What is a Scala cheat sheet?

A Scala cheat sheet is a quick reference guide containing the most commonly used syntax, functions, and patterns in Scala. It helps developers quickly look up syntax without searching through documentation.

How do I learn Scala quickly?

Start with the basics: variables, control flow, and functions. Use this cheat sheet as a reference while practicing. For faster learning, try DocuWriter.ai to automatically explain code and generate documentation as you learn.

What are the most important Scala concepts?

Key Scala concepts include variables and data types, control flow (if/else, loops), functions, error handling, and working with data structures like arrays and objects/dictionaries.

How can I document my Scala code?

Use inline comments for complex logic, docstrings for functions and classes, and README files for projects. DocuWriter.ai can automatically generate professional documentation from your Scala code using AI.

Scala Cheat Sheet - Quick Reference Guide 2026

Getting Started

4 snippets

Your first steps with Scala basics

Hello World

@main def hello(): Unit =
  println("Hello, World!")

Comments

// Single line comment

/* Multi-line
   comment */

String Interpolation

val name = "Scala"
println(s"Hello, $name!")  // Hello, Scala!

User Input

import scala.io.StdIn
val input = StdIn.readLine("Enter: ")
println(s"You entered: $input")

Variables & Data Types

7 snippets

Store and manage data in Scala

Val (Immutable)

val name = "John"

Var (Mutable)

var count = 0

Type Annotation

val age: Int = 25

List

val nums = List(1, 2, 3)

Map

val ages = Map("John" -> 30, "Jane" -> 25)

Tuple

val pair = (1, "hello")

Option

val name: Option[String] = Some("John")

Operators

5 snippets

Symbols for calculations and comparisons

Arithmetic

5 + 3    // 8 (addition)
5 - 3    // 2 (subtraction)
5 * 3    // 15 (multiplication)
5 / 3    // 1 (integer division)
5 % 3    // 2 (modulus)

Comparison

5 == 3   // false (equal)
5 != 3   // true (not equal)
5 > 3    // true (greater)
5 < 3    // false (less)
5 >= 3   // true (greater or equal)
5 <= 3   // false (less or equal)

Logical

true && false  // false (AND)
true || false  // true (OR)
!true          // false (NOT)

Compound Assignment

var x = 5
x += 3   // x = 8
x -= 2   // x = 6
x *= 2   // x = 12
x /= 3   // x = 4

String Operators

"Hello" + " World"  // concatenation
"abc" * 3           // "abcabcabc"

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Loops

7 snippets

Repeat code efficiently with iterations

For Range

for (i <- 1 to 5) {
  println(i)  // 1, 2, 3, 4, 5
}

For Until

for (i <- 0 until 5) {
  println(i)  // 0, 1, 2, 3, 4
}

For Collection

val fruits = List("apple", "banana")
for (fruit <- fruits) {
  println(fruit)
}

For Yield

val doubled = for (n <- nums) yield n * 2

While

var i = 0
while (i < 5) {
  println(i)
  i += 1
}

Foreach

nums.foreach(n => println(n))
nums.foreach(println)  // shorthand

For with Guard

for (i <- 1 to 10 if i % 2 == 0) {
  println(i)  // 2, 4, 6, 8, 10
}

Control Flow

2 snippets

Direct program execution with conditions

If Expression

val max = if (a > b) a else b

Match

x match {
  case 1 => "one"
  case 2 | 3 => "two or three"
  case _ => "other"
}

Functions

5 snippets

Reusable blocks of code with lambdas

Def

def greet(name: String): String = {
  s"Hello, $name!"
}

Short Form

def add(a: Int, b: Int) = a + b

Default Param

def greet(name: String = "World") = s"Hello, $name!"

Lambda

val add = (a: Int, b: Int) => a + b

Currying

def add(a: Int)(b: Int) = a + b

Collections

6 snippets

Functional transformations on data

Map

nums.map(_ * 2)

Filter

nums.filter(_ > 0)

FlatMap

nums.flatMap(n => List(n, n * 2))

Reduce

nums.reduce(_ + _)

Fold

nums.foldLeft(0)(_ + _)

GroupBy

people.groupBy(_.city)

Classes & OOP

5 snippets

Define custom types and objects

Class

class Dog(val name: String) {
  def bark(): String = s"$name says woof!"
}

Case Class

case class Person(name: String, age: Int)

Object

object Singleton {
  def doSomething(): Unit = {}
}

Trait

trait Greetable {
  def greet(): String
}

With Trait

class Person extends Animal with Greetable

Pattern Matching

3 snippets

Powerful matching expressions

Case Class Match

person match {
  case Person(name, age) => s"$name is $age"
  case _ => "unknown"
}

Option Match

opt match {
  case Some(value) => value
  case None => "default"
}

Guard

x match {
  case n if n > 0 => "positive"
  case _ => "non-positive"
}

Scala Cheat Sheet

Getting Started

Hello World

Comments

String Interpolation

User Input

Variables & Data Types

Val (Immutable)

Var (Mutable)

Type Annotation

List

Map

Tuple

Option

Operators

Arithmetic

Comparison

Logical

Compound Assignment

String Operators

Loops

For Range

For Until

For Collection

For Yield

While

Foreach

For with Guard

Control Flow

If Expression

Match

Functions

Def

Short Form

Default Param

Lambda

Currying

Collections

Map

Filter

FlatMap

Reduce

Fold

GroupBy

Classes & OOP

Class

Case Class

Object

Trait

With Trait

Pattern Matching

Case Class Match

Option Match

Guard

More Cheat Sheets

Frequently asked questions

What is a Scala cheat sheet?

How do I learn Scala quickly?

What are the most important Scala concepts?

How can I document my Scala code?

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