Stack Overflow
Stack Overflow

Questions tagged [generic-derivation]

33 questions
33
votes
2 answers

How to decode an ADT with circe without disambiguating objects

Suppose I've got an ADT like this: sealed trait Event case class Foo(i: Int) extends Event case class Bar(s: String) extends Event case class Baz(c: Char) extends Event case class Qux(values: List[String]) extends Event The default generic…
Travis Brown
  • 138,631
  • 12
  • 375
  • 680
9
votes
1 answer

Generic derivation for ADTs in Scala with a custom representation

I'm paraphrasing a question from the circe Gitter channel here. Suppose I've got a Scala sealed trait hierarchy (or ADT) like this: sealed trait Item case class Cake(flavor: String, height: Int) extends Item case class Hat(shape: String, material:…
Travis Brown
  • 138,631
  • 12
  • 375
  • 680
8
votes
1 answer

Decoding JSON values in circe where the key is not known at compile time

Suppose I've been working with some JSON like this: { "id": 123, "name": "aubergine" } By decoding it into a Scala case class like this: case class Item(id: Long, name: String) This works just fine with circe's generic derivation: scala> import…
Travis Brown
  • 138,631
  • 12
  • 375
  • 680
7
votes
1 answer

Encoding ADT case classes with a discriminator, even when typed as the case class

Suppose I have a ADT in Scala: sealed trait Base case class Foo(i: Int) extends Base case class Baz(x: String) extends Base I want to encode values of this type into the JSON that looks like the following: { "Foo": { "i": 10000 }} { "Baz": { "x":…
Travis Brown
  • 138,631
  • 12
  • 375
  • 680
6
votes
2 answers

Type Class Derivation accessing default values

Is there a clean way to access the default values of a case class fields when performing type class derivation in Scala 3 using Mirrors? For example: case class Foo(s: String = "bar", i: Int, d: Double = Math.PI) Mirror.Product.MirroredElemLabels…
Simão Martins
  • 1,210
  • 11
  • 22
5
votes
0 answers

Type Class: Not using `asInstanceOf`, but still getting `ClassCastException`

Consider the following relatively simple code: import scala.deriving.Mirror trait TC[A]: def show: A object TC: inline def derived[A](using m: Mirror.ProductOf[A]): TC[A] = new TC[A]: override def show: A = val p: Product = new…
Koosha
  • 1,492
  • 7
  • 19
4
votes
1 answer

Transform a case class to another by unwrapping types in Scala 3

I have a enum that represents a container and two case classes: enum Container[+A]: case Value(value: A) case Default(default: A) def get: A = this match case Value(value) => value case Default(default) => default case class…
ColOfAbRiX
  • 1,039
  • 1
  • 13
  • 27
3
votes
1 answer

Scala 3 Method Too large when using Mirror

When I use Mirror of scala 3 to generate a typeclass list, the exception occurs. I know it's the hard limit of jvm of method size, but how can I circumvent this issue. ps: When delete some fields of Data class it works, but any other…
14sxlin
  • 76
  • 5
3
votes
1 answer

Blending Magnolia with Circe's trick for automatic derivation

I've got a typeclass and want to provide semi-automatic and automatic derivation to users. I have a working implementation based on Magnolia and it works really well. There's a trait providing definitions for Typeclass[A], combine[A] and…
Regis Kuckaertz
  • 991
  • 5
  • 14
3
votes
1 answer

Clarification on NN residual layer back-prop derivation

I've looked everywhere and can't find anything that explains the actual derivation of backprop for residual layers. Here's my best attempt and where I'm stuck. It is worth mentioning that the derivation that I'm hoping for is from a generic…
Jacob Statnekov
  • 245
  • 3
  • 12
3
votes
2 answers

C# - Call a derived base method in the derived context

Tried to search the web but found nothing so far so here my question: I want to index model-information via attributes on the different members. To do this i created a function in a base class that gathers all needed information when called. This…
Care.Inc
  • 31
  • 3
2
votes
1 answer

Tuples in Scala 3 Compiler Operations for Typeclass Derivation

Learning some of the new Scala 3 comppiletime operations and a bit confused about Tuple ( particularly using type matching on *: and EmptyTuple) import scala.compiletime.* imort cats.Show transparent inline def showForTuple[T <: Tuple]: Show[T] = …
Fabián Heredia Montiel
  • 1,687
  • 1
  • 16
  • 30
2
votes
1 answer

Cats auto derived with Seq

I want to define equality for some type that can be part of other objects or collections using cats/kitten. I don't want to have to define the equality for every other class. For example: import cats.Eq case class Foo(a: Int, bar: Bar) case class…
worldwideop
  • 51
  • 3
2
votes
1 answer

Is it possible to have a sub-trait inheirit a class parameter from another trait?

I am trying to DRY up my code a little bit. I am using Circe to do some decoding. I have several classes and all of them have the form of: import io.circe.derivation.deriveDecoder import io.circe.derivation.renaming.snakeCase import…
CL40
  • 579
  • 1
  • 5
  • 12
2
votes
0 answers

Narrow List[T] to a case class with elements of List[A <: T] and Option[B <: T]

I have the following classes; trait Part case class Part1() extends Part case class Part2() extends Part case class Part3(part1: Part1, part2: Part2) extends Part case class Part4(part1: Part1, part2: Option[Part2], part3: List[Part3]) extends…
Taha
  • 531
  • 4
  • 21
1
2 3