Today’s Scala 3 Installation: My Complete Summary

🎯 Executive Summary

Today I successfully installed Scala 3.8.4 on my Debian system using Coursier, the official Scala installer. I ran into some PATH issues along the way, but I resolved them by manually adding the correct Coursier binary directory to my ~/.bashrc. After that, I validated everything by testing 18+ Scala 3 features right in the REPL. Here’s my full journey.

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📋 My Installation Timeline

Phase 1: Initial Attempt

• What I tried: scala -version
• What happened: bash: scala: command not found
• Why: No Scala or Coursier installed on my system yet

Phase 2: Downloading Coursier

• What I ran:bashcurl -fL “https://github.com/coursier/coursier/releases/latest/download/cs-x86_64-pc-linux.gz” | gzip -d > cs chmod +x cs
• Result: ✅ Downloaded successfully, made it executable

Phase 3: Running Coursier Setup

• What I ran: ./cs setup
• What happened:
  • Detected my JVM at /usr/lib/jvm/java-26-amazon-corretto
  • Asked if I wanted to add ~/.local/share/coursier/bin to PATH
  • I answered y (yes)
• Tools installed: ammonite, cs, coursier, scala, scalac, scala-cli, sbt, sbtn, scalafmt

Phase 4: Fixing the PATH Issue

• The problem: Even after setup, scala wasn’t recognized
• The fix: I manually added the path to my ~/.bashrcbashecho ‘export PATH=”$HOME/.local/share/coursier/bin:$PATH”‘ >> ~/.bashrc source ~/.bashrc
• Why: The setup script added it to ~/.profile, but I was using ~/.bashrc

Phase 5: Verification

• What I ran: scala -version
• Output:textScala code runner version: 1.14.0 Scala version (default): 3.8.4
• Result: ✅ Finally working!

Phase 6: REPL Testing

I spent time in the REPL testing all the key Scala 3 features. Everything worked beautifully (aside from some harmless Java warnings).

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💻 My Final Working Setup

Component	Version	Status
Scala	3.8.4	✅ Installed
JVM	26.0.2.1 (Amazon Corretto)	✅ Detected
Coursier	Latest	✅ Installed
sbt	Latest	✅ Installed
Scala CLI	Latest	✅ Installed
scalafmt	Latest	✅ Installed
Ammonite	Latest	✅ Installed
OS	Debian	✅ Compatible

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🚀 My Recommended Way Forward

What I’m Doing Next

1. Creating My First Project

bash

# Using sbt template (my preferred approach)
sbt new scala/scala3.g8
cd your-project-name
sbt run

2. Setting Up My IDE

VS Code with Metals (my recommendation):

• Install VS Code
• Install the Metals extension
• Open my project folder

Alternative: IntelliJ IDEA:

• Download IntelliJ IDEA Community Edition
• Install Scala plugin
• Import the sbt project

3. My Learning Routine

bash

# Daily practice - 15-20 minutes in REPL
scala          # Start the REPL
:load script.scala  # Load and test my scripts
:quit          # Exit when done

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🏷️ My Scala 3 Quick Reference

Category: Modern JVM Language

Tags: Functional Programming Object-Oriented JVM Type-Safe Multi-Paradigm Scala 3 Dotty

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📸 My Favorite Code Snippets

scala

// Scala 3 Highlights - What I Learned Today
// ===========================================

// 1. Enums (Algebraic Data Types) - Much cleaner than Scala 2!
enum Color:
  case Red, Green, Blue
  case Custom(hex: String)

// 2. Extension Methods - Finally! No more implicit classes!
extension (n: Int)
  def squared: Int = n * n
  def isEven: Boolean = n % 2 == 0

// 3. Union Types - This blew my mind!
def process(x: Int | String): String = x match
  case i: Int => s"Number: $i"
  case s: String => s"Text: $s"

// 4. Context Abstractions - Cleaner than implicits
trait Show[T]:
  extension (t: T) def show: String

given Show[Int] with
  extension (i: Int) def show: String = s"Int($i)"

