Compatibility required for migration from Scala2 macro

Dotty
1

Hello,

Scala2 macro was experimental, so it may not be planned to support all features.
However, features used in many libraries have been lost, and some OSS are difficult to migrate.
And I am one of them.

Has the equivalent of Parsers been removed?

The Quasiquote and Parsers features were very efficient for building uncertain Trees.
Referencing unknown types at the time the Macro is expanded, and expanding variable length parameters are difficult in Scala3’s macro.

https://www.scala-lang.org/api/current/scala-reflect/scala/reflect/macros/Parsers.html

2

Those are use cases that we explicitly did not want to support since they cause language fragmentation, with many possible dialects supported by macros. I am sure there are good use cases
for this, but overall I believe allowing this would be detrimental to the language ecosystem as a whole.

2 Likes
3

That is very disappointing, but good to know that it will not be supported in the short term. Thank you.