Scala - Features

Quiz

Scala Programming Language comes bundled with a lot of unique features. We have segregated these features into three sections −

Scala high-level Programming Features
Scala low-level Programming Features
Scala Ecosystem Feature

Let's start this chapter with the high-level features of Scala.

High-Level Programming Features

Scala runs on browsers and JVM (Java Virtual Machine). Scala is used for server-side applications and can also be used in the browser with "scala.js" file format.

Scala is High-Level Programming Language

You need not to deal with low-level concepts, like memory management and pointers. You can write code at a very high level using lambda and higher-order functions. You need to focus only on What and How while writing code in Scala, this is a property of high-level language.

val numbers = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

// Using an imperative approach to filter even numbers
def filterEvenNumbersImperative(numbers: List[Int]): List[Int] = {
   val evenNumbers = new ListBuffer[Int]()
   for (num <- numbers) {
      if (num % 2 == 0) {
         evenNumbers += num
      }
   }
   evenNumbers.toList
}

val evenNumbersImperative = filterEvenNumbersImperative(numbers)

Compiler will perform step by step according to instructions in the code. We use lambda functions and high-order functions to find the result.

// Using a functional approach with higher-order functions and lambdas to filter even numbers
val evenNumbersFunctional = numbers.filter(num => num % 2 == 0)

This code is easier to read and maintain. It is also much more concise.

Scala has a Concise Syntax

Syntax of Scala codes are much easier. For example, for creating variables and types, it is much easy to write, like this −

val message: String = "Hello, Scala!"
val numbers: Array[Int] = Array(1, 2, 3, 4, 5)
val personInfo: (String, Int, String) = ("Alice", 30, "Engineer")

We can also use lambda functions and higher-order functions for code readability and concise code.

val numbers = List(1, 2, 3, 4, 5)
val sum = numbers.reduce((a, b) => a + b)   // long form
val shortSum = numbers.reduce(_ + _)        // short form
println(s"Sum: $sum")
println(s"Short Sum: $shortSum")

val fruits = List("apple", "banana", "cherry", "date")
fruits.foreach(fruit => println(fruit))   // long form
fruits.foreach(println)                   // short form

Similarly, we can define traits, classes and methods in clean and light syntax −

trait Shape {
   def area(): Double
}

trait Color {
   def getColor(): String
}

class Circle(radius: Double, color: String) extends Shape with Color {
   def area(): Double = math.Pi * radius * radius
   def getColor(): String = color
}

Since developers spend more time reading than writing code, so it is important to write concise and readable code.

Scala is a Statically-type Language but has a Dynamic Feel

This is because of type inference capabilities which make Scala as Dynamic, like Python and Ruby code.

val x = List(1, 2, 3, 4, 5)
val doubled = x.map(_ * 2)
val filtered = x.filter(_ % 2 == 0)
val sum = x.reduce(_ + _)

According to Heather Miller Scala is a strong and Statically-typed programming language. Here are benefits of Static typed language −

It catches errors early, i.e., compiler time.
It has good IDE support. With reliable code completion and easy, reliable refactoring.
You can refactor your code.
It is scalable and maintainable.
Strong typing reduces boilerplate code.

Scala has an Expressive Type System

Type system of Scala improves safety and coherence through −

Inferred types
Generic, Open and Type classes
Polymorphic methods
Intersection and union types
Variance annotations
Type bounds (upper and lower)
Type lambdas
Opaque type aliases
Match types
Extension methods
Multiversal equality
Context bounds and functions
Dependent and Polymorphic function types
Inner classes and abstract type members for safe programming abstractions.

Scala is a Functional Programming Language

Functional programming languages provide various features. Functions are like other values and can be passed like any other values. Various functions are supported like lambda functions and high-order functions. Here everything is like an expression.

There are various mutable and immutable collections in the standard library. But Functional methods are not mutable and they only return updated copies.

Scala is an Object-Oriented Programming Language

In object-oriented type language, values are instances of class and operators are methods. In Scala, all types inherit from a top-level class, i.e., `Any` and `AnyVal` for value types like Int. AnyRef for reference types.

No distinction between primitives and boxed types. Boxing/unboxing is transparent to users.

Scala Supports FP/OOP Fusion

Scala supports FP (functional programming) and OOP (object-oriented programming) is typed setting. For example, functions for logic and Objects for modularity.

Scala Introduced Clear Term Inference

It is in Scala 3. It creates a term from a given type. There are context parameters which lead to inferred arguments. This is useful for type classes, context, dependencies etc.

Scala is used for Client/Server System

Scala code can run in the browser and on the JVM (Java Virtual Machine). JVM provides security, performance, memory management, portability etc.

Scala has Seamless Java Interaction

You can use Java classes and Java libraries in your Scala application and vice-versa is also correct. Libraries like Akka and Play Framework work in both languages. It is easy to use Java classes like BufferedReader.

import java.io.*;

String filename = "example.txt";
try (BufferedReader br = new BufferedReader(new FileReader(filename))) {
   String line;
   while ((line = br.readLine()) != null) {
      // Process the line here
   }
} catch (IOException e) {
   e.printStackTrace();
}

Java collections are used in Scala with simple conversion.

import scala.jdk.CollectionConverters._

val scalaList: Seq[Integer] = JavaClass.getJavaList().asScala.toSeq

Scala has a Rich set of Libraries

Scala offers a wealth of libraries and frameworks −

Play Framework is used for scalable web applications.
Lagom is used for microservices and legacy system transformation.
Apache Spark is used for big data analytics.

Numerous open source tools on Awesome Scala list. Scala.js is used for strong, JavaScript-like coding with React, jQuery, etc.

Low-Level Programming Features

The high-level features of Scala 2 and Scala 3 are almost the same. But in case of low-level, Scala 3 improves upon Scala 2 with the following features −

Concise algebraic data types (ADTs) using enums
More readable syntax and optional braces
Fewer symbols for better code clarity
Package objects replaced by simpler top-level definitions
Clearer grammar with explicit keywords
Extension methods for simplicity
Open modifier for controlled class modification
Multiversal equality to avoid nonsensical comparisons
Easier macro implementation
Union and intersection for flexible type modeling
Trait parameters for early initialization
Opaque type aliases for value class replacement
Export clauses for aggregation
Procedure and varargs syntax consistency
Annotations for method behavior and Java interoperability

Scala Ecosystem Features

Scala has a rich ecosystem which offers libraries and frameworks for various needs −

Web Development

Play Framework is used for scalable web apps.
Scalatra is used for high-performance web frameworks.
Finatra is used for Scala services.
Scala.js is used for type-safe front-end apps.
ScalaJs-React is used for Scala-friendly React.
Lagom is used for microservices and legacy systems.

Other Important Libraries

HTTP(S) Libraries are Akka-http, Finch, Sttp, Http4s, etc.
JSON Libraries are Argonaut, Circe, Json4s, Play-JSON, etc.
Serialization is ScalaPB.
Science and Data Analysis: Algebird, Spire, Squants etc.
Big Data:Apache Spark and Apache Flink.
AI and Machine Learning: BigDL (Distributed Deep Learning Framework) and TensorFlow Scala.
Functional Programming & FRP: FP: Cats, Zio and FRP: fs2, monix.
Build Tools: sbt, Gradle and Mill.

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