Created
June 19, 2023 17:08
-
-
Save prolativ/0fca0f4c1a36abca291837007ff80dd0 to your computer and use it in GitHub Desktop.
Constructing structural type in macro
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
//> using scala 3.3.0 | |
trait Sel extends Selectable: | |
def selectDynamic(name: String) = s"name: $name" | |
def applyDynamic(name: String)(args: Any*) = s"name: $name, args: $args" | |
object Sel: | |
type Subtype[T <: Sel] = T | |
import scala.quoted.* | |
transparent inline def makeSel: Sel = ${ makeSelImpl } | |
def makeSelImpl(using Quotes): Expr[Sel] = | |
import quotes.reflect.* | |
val tpe0 = TypeRepr.of[Sel] | |
val tpe1 = Refinement(tpe0, "field", TypeRepr.of[String]) | |
val tpe2 = Refinement(tpe1, "parameterless", ByNameType(TypeRepr.of[String])) | |
val tpe3 = Refinement(tpe2, "emptyParamList", MethodType(List())(_ => List(), _ => TypeRepr.of[String])) | |
val tpe4 = Refinement(tpe3, "singleParam", MethodType(List("arg1"))(_ => List(TypeRepr.of[Int]), _ => TypeRepr.of[String])) | |
val tpe5 = Refinement(tpe4, "curried", MethodType(List("arg1"))(_ => List(TypeRepr.of[Int]), _ => MethodType(List("arg2"))(_ => List(TypeRepr.of[Boolean]), _ => TypeRepr.of[String]))) | |
tpe5.asType match | |
case '[Sel.Subtype[t]] => '{ (new Sel {}).asInstanceOf[t] } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
@main def run() = | |
val sel = Sel.makeSel | |
println(sel.field) | |
println(sel.parameterless) | |
println(sel.emptyParamList()) | |
println(sel.singleParam(1)) | |
println(sel.curried(1)(true)) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment