Hey, I’m trying to use arrow optics on Kotlin Multiplatform I have a Multiplatform module with JVM o...

# arrow

[Davide Giuseppe Farella]

Hey, I’m trying to use arrow optics on Kotlin Multiplatform
I have a Multiplatform module with JVM only, I’ve added the Ksp plugin and

kspCommonMainMetadata(libs.arrow.optics.ksp)
add("kspJvm", libs.arrow.optics.ksp)

then I’ve added

kotlin{ 
  sourceSets.all {
    kotlin.srcDir("build/generated/ksp/${this.name}/kotlin")
  }
}

and I see the code generated under
• generated/ksp/jvm/jvmMain/kotlin
• generated/ksp/metadata/commonMain/kotlin
But the generated code is not resolved
I believe I’m missing something in the setup (?)

[Davide Giuseppe Farella]

Running a ./gradlew build I see

> Task ⏱️playersdatakspCommonMainKotlinMetadata FAILED

e: [ksp] java.lang.NullPointerException: null cannot be cast to non-null type java.util.ArrayList<com.google.devtools.ksp.symbol.KSType>{ kotlin.collections.TypeAliasesKt.ArrayList<com.google.devtools.ksp.symbol.KSType> }

at arrow.optics.plugin.internals.ProcessorKt.targetsFromOpticsAnnotation(processor.kt:51)

[simon.vergauwen]

Hey @Davide Giuseppe Farella, this is a problem related KSP.

I’m not 100% sure what the best solution is for this issue. Is all your code inside commonMain? or do you have code inside jvmMain also?

Can you combine kspCommonMainMetadata with add("kspJvm" ? 🤔

[simon.vergauwen]

There seems to be a bug ticket related to regression from 1.6.x to 1.7.x, https://github.com/google/ksp/issues/1125

[Davide Giuseppe Farella]

Thank you, Simon, all my code is in commonMain .
What do you mean with

Can you combine kspCommonMainMetadata with add("kspJvm" ? 🤔

I thought that was the way to go, is the first time I’m trying KSP to be honest and I’ve read that ksp() is not suggested and will be removed

[Davide Giuseppe Farella]

Ref: https://kotlinlang.org/docs/ksp-multiplatform.html

[simon.vergauwen]

Yes, I think ksp specific commands are being removed. I am not sure what kspCommonMainMetadata does under the hood but it might be conflicting with add(".

Actually, on second look. You say that the generated code is not recognised but is being generated so that is not the problem.

I believe this is not correct.

kotlin{ 
  sourceSets.all {   
kotlin.srcDir("build/generated/ksp/${this.name}/kotlin")
  }
}

But not entirely sure how to link it for Kotlin MPP code. 🤔

Maybe:

kotlin{ 
  sourceSets.all {  
kotlin.srcDir("build/generated/ksp/jvm/jvmMain/kotlin")
     kotlin.srcDir("build/generated/ksp/metadata/commonMain/kotlin")
  }
}

[Davide Giuseppe Farella]

kspCommonMainMetadata is the “typed” alternative to add("kspCommonMainMetadata",
I will try your suggestion in a sec, thank you

[Davide Giuseppe Farella]

So I see that with both of them, I have a conflict, so I added only the JVM and seems to be fine on common code

kotlin{ 
  sourceSets.all { 
    kotlin.srcDir("build/generated/ksp/jvm/jvmMain/kotlin")
  }
}

About the code to be generated, it was my mistake, Arrows does generates under JVM only, the code under metadata was from Koin

[Davide Giuseppe Farella]

But wait, with your suggestion seems like they’re generated! Probably my setup was causing the crash at build-time!

[Davide Giuseppe Farella]

It works! This is awesome! arrow