Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/kitlangton/zio-magic
Construct ZLayers automagically (w/ helpful compile-time errors)
https://github.com/kitlangton/zio-magic
Last synced: 27 days ago
JSON representation
Construct ZLayers automagically (w/ helpful compile-time errors)
- Host: GitHub
- URL: https://github.com/kitlangton/zio-magic
- Owner: kitlangton
- License: apache-2.0
- Created: 2021-01-17T01:30:10.000Z (almost 4 years ago)
- Default Branch: master
- Last Pushed: 2023-11-17T20:00:06.000Z (12 months ago)
- Last Synced: 2023-12-16T21:01:02.913Z (11 months ago)
- Language: Scala
- Homepage:
- Size: 293 KB
- Stars: 251
- Watchers: 8
- Forks: 20
- Open Issues: 21
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# 🪄 zio-magic
[![Release Artifacts][Badge-SonatypeReleases]][Link-SonatypeReleases]
[![Snapshot Artifacts][Badge-SonatypeSnapshots]][Link-SonatypeSnapshots]
***ANNOUNCEMENT: This library is officially included as a first-class feature of ZIO 2.0 😊***
Construct ZLayers _automagically_, with friendly compile-time hints!
```sbt
// build.sbt
libraryDependencies += "io.github.kitlangton" %% "zio-magic" % "0.3.12"
```
## What's all this then?
```scala
// Given a dependency graph (Cake needs Chocolate & Flour, which in turn need Spoon)*
//
// Cake
// / \
// Chocolate Flour
// | |
// Spoon Spoon
//
// *Not an actual recipe.
import zio._
import zio.magic._
def run(args: List[String]): URIO[ZEnv, ExitCode] = {
// An effect requiring Cake and Console. Yum!
val program: URIO[Console with Cake, Unit] =
Cake.isDelicious.flatMap { bool => console.putStrLn(s"Cake is delicious: $bool") }
// The old way
val manually: ULayer[Cake with Console] =
((Spoon.live >>> Flour.live) ++ (Spoon.live >>> Chocolate.live)) >>> Cake.live ++ Console.live
// The magical way (The order doesn't matter)
val magically: UIO[Unit] =
program.inject(
Cake.live,
Flour.live,
Chocolate.live,
Spoon.live,
Console.live
)
magically.exitCode
}
```
----
And if you leave something off, a **compile time clue**!
```scala
val magically: UIO[Unit] =
program.inject(
Cake.live,
//Flour.live, <-- Oops
Chocolate.live,
Spoon.live,
Console.live
)
```
```sh
ZLayer Wiring Error
> provide zio.magic.Example.Flour.Service
> for Cake.live
```
----
Versus leaving out a dependency when manually constructing your layer...
```scala
val manually: ULayer[Cake with Console] =
(Flour.live ++ (Spoon.live >>> Chocolate.live)) >>> Cake.live ++ Console.live
// ^ A Spoon is missing here!
```
```shell
type mismatch;
found : zio.ZLayer[zio.magic.Example.Spoon.Spoon with Any,Nothing,zio.magic.Example.Cake.Cake with zio.console.Console]
(which expands to) zio.ZLayer[zio.Has[zio.magic.Example.Spoon.Service] with Any,Nothing,zio.Has[zio.magic.Example.Cake.Service] with zio.Has[zio.console.Console.Service]]
required: zio.ULayer[zio.magic.Example.Cake.Cake with zio.console.Console]
(which expands to) zio.ZLayer[Any,Nothing,zio.Has[zio.magic.Example.Cake.Service] with zio.Has[zio.console.Console.Service]]
((Flour.live) ++ (Spoon.live >>> Chocolate.live)) >>> Cake.live ++ Console.live
```
## Also
You can also directly construct a ZLayer (However you must annotate the call to `ZLayer.wire[LikeThis]`, because macros).
```scala
val layer = ZLayer.wire[Flour with Console](Console.live, Flour.live, Spoon.live)
```
To construct `URLayer[In, Out]` use `ZLayer.wireSome[In, Out]` this way:
```scala
val layer = ZLayer.wireSome[CommonEnv, Flour with Console](Console.live, Flour.live, Spoon.live)
```
Alternatively you can provide environment partially with `injectSome[Rest](l1, l2, l3)` - similarly to `.provideSomeLayer`.
There's also `.injectCustom` for which behaves similarly to `.provideCustomLayer`, only it also provides `ZEnv.any` to all transitive dependencies.
```scala
val program: URIO[Console with Car, Unit] = ???
val carLayer: URLayer[Blocking with Wheels, Car] = ???
val wheelLayer: ULayer[Wheels] = ???
// The ZEnv you use later will provide both Blocking to carLayer and Console to the program
val provided: URIO[ZEnv, Unit] =
program.injectCustom(carLayer, wheelLayer)
```
## Specs
`inject`, `injectCustom`, `injectSome`, `injectShared`, `injectCustomShared` and `injectSomeShared` all work for zio-test's `Spec`.
## Debug!
Try `ZLayer.wireDebug[Cake]` or `ZLayer.wireSomeDebug[Blocking with Console, Cake]` to print out a pretty tree! _Ooh la la!_
```shell
ZLayer Wiring Graph
===================
â—‰ Cake.live
├─◑ Flour.live
│ ├─◑ Spoon.live
│ │ ╰─◑ Blocking.live
│ ╰─◑ Console.live
╰─◑ Berries.live
╰─◑ Spoon.live
╰─◑ Blocking.live
```
**Let me know if you can think of any helpful variants, and I'll give 'em a whirl!**
[Badge-SonatypeReleases]: https://img.shields.io/nexus/r/https/oss.sonatype.org/io.github.kitlangton/zio-magic_2.13.svg "Sonatype Releases"
[Badge-SonatypeSnapshots]: https://img.shields.io/nexus/s/https/oss.sonatype.org/io.github.kitlangton/zio-magic_2.13.svg "Sonatype Snapshots"
[Link-SonatypeSnapshots]: https://oss.sonatype.org/content/repositories/snapshots/io/github/kitlangton/zio-magic_2.13/ "Sonatype Snapshots"
[Link-SonatypeReleases]: https://oss.sonatype.org/content/repositories/releases/io/github/kitlangton/zio-magic_2.13/ "Sonatype Releases"