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01: Coding “Java way in Scala” Vs “Scala way in Scala”

Example #1: Read from a list & write to a list

Java Way in Scala


object ListToList extends App {
  
  val inputList = List("Java", "Scala", "Ruby")
  val outputList = scala.collection.mutable.ListBuffer[String]();
  
  for(item <- inputList) {
    outputList += item + " Programming"
  }
  
  println(outputList.toList)
}

object ListToList extends App {

val inputList = List("Java", "Scala", "Ruby")

val outputList = scala.

…

02: Coding Scala Way – Recursion & Iterator in FP

This extends Coding Scala Way – Part 1 Can you write the following code written in Java the Scala way? Java coding question on recursion and generics Q. Can you…

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03: Coding Scala Way – Lazy Eval

Example #6: Lazy initialization & evaluation of code Scala support “views”, which are collections that can be lazily evaluated. One use for views is when you need to traverse a…

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04: Coding Scala Way – Null checks with Option-Some-None

Example #10: Null checks with “Option-Some-None”

Nulls in Scala is a code smell, and a better way to handle null values is with an “Option“, which has 2 sub classes “Some” that has a value and a “None” that does not have a value. Instead of checking for “myVal !=…

05: Coding Scala Way – FP concepts

Example #13: Explain the concepts

Can you explain the Scala concepts applied in the following code snippets?


package com.myapp

object Test2 extends App {

  trait Wrapper[C[_]] {
    def aFunction[T,R](f: T => R): C[T] => C[R]
  }

  implicit object ListWrapper extends Wrapper[List] {
    //returns a function: so this is a higher order function
    override def aFunction[T,R](f: T => R): List[T] => List[R]  = { l =>
      println("taking T => R & returning List[T] => List[R]")
      l.map(f)

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06: Coding Scala Way – Reduce & Compose functions

Example #14: Reduce operations Given a list of functions as shown below, how will you go about applying all the functions in the list to each input number and sum…

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07: Coding Scala Way – Regular Expressions

Example #16: Regular Expression Regular expression (aka regex) to identify numbers in a string. Invoking “findFirstIn” and “findAll” functions of the “Regex” class. “[0-9]+”.r is a short form instead of…

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08: Coding Scala Way – Recursion & Higher Order Function

Example #20: n^th Fibonacci number

Q1 What is wrong with the following recursive approach to compute the n^th Fibonacci number?
A1 It “hangs” for the