ammonite Repl 1.6.8
(Scala 2.13.1 Java 1.8.0_212)
If you like Ammonite, please support our development at www.patreon.com/lihaoyi
@ 23 :: "foo" :: true :: HNil 
res0: Int :: String :: Boolean :: HNil = 23 :: "foo" :: true :: HNil

@ Bye!
%

shapeless-2.3.3 with SBT

To include the Sonatype repositories in your SBT build you should add,

resolvers ++= Seq(
  Resolver.sonatypeRepo("releases"),
  Resolver.sonatypeRepo("snapshots")
)

Builds are available for Scala 2.11.x, 2.12.x and 2.13.x. The main line of development for shapeless 2.3.3 is Scala 2.13.2.

scalaVersion := "2.13.5"

libraryDependencies ++= Seq(
  "com.chuusai" %% "shapeless" % "2.3.3"
)

For using snapshots of Shapeless you should add,

scalaVersion := "2.13.5"

libraryDependencies ++= Seq(
  "com.chuusai" %% "shapeless" % "2.4.0-SNAPSHOT"
)

shapeless-2.3.3 with Maven

shapeless is also available for projects using the Maven build tool via the following dependency,

<dependency>
  <groupId>com.chuusai</groupId>
  <artifactId>shapeless_2.13</artifactId>
  <version>2.3.3</version>
</dependency>

Older releases

Please use a current release if possible. If unavoidable, you can find usage information for older releases on the shapeless wiki.

Building shapeless

shapeless is built with SBT 1.3.10 or later, and its main branch is built with Scala 2.13.2 by default but also cross-builds for 2.11.12 and 2.12.12.

Contributors

Alex Zorab alec.zorab@gmail.com @aleczorab
Alessandro Lacava alessandrolacava@gmail.com @lambdista
Alexander Konovalov alex.knvl@gmail.com @alexknvl
Alexandre Archambault alexandre.archambault@gmail.com @alxarchambault
Alistair Johnson alistair.johnson@johnsonusm.com @AlistairUSM
Allison H. allisonhb@gmx.com
Alois Cochard alois.cochard@gmail.com @aloiscochard
Andreas Koestler andreas.koestler@gmail.com @AndreasKostler
Andrew Brett github@bretts.org @Ephemerix
Aristotelis Dossas teldosas@gmail.com @teldosas
Arya Irani arya.irani@gmail.com @aryairani
Ben Hutchison brhutchison@gmail.com @ben_hutchison
Ben James ben.james@guardian.co.uk @bmjames
Brian McKenna brian@brianmckenna.org @puffnfresh
Brian Zeligson brian.zeligson@gmail.com @beezee
Bryn Keller xoltar@xoltar.org @brynkeller
Carlos Quiroz @carlosmquiroz
Chris Hodapp clhodapp1@gmail.com @clhodapp
Cody Allen ceedubs@gmail.com @fourierstrick
Dale Wijnand dale.wijnand@gmail.com @dwijnand
Daniel Urban urban.dani@gmail.com
Dario Rexin dario.rexin@r3-tech.de @evonox
Dave Gurnell d.j.gurnell@gmail.com @davegurnell
David Barri japgolly@gmail.com @japgolly
Denis Mikhaylov notxcain@gmail.com @notxcain
Dmitry Kovalev kdn.kovalev@gmail.com
Eugene Burmako xeno.by@gmail.com @xeno_by
Fabio Labella fabio.labella2@gmail.com @SystemFw
Filipe Nepomuceno filinep@gmail.com
Frank S. Thomas frank@timepit.eu @fst9000
George Leontiev folone@gmail.com @folone
Georgi Krastev joro.kr.21@gmail.com @Joro_Kr
Hamish Dickenson hamish.dickson@gmail.com @hamishdickson
Harrison Houghton hhoughton@learningobjects.com
Howard Branch purestgreen@gmail.com @purestgreen
Huw Giddens hgiddens@gmail.com
Hywel Andrews hywel.andrews@agoda.com
Ievgen Garkusha ievgen@riskident.com
Jacob Barber jacoby6000@gmail.com @jacoby6000
Jason Zaugg jzaugg@gmail.com @retronym
Jean-Baptiste Giraudeau jb@giraudeau.info @jb9i
Jean-Remi Desjardins jeanremi.desjardins@gmail.com @jrdesjardins
Jeff Martin jmartin@homeaway.com
Jeff Wilde jeff@robo.ai
Jeremy R. Smith jeremyrsmith@gmail.com @jeremyrsmith
Jisoo Park xxxyel@gmail.com @guersam
Johannes Rudolph johannes.rudolph@gmail.com @virtualvoid
Johnny Everson khronnuz@gmail.com @johnny_everson
Jolse Maginnis jolse.maginnis@pearson.com @doolse2
Joni Freeman joni.freeman@ri.fi @jonifreeman
Joseph Price josephprice@iheartmedia.com
Juan José Vázquez Delgado juanjo.vazquez.delgado@tecsisa.com @juanjovazquez
Julien Tournay boudhevil@gmail.com @skaalf
Jules Gosnell jules_gosnell@yahoo.com
Kailuo Wang kailuo.wang@gmail.com @kailuowang
Kazuki Moriyama pharcydetip@gmail.com @kazchimo
Kenji Yoshida 6b656e6a69@gmail.com @xuwei_k
Kevin Wright kev.lee.wright@gmail.com @thecoda
Lars Hupel lars.hupel@mytum.de @larsr_h
Lukasz Golebiewski lukasz.golebiewski@gmail.com @LukaszGobiewsk1
Mario Pastorelli mario.pastorelli@teralytics.ch @mapastr
Matthew Taylor matthew.t@tbfe.net
Mathias Doenitz mathias@spray.io @sirthias
Michael Donaghy md401@srcf.ucam.org
Michael Pilquist mpilquist@gmail.com @mpilquist
Michael Zuber michaelg.zuber@gmail.com @mgzuber91
Mike Limansky mike.limansky@gmail.com @mike_limansky
Miles Sabin miles@milessabin.com @milessabin
n4to4 n4to4k@gmail.com @n4to4
Neville Li neville@spotify.com @sinisa_lyh
Nikolas Evangelopoulos nikolas@jkl.gr
Oleg Aleshko olegych@tut.by @OlegYch
Olivier Blanvillain olivier.blanvillain@gmail.com
Olli Helenius liff@iki.fi @ollijh
Owein Reese owreese@gmail.com @OweinReese
Paolo G. Giarrusso p.giarrusso@gmail.com @blaisorblade
Pascal Voitot pascal.voitot.dev@gmail.com @mandubian
Pavel Chlupacek pavel.chlupacek@spinoco.com @pacmanius
Peter Neyens peter.neyens@gmail.com @pneyens
Peter Schmitz petrischmitz@gmail.com @peterschmitz_
Renato Cavalcanti renato@strongtyped.io @renatocaval
Rob Norris rob_norris@mac.com @tpolecat
Robert Hensing spam@roberthensing.nl
Ronan Michaux ronan_michaux@yahoo.com @ronan_michaux
Ryadh Khsib ryadh.khsib@gmail.com
Ryo Hongo ryoppy0516@gmail.com @ryoppy516
Sam Halliday sam.halliday@gmail.com @fommil
Sarah Gerweck sarah.a180@gmail.com @SGerweck
Sébastien Doeraene sjrdoeraene@gmail.com @sjrdoeraene
Simon Hafner hafnersimon@gmail.com @reactormonk
Stacy Curl stacy.curl@gmail.com @stacycurl
Stanislav Savulchik s.savulchik@gmail.com @savulchik
Stephen Compall scompall@nocandysw.com @S11001001
Tin Pavlinic tin.pavlinic@gmail.com @triggerNZ
Tom Switzer thomas.switzer@gmail.com @tixxit
Tomas Mikula tomas.mikula@gmail.com @tomas_mikula
Travis Brown travisrobertbrown@gmail.com @travisbrown
Valentin Kasas valentin.kasas@gmail.com @ValentinKasas
Valerian Barbot valerian.barbot@onzo.com @etaty
Valy Diarrassouba v.diarrassouba@gmail.com
Vladimir Matveev vladimir.matweev@gmail.com @netvlm
Vladimir Pavkin vpavkin@gmail.com @vlpavkin
William Harvey harveywi@cse.ohio-state.edu
Yang Bo (杨博) pop.atry@gmail.com @Atry
Zainab Ali zainab.ali.london@gmail.com @zainabali

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