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 shapeless Gitter channel. There is also a mailing list and IRC channel, but these are largely dormant now that most activity has moved to Gitter. 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 Gitter 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 master branch are built using Travis CI 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/master/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 := "2.13.2"
libraryDependencies ++= Seq(
"com.chuusai" %% "shapeless" % "2.3.3"
)
For using snapshots of Shapeless you should add,
scalaVersion := "2.13.2"
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 master 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 [email protected] @aleczorab
- Alessandro Lacava [email protected] @lambdista
- Alexander Konovalov [email protected] @alexknvl
- Alexandre Archambault [email protected] @alxarchambault
- Alistair Johnson [email protected] @AlistairUSM
- Allison H. [email protected]
- Alois Cochard [email protected] @aloiscochard
- Andreas Koestler [email protected] @AndreasKostler
- Andrew Brett [email protected] @Ephemerix
- Aristotelis Dossas [email protected] @teldosas
- Arya Irani [email protected] @aryairani
- Ben Hutchison [email protected] @ben_hutchison
- Ben James [email protected] @bmjames
- Brian McKenna [email protected] @puffnfresh
- Brian Zeligson [email protected] @beezee
- Bryn Keller [email protected] @brynkeller
- Carlos Quiroz @carlosmquiroz
- Chris Hodapp [email protected] @clhodapp
- Cody Allen [email protected] @fourierstrick
- Dale Wijnand [email protected] @dwijnand
- Daniel Urban [email protected]
- Dario Rexin [email protected] @evonox
- Dave Gurnell [email protected] @davegurnell
- David Barri [email protected] @japgolly
- Denis Mikhaylov [email protected] @notxcain
- Dmitry Kovalev [email protected]
- Eugene Burmako [email protected] @xeno_by
- Fabio Labella [email protected] @SystemFw
- Filipe Nepomuceno [email protected]
- Frank S. Thomas [email protected] @fst9000
- George Leontiev [email protected] @folone
- Georgi Krastev [email protected] @Joro_Kr
- Hamish Dickenson [email protected] @hamishdickson
- Harrison Houghton [email protected]
- Howard Branch [email protected] @purestgreen
- Huw Giddens [email protected]
- Hywel Andrews [email protected]
- Ievgen Garkusha [email protected]
- Jacob Barber [email protected] @jacoby6000
- Jason Zaugg [email protected] @retronym
- Jean-Baptiste Giraudeau [email protected] @jb9i
- Jean-Remi Desjardins [email protected] @jrdesjardins
- Jeff Martin [email protected]
- Jeff Wilde [email protected]
- Jeremy R. Smith [email protected] @jeremyrsmith
- Jisoo Park [email protected] @guersam
- Johannes Rudolph [email protected] @virtualvoid
- Johnny Everson [email protected] @johnny_everson
- Jolse Maginnis [email protected] @doolse2
- Joni Freeman [email protected] @jonifreeman
- Joseph Price [email protected]
- Juan José Vázquez Delgado [email protected] @juanjovazquez
- Julien Tournay [email protected] @skaalf
- Jules Gosnell [email protected]
- Kailuo Wang [email protected] @kailuowang
- Kazuki Moriyama [email protected] @kazchimo
- Kenji Yoshida [email protected] @xuwei_k
- Kevin Wright [email protected] @thecoda
- Lars Hupel [email protected] @larsr_h
- Lukasz Golebiewski [email protected] @LukaszGobiewsk1
- Mario Pastorelli [email protected] @mapastr
- Matthew Taylor [email protected]
- Mathias Doenitz [email protected] @sirthias
- Michael Donaghy [email protected]
- Michael Pilquist [email protected] @mpilquist
- Michael Zuber [email protected] @mgzuber91
- Mike Limansky [email protected] @mike_limansky
- Miles Sabin [email protected] @milessabin
- n4to4 [email protected] @n4to4
- Neville Li [email protected] @sinisa_lyh
- Nikolas Evangelopoulos [email protected]
- Oleg Aleshko [email protected] @OlegYch
- Olivier Blanvillain [email protected]
- Olli Helenius [email protected] @ollijh
- Owein Reese [email protected] @OweinReese
- Paolo G. Giarrusso [email protected] @blaisorblade
- Pascal Voitot [email protected] @mandubian
- Pavel Chlupacek [email protected] @pacmanius
- Peter Neyens [email protected] @pneyens
- Peter Schmitz [email protected] @peterschmitz_
- Renato Cavalcanti [email protected] @renatocaval
- Rob Norris [email protected] @tpolecat
- Robert Hensing [email protected]
- Ronan Michaux [email protected] @ronan_michaux
- Ryadh Khsib [email protected]
- Ryo Hongo [email protected] @ryoppy516
- Sam Halliday [email protected] @fommil
- Sarah Gerweck [email protected] @SGerweck
- Sébastien Doeraene [email protected] @sjrdoeraene
- Simon Hafner [email protected] @reactormonk
- Stacy Curl [email protected] @stacycurl
- Stanislav Savulchik [email protected] @savulchik
- Stephen Compall [email protected] @S11001001
- Tin Pavlinic [email protected] @triggerNZ
- Tom Switzer [email protected] @tixxit
- Tomas Mikula [email protected] @tomas_mikula
- Travis Brown [email protected] @travisbrown
- Valentin Kasas [email protected] @ValentinKasas
- Valerian Barbot [email protected] @etaty
- Valy Diarrassouba [email protected]
- Vladimir Matveev [email protected] @netvlm
- Vladimir Pavkin [email protected] @vlpavkin
- William Harvey [email protected]
- Yang Bo (杨博) [email protected] @Atry
- Zainab Ali [email protected] @zainabali