Arrow Optics. Transforming and computing over immutable data models in Kotlin
Arrow Optics provides an automatic DSL that allows users to use . notation when accessing,
composing, and transforming deeply nested immutable data structures.
Optics also offers all the base types such as Lens, Prism, and others from which we can generalize accessing and
traversing deep values in sealed and data classes models.
// an immutable value with very nested components
val john = Employee("John Doe", Company("Kategory", Address("Functional city", Street(42, "lambda street"))))
// an Optional points to one place in the value
val optional: Optional<Employee, String> = Employee.company.address.street.name
// and now you can modify into a new copy without nested 'copy's!
optional.modify(john, String::toUpperCase)
Scroll down and learn what Arrow Optics can do for you(r code)!
Arrow Optics Overview
Quick Start
Additional information
Optics DSL for Values
Focus and modification
Focus and construction
- Prism: focus on optional value and build it
Single behavior
- Getter: focus on one value
- OptionalGetter: focus on optional value
- Setter: modify one value
Optics DSL for Collections
Point to elements
Setup
Step 1: add the repository
In your project’s root build.gradle.kts, append this repository to your list:
allprojects {
repositories {
mavenCentral()
}
}
Step 2: add the library
Add the dependencies into the project’s build.gradle.kts (change $arrowVersion to a specific version, or define the corresponding property in gradle.properties):
dependencies {
implementation("io.arrow-kt:arrow-optics:$arrowVersion")
}
If you are using more than one Arrow dependency, you can avoid specifying the same version over and over by using a BOM file:
dependencies {
implementation(platform("io.arrow-kt:arrow-stack:$arrowVersion"))
implementation("io.arrow-kt:arrow-core")
implementation("io.arrow-kt:arrow-optics")
...
}
Step 3: add the plug-in (optional)
To get the most of Arrow Optics you can add out Kotlin plug-in to your build, which takes care of generating optics for your data types.
plugins {
id("com.google.devtools.ksp") version "1.6.10-1.0.4"
}
dependencies {
ksp("io.arrow-kt:arrow-optics-ksp-plugin:$arrowVersion")
}
If you are using IntelliJ as your IDE of choice, you also need to add some new paths as sources to make it aware of the generated sources.
Now you are ready to learn about the Optics DSL!
Step 1: add the repository
In your project’s root build.gradle, append this repository to your list:
allprojects {
repositories {
mavenCentral()
}
}
Step 2: add the library
Add the dependencies into the project’s build.gradle:
def arrow_version = "1.0.1"
dependencies {
implementation "io.arrow-kt:arrow-optics:$arrow_version"
}
If you are using more than one Arrow dependency, you can avoid specifying the same version over and over by using a BOM file:
def arrow_version = "1.0.1"
dependencies {
implementation platform("io.arrow-kt:arrow-stack:$arrow_version")
implementation "io.arrow-kt:arrow-core"
implementation "io.arrow-kt:arrow-optics"
...
}
Step 3: add the plug-in (optional)
To get the most of Arrow Optics you can add out Kotlin plug-in to your build, which takes care of generating optics for your data types.
plugins {
id "com.google.devtools.ksp" version "1.6.10-1.0.4"
}
dependencies {
ksp "io.arrow-kt:arrow-optics-ksp-plugin:$arrow_version"
}
Now you are ready to learn about the Optics DSL!