rickynils/scalacheck

Property-based testing for Scala

milessabin/shapeless

Generic programming for Scala

scala-native/scala-native

Your favorite language gets closer to bare metal.

mpilquist/simulacrum

First class syntax support for type classes in Scala

scala/scala-parser-combinators

simple combinator-based parsing for Scala. formerly part of the Scala standard library, now a separate community-maintained module

typelevel/discipline

Flexible law checking for Scala

scala/scala-collection-compat

Scala 2.13 Collection Compatibility Library

typelevel/scalacheck

Property-based testing for Scala

ekrich/sconfig

Scala cross platform configuration library supporting HOCON

coursier/echo

Minimal JVM and scala-native echo command

scala-native/scala-native-loop

Extensible event loop and async-oriented IO for Scala Native; powered by libuv