ahoy-jon

2025-08-20 Original post.

2025-08-24 I'd like to refine the terminology used. The pattern demonstrated here is most accurately described as "polymorphism over effects, (using Higher-Kinded Types)".

It's important to distinguish this from other related concepts. Although it bears a strong resemblance to the Tagless Final pattern, this approach is distinct, and as a tight (not vendor free) integration with Kyo. Furthermore, please note that it is not "Effect Polymorphism," which is an alternate and less precise phrasing.

Thanks a lot to all of you for the valuable feedback!

---

kubukoz

runner.dialect = scala3
runner.dialectOverride.allowSignificantIndentation = false
# allows `if x then y`
runner.dialectOverride.allowQuietSyntax = true

ChristopherDavenport

import cats._
import cats.syntax.all._
import cats.data._
import cats.effect._
import cats.effect.syntax.all._
import cats.effect.std.Semaphore

trait Lock[F[_]]{ self => 
  def lock: F[Unit]
  def unlock: F[Unit]

odersky

Principled Meta Programming for Scala

This note outlines a principled way to meta-programming in Scala. It tries to combine the best ideas from LMS and Scala macros in a minimalistic design.

• LMS: Types matter. Inputs, outputs and transformations should all be statically typed.

• Macros: Quotations are ultimately more easy to deal with than implicit-based type-lifting

• LMS: Some of the most interesting and powerful applications of meta-programming