mrdziuban

import magnolia.{CaseClass, Magnolia, SealedTrait}
import scala.language.experimental.macros

trait Csv[A] { def apply(a: A): Seq[String] }

trait LPCsv {
  type Typeclass[A] = Csv[A]

  def combine[A](ctx: CaseClass[Csv, A]): Csv[A] =
    a => ctx.parameters.foldLeft(List[String]())((acc, p) => acc ++ p.typeclass(p.dereference(a)))

mrdziuban

[error] error while loading Object, Missing dependency 'object scala in compiler mirror', required by /Library/Java/JavaVirtualMachines/jdk1.8.0_202.jdk/Contents/Home/jre/lib/rt.jar(java/lang/Object.class)
[error] ## Exception when compiling 5 sources to /my/thing/target/scala-2.12/classes
[error] object scala in compiler mirror not found.
[error] scala.reflect.internal.MissingRequirementError$.signal(MissingRequirementError.scala:24)
[error] scala.reflect.internal.MissingRequirementError$.notFound(MissingRequirementError.scala:25)
[error] scala.reflect.internal.Mirrors$RootsBase.$anonfun$getModuleOrClass$4(Mirrors.scala:61)
[error] scala.reflect.internal.Mirrors$RootsBase.getModuleOrClass(Mirrors.scala:61)
[error] scala.reflect.internal.Mirrors$RootsBase.getModuleOrClass(Mirrors.scala:73)
[error] scala.reflect.internal.Mirrors$RootsBase.getPackage(Mirrors.scala:179)
[error] scala.reflect.internal.Definitions$DefinitionsClass.ScalaPackage$lzycompute(Definitions.scala:196)

mrdziuban

"pool-11-thread-7" #160 prio=5 os_prio=31 cpu=70645.61ms elapsed=146.72s tid=0x0000000131d56800 nid=0x14303 runnable  [0x00000002b5737000]
   java.lang.Thread.State: RUNNABLE
	at dotty.tools.dotc.core.Types$VariantTraversal.stopBecauseStaticOrLocal(Types.scala:5532)
	at dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5649)
	at dotty.tools.dotc.core.TypeComparer$$anon$1.apply(TypeComparer.scala:266)
	at dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5655)
	at dotty.tools.dotc.core.TypeComparer$$anon$1.apply(TypeComparer.scala:266)
	at dotty.tools.dotc.core.Types$TypeMap.op$proxy17$1(Types.scala:5618)
	at dotty.tools.dotc.core.Types$TypeMap.mapArgs(Types.scala:5618)
	at dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5655)

mrdziuban

java.lang.AssertionError: assertion failed: invalid prefix ExprType(AppliedType(TypeRef(TermRef(ThisType(TypeRef(NoPrefix,module class <root>)),object scala),class ValueOf),List(TypeRef(NoPrefix,type L))))
  at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
  at dotty.tools.dotc.core.Types$NamedType.<init>(Types.scala:2186)
  at dotty.tools.dotc.core.Types$TypeRef.<init>(Types.scala:2799)
  at dotty.tools.dotc.core.Types$CachedTypeRef.<init>(Types.scala:2855)
  at dotty.tools.dotc.core.Uniques$NamedTypeUniques.newType$1(Uniques.scala:45)
  at dotty.tools.dotc.core.Uniques$NamedTypeUniques.linkedListLoop$1(Uniques.scala:56)
  at dotty.tools.dotc.core.Uniques$NamedTypeUniques.enterIfNew(Uniques.scala:62)
  at dotty.tools.dotc.core.Types$TypeRef$.apply(Types.scala:2914)
  at dotty.tools.dotc.core.Types$TypeRef$.apply(Types.scala:2920)

mrdziuban

java.lang.StackOverflowError while typechecking /path/to/file.scala
scala.runtime.Statics.anyHash(Statics.java:127)
scala.collection.immutable.HashMap.get(HashMap.scala:136)
dotty.tools.dotc.core.Contexts$Context.property(Contexts.scala:154)
dotty.tools.dotc.printing.PlainPrinter.limiter(PlainPrinter.scala:37)
dotty.tools.dotc.printing.PlainPrinter.controlled(PlainPrinter.scala:39)
dotty.tools.dotc.printing.RefinedPrinter.toText(RefinedPrinter.scala:307)
dotty.tools.dotc.core.Types$Type.toText(Types.scala:1911)
dotty.tools.dotc.printing.Printer.toTextLocal$$anonfun$1(Printer.scala:170)
dotty.tools.dotc.printing.Printer.atPrec(Printer.scala:43)

mrdziuban

import scala.annotation.MacroAnnotation
import scala.quoted.*

class autoGiven extends MacroAnnotation {
  final def transform(using Quotes)(tree: quotes.reflect.Definition): List[quotes.reflect.Definition] = {
    import quotes.reflect.*

    tree match {
      case ValDef(name, tpt, Some(rhs)) => rhs.asExpr match {
        case '{ $rhsExpr: t } =>

mrdziuban

java.lang.StackOverflowError
  at dotty.tools.dotc.core.Types$VariantTraversal.stopBecauseStaticOrLocal(Types.scala:5539)
  at dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5656)
  at dotty.tools.dotc.core.TypeComparer$$anon$1.apply(TypeComparer.scala:266)
  at dotty.tools.dotc.core.Types$TypeMap.op$proxy18$1(Types.scala:5658)
  at dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5658)
  at dotty.tools.dotc.core.TypeComparer$$anon$1.apply(TypeComparer.scala:266)
  at dotty.tools.dotc.core.Types$TypeMap.op$proxy17$1(Types.scala:5625)
  at dotty.tools.dotc.core.Types$TypeMap.mapArgs(Types.scala:5625)
  at dotty.tools.dotc.core.Types$TypeMap.mapOver(Types.scala:5662)

mrdziuban

case class Foo()
case class Bar(foo: Foo)

// fails because there is no `Decoder[Foo]`
io.circe.Decoder.derived[Bar]

mrdziuban

case class Foo()
case class Bar(foo: Foo)

// succeeds and automatically derives a `Decoder[Foo]`
io.circe.Decoder.derived[Bar]

mrdziuban

sealed trait Test1
object Test1 {
  case object Member extends Test1
}

sealed trait Test2
object Test2 {
  sealed trait SubTrait extends Test2
  case object Member extends SubTrait
}