linyxus / dotty

Research platform for new language concepts and compiler technologies for Scala.

Dotty

• Documentation

Try it out

To try it in your project see also the Getting Started User Guide.

Building a Local Distribution

1. sbt dist/packArchive
2. Find the newly-built distributions in dist/target/

Code of Conduct

Dotty uses the Scala Code of Conduct for all communication and discussion. This includes both GitHub, Discord and other more direct lines of communication such as email.

How to Contribute

• Getting Started as Contributor
• Issues

License

Dotty is licensed under the Apache License Version 2.0

dotty's Issues

Structural GADT crashes the compiler

Minimized code

trait Expr { type T }
trait IntLit extends Expr { type T <: Int }
trait IntExpr extends Expr { type T = Int }

def foo[A](e: Expr { type T = A }) = e match {
  case _: IntLit =>
    val a: A = 0 // error
    val i: Int = ??? : A

  case _: Expr { type T <: Int } =>
    val a: A = 0 // error
    val i: Int = ??? : A // limitation // error

  case _: IntExpr =>
    val a: A = 0
    val i: Int = ??? : A

  case _: Expr { type T = Int } =>
    val a: A = 0
    val i: Int = ??? : A
}