shapeless-3
所属分类：图形图象
开发工具：Scala
文件大小：0KB
下载次数：0
上传日期：2023-07-17 04:15:05
上 传 者：
sh-1993
说明： Scala的通用编程，
(Generic programming for Scala,)
文件列表:
.jvmopts (75, 2023-12-14)
.mergify.yml (1479, 2023-12-14)
.scalafmt.conf (637, 2023-12-14)
CODE_OF_CONDUCT.md (834, 2023-12-14)
build.sbt (5682, 2023-12-14)
docs/ (0, 2023-12-14)
docs/index.md (98, 2023-12-14)
modules/ (0, 2023-12-14)
modules/deriving/ (0, 2023-12-14)
modules/deriving/src/ (0, 2023-12-14)
modules/deriving/src/main/ (0, 2023-12-14)
modules/deriving/src/main/scala/ (0, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/ (0, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/deriving/ (0, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/deriving/annotation.scala (15548, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/deriving/deriving.scala (2521, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/deriving/internals/ (0, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/deriving/internals/erased.scala (12966, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/deriving/internals/kinds.scala (770, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/deriving/internals/reflectionutils.scala (2745, 2023-12-14)
modules/deriving/src/main/scala/shapeless3/deriving/kinds.scala (30637, 2023-12-14)
modules/deriving/src/test/ (0, 2023-12-14)
modules/deriving/src/test/scala/ (0, 2023-12-14)
modules/deriving/src/test/scala/shapeless3/ (0, 2023-12-14)
modules/deriving/src/test/scala/shapeless3/deriving/ (0, 2023-12-14)
modules/deriving/src/test/scala/shapeless3/deriving/adts.scala (2609, 2023-12-14)
modules/deriving/src/test/scala/shapeless3/deriving/annotation.scala (7180, 2023-12-14)
modules/deriving/src/test/scala/shapeless3/deriving/deriving.scala (14209, 2023-12-14)
modules/deriving/src/test/scala/shapeless3/deriving/instances.scala (3002, 2023-12-14)
modules/deriving/src/test/scala/shapeless3/deriving/type-classes.scala (25354, 2023-12-14)
modules/test/ (0, 2023-12-14)
modules/test/src/ (0, 2023-12-14)
modules/test/src/main/ (0, 2023-12-14)
modules/test/src/main/scala/ (0, 2023-12-14)
... ...
# shapeless: generic programming for Scala
[](https://discord.gg/bSQBZA3Ced)
[](https://gitter.im/milessabin/shapeless)
[](https://maven-badges.herokuapp.com/maven-central/org.typelevel/shapeless3-deriving_3)
[](https://www.scala-js.org)
**shapeless** is a type class and dependent type based generic programming
library for Scala.
**This repository contains shapeless 3 for Scala 3. For shapeless 2 see its own
[repository](https://github.com/milessabin/shapeless).**
Please open issues and PRs for shapeless 2 in the old repository.
shapeless 3 was developed as part of a collaboration with Martin Odersky's
group at EPFL LAMP to develop [language-level support][mirror] for generic
programming for Scala 3. shapeless 3 is included in the [Dotty Community
Build][communitybuild].
## Current status
Included so far is a full implementation of type class derivation as flexible
as that of shapeless 2, but generalized across kinds. For derivation of regular
ADTs and type classes compile- and runtime performance are dramatically
improved over shapeless 2. This comes with a significantly reduced binary
footprint in client code.
Support is provided for deriving type classes indexed by types of kinds `*`
(eg. `Monoid`, `Eq`, `Show`), `* -> *` (eg. `Functor`, `Traverse`, `Monad`)
`(* -> *) -> *)`, (eg. `FunctorK`, aka `HFunctor` in Haskell) and `* -> * -> *`
(eg. `Bifunctor`). Support for additional kinds can be added fairly
straightforwardly with a small amount of additional boilerplate for each kind.
The first two of these kinds equal the power of shapeless 2's `Generic` and
`Generic1` (see their use in the [Kittens][kittens] type class derivation
library for [Cats][cats]). The remainder go considerably beyond.
