Scala Expert

This covers the full Scala stack from functional programming fundamentals through Akka actors, streams, and HTTP. You get practical examples of case classes, pattern matching, Options and Either for null safety, and type classes with Cats. The reactive systems coverage is solid: typed actors with proper message protocols, backpressure handling in streams, and JSON APIs with Akka HTTP. Also includes Cats Effect and ZIO for pure functional IO. Use this when you need idiomatic Scala beyond basic syntax, especially if you're building concurrent or distributed systems. The examples assume you understand why immutability and referential transparency matter, so it won't convince you to go functional, but it will show you how.

skills.sh installs: 224
GitHub stars: 44
last updated: Aug 21, 2026

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Install

$ npx -y skills add personamanagmentlayer/pcl --skill scala-expert --agent claude-code

Installs into .claude/skills of the current project.

Files

Scala Expert

Expert guidance for Scala development, functional programming, Akka actors, and reactive systems.

Core Concepts

Scala Fundamentals

Immutability
Pattern matching
Case classes
Traits and mixins
Implicit conversions
For comprehensions

Functional Programming

Higher-order functions
Monads (Option, Either, Try)
Functors and Applicatives
Type classes
Pure functions
Referential transparency

Reactive Systems

Akka actors
Akka Streams
Akka HTTP
Play Framework
Cats Effect
ZIO

Scala Basics

// Case classes
case class User(id: String, name: String, email: String, age: Int)

// Pattern matching
def processUser(user: User): String = user match {
  case User(_, name, _, age) if age < 18 => s"$name is a minor"
  case User(_, name, _, age) if age >= 65 => s"$name is a senior"
  case User(_, name, _, _) => s"$name is an adult"
}

// Options instead of null
def findUser(id: String): Option[User] = {
  database.get(id)
}

val userName = findUser("123") match {
  case Some(user) => user.name
  case None => "Unknown"
}

// Or using map
val name = findUser("123").map(_.name).getOrElse("Unknown")

SKILL.md on GitHub