Hi all! Could you please help me with using Optics...

# arrow

[Vitali Plagov]

Hi all! Could you please help me with using Optics? I’m trying to solve the issue with deep copy of data class.
My build.gradle has this:

plugins {
    id "org.jetbrains.kotlin.kapt" version "1.6.0"
}
dependencies {
    implementation "io.arrow-kt:arrow-core:1.0.1"
    implementation "io.arrow-kt:arrow-optics:1.0.1"
    kapt "io.arrow-kt:arrow-meta:1.0.1"
}

Then, all data classes are annotated with @optics and have a companion object

// showing a simple data class for brevity reasons
@optics
data class Mapping(
    val type: MappingType,
    val values: List<String>
) {
    companion object
}

Next, in my class when I’m trying to do this:

val updatedMapping = Mapping.

no fields (type or values) are shown after .
Am I missing something?

[simon.vergauwen]

Hey @Vitali Plagov,
That’s strange, sometimes IntelliJ will not pick up code from kapt and I had to apply idea gradle plugin.

Can you see the generated code in build/generated/kapt?

[Vitali Plagov]

Hi Simon,
No, there’s no kapt under build/generated
Do I have to run any gradle command or anything else once I added dependencies and annotations? I just reloaded all gradle projects and still nothing under that dir

[Vitali Plagov]

Just run the compileTestjava gradle task and it works

[Vitali Plagov]

That was unobvious (at least for me) 🙂
Thanks for the help!

[simon.vergauwen]

Oh, yes. That’s a bit of an oddity about Java annotation processing it runs and generate actual files on-the-fly but the code is only generated after the compiler has been invoked once.

[Vitali Plagov]

I guess, I don’t need to enable that setting in IDEA?

[simon.vergauwen]

I have never used this flag. It should not be necessary.

[Vitali Plagov]

Btw, Simon, is it still not possible to modify several fields at once with Lens? I found your answer on SO from Sep 2019. Is it still valid?

[simon.vergauwen]

That answer is still valid. We can consider moving this to Optics. @thanh has been making some improvements to Optics. Maybe we should open an issue on Github?

[Vitali Plagov]

Would be handy indeed to have an elegant API to modify several fields at once with Optics.

[thanh]

One note on Intelij not picking up generated code. I have to add something like this to build.gradle on one of my project:

sourceSets {
    debug {
        java.srcDir(file("build/generated/source/kapt/main"))
    }
}