Using shapeless 3 the derivation of a monoid for a Scala ADT is as simple as,
```scala
import shapeless3.deriving.*
// Type class definition, eg. from Cats
trait Monoid[A]:
def empty: A
def combine(x: A, y: A): A
extension (x: A) def |+| (y: A): A = combine(x, y)
object Monoid:
given Monoid[Unit] with
def empty: Unit = ()
def combine(x: Unit, y: Unit): Unit = ()
given Monoid[Boolean] with
def empty: Boolean = false
def combine(x: Boolean, y: Boolean): Boolean = x || y
given Monoid[Int] with
def empty: Int = 0
def combine(x: Int, y: Int): Int = x+y
given Monoid[String] with
def empty: String = ""
def combine(x: String, y: String): String = x+y
given monoidGen[A](using inst: K0.ProductInstances[Monoid, A]): Monoid[A] with
def empty: A =
inst.construct([t] => (ma: Monoid[t]) => ma.empty)
def combine(x: A, y: A): A =
inst.map2(x, y)([t] => (mt: Monoid[t], t0: t, t1: t) => mt.combine(t0, t1))
inline def derived[A](using gen: K0.ProductGeneric[A]): Monoid[A] = monoidGen
// ADT definition
case class ISB(i: Int, s: String, b: Boolean) derives Monoid
val a = ISB(23, "foo", true)
val b = ISB(13, "bar", false)
val c = a |+| b // == ISB(36, "foobar", true)
```
A similar derivation for [`Functor`][functor] allows the following,
```scala
enum Opt[+A] derives Functor:
case Sm[+A](value: A)
case Nn
Sm("foo").map(_.length) // == Sm(3)
```
We can even derive [higher order functors][functork] in almost exactly the same
way,
```scala
// An Option like type, with a default
enum OptionD[T]:
case Given(value: T)
case Default(value: T)
def fold: T = this match {
case Given(t) => t
case Default(t) => t
}
object OptionD:
val fold: OptionD ~> Id = [t] => (ot: OptionD[t]) => ot.fold
// A data type parameterized with an effect
case class OrderF[F[_]](
item: F[String],
quantity: F[Int]
) derives FunctorK
val incompleteOrder = OrderF(Given("Epoisse"), Default(1))
val completeOrder = FunctorK[OrderF].mapK(incompleteOrder)(OptionD.fold)
// == OrderF[Id]("Epoisse", 1)
```
## Getting started
shapeless 3 is available for Scala 3.0.0 for the JVM and for Scala.js 1.5.0+.
To include the deriving module in your project add the following to your build,
```
libraryDependencies ++= Seq("org.typelevel" %% "shapeless3-deriving" % "3.0.1")
```
## Finding out more about the project
shapeless is part of the [Typelevel][typelevel] family of projects. It is an
Open Source project under the Apache License v2, hosted on [GitHub][source].
Binary artefacts are published to the [Sonatype OSS Repository Hosting
service][sonatype] and synced to Maven Central.
Most discussion of shapeless and generic programming in Scala happens on the
shapeless channel of the [Typelevel Discord][discord].
## Participation
The shapeless project supports the [Scala Code of Conduct][codeofconduct] and
wants all of its channels (Gitter, github, etc.) to be welcoming environments
for everyone.
[codeofconduct]: https://www.scala-lang.org/conduct/
[typelevel]: http://typelevel.org/
[source]: https://github.com/typelevel/shapeless-3
[sonatype]: https://oss.sonatype.org/index.html#nexus-search;quick~shapeless
[gitter]: https://gitter.im/milessabin/shapeless
[discord]: https://discord.gg/bSQBZA3Ced
[mirror]: https://dotty.epfl.ch/docs/reference/contextual/derivation.html
[communitybuild]: https://github.com/lampepfl/dotty/tree/master/community-build/community-projects
[kittens]: https://github.com/typelevel/kittens
[cats]: https://github.com/typelevel/cats
[functor]: https://github.com/typelevel/shapeless-3/blob/505d44658d907c8ce193b6e66a4a9e6396ba0d9a/modules/deriving/src/test/scala/shapeless3/deriving/type-classes.scala#L137-L158
[functork]:https://github.com/typelevel/shapeless-3/blob/505d44658d907c8ce193b6e66a4a9e6396ba0d9a/modules/deriving/src/test/scala/shapeless3/deriving/type-classes.scala#L290-L308
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