// 5. Intersection Types - Like trait mixing on steroids
trait Flyable:
  def fly(): String = "Flying!"

trait Swimmable:
  def swim(): String = "Swimming!"

class Duck extends Flyable, Swimmable

// 6. Functional Collections - Where Scala shines
val nums = (1 to 10).toList
val evens = nums.filter(_ % 2 == 0)
val squares = nums.map(_.squared)
val total = nums.foldLeft(0)(_ + _)

// 7. Pattern Matching - So powerful!
def describe(c: Color): String = c match
  case Color.Red => "Stop!"
  case Color.Green => "Go!"
  case Color.Blue => "Relax"
  case Color.Custom(hex) => s"Custom: $hex"

// My test runs:
println(5.squared)           // 25 - works!
println(process(42))          // Number: 42
println(describe(Color.Red)) // Stop!
println(Duck().fly())         // Flying!

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📚 My Learning Roadmap

Week 1: The Basics

• □ Basic syntax and expressions
• □ Functions and methods
• □ Collections (List, Map, Option)
• □ Pattern matching
• □ Case classes

Week 2: Scala 3 Features

• □ Enums and ADTs
• □ Extension methods (my new favorite!)
• □ Given/Using (contextual abstractions)
• □ Union/Intersection types
• □ Opaque types (privacy without overhead)

Week 3: Functional Programming

• □ Immutability and pure functions
• □ Higher-order functions
• □ Type classes
• □ Monads (Option, Either, Try)
• □ For-comprehensions

Week 4: Building Projects

• □ sbt build configuration
• □ Testing with ScalaTest
• □ Error handling properly
• □ Basic CLI application
• □ Working with files

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🔧 My Handy Commands Reference

bash

# Environment Commands
scala -version        # Check my Scala version
scalac -version       # Check compiler version
cs list               # List all my installed tools
cs install scala      # Install/update Scala
sbt --version         # Check sbt version

# REPL Commands
scala                 # Start REPL
:help                 # Show all REPL commands
:quit                 # Exit REPL
:type <expr>          # Show expression type
:load <file>          # Load a Scala file

# Project Commands
sbt new scala/scala3.g8  # Create a new project
sbt compile               # Compile my project
sbt test                  # Run my tests
sbt run                   # Run my main class
sbt package               # Create a JAR file

# Scala CLI
scala-cli run file.scala  # Run a script
scala-cli repl            # Start REPL
scala-cli compile file.scala  # Compile a file

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✅ What I Accomplished Today

• ☑ Installed Coursier on my Debian system
• ☑ Successfully installed Scala 3.8.4
• ☑ Configured PATH for permanent access
• ☑ Verified installation with scala -version
• ☑ Tested Scala REPL
• ☑ Ran basic operations in REPL
• ☑ Explored Enums
• ☑ Tested Extension Methods
• ☑ Implemented Given/Using (type classes)
• ☑ Tried Union & Intersection types
• ☑ Verified sbt installation
• ☑ Validated Scala CLI installation

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📊 My System Status

text

✅ Scala 3.8.4  ── Installed and working
✅ Coursier      ── Package manager ready
✅ sbt           ── Build tool ready
✅ Scala CLI     ── Scripting ready
✅ JVM 26        ── Java runtime ready
✅ REPL          ── Interactive playground active
✅ PATH          ── Permanently configured
✅ .bashrc       ── Updated with Scala path

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🎉 My Final Verdict

Status: ✅ Production-Ready!

My Debian system is now fully equipped with a working Scala 3 development environment. All tools are installed, PATH is correctly configured, and I’ve already tested the REPL with major language features.

My Next Action: Creating my first project with sbt new scala/scala3.g8 and starting to build something!

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Questions I Still Have? I’ll keep this chat handy for:

• Project setup guidance
• Learning specific features
• Troubleshooting any new issues
• Best practices advice
• Library recommendations

Time to start coding with Scala 3! 🚀