Rudiments provides a small collection of tiny but useful utilities for everyday programming in Scala, and could be considered an enhanced 'predef'

Contingency is an experimental library for abstracting over error handling strategies. In particular, it gives developers a choice between throwing exceptions, returning errors in a variety of datatypes, and accumulating several validation-style ...

Typeclass interfaces to access user-defined Scala annotations

Utilities for working with exceptions in Scala

Versatile and composable lenses for Scala

Statically-checked string interpolation in Scala

UUIDs for Scala

Typesafe CSS in Scala

Statically-checked inline matching on regular expressions in Scala

Scala typeclasses for rendering different values as text for different audiences

soundness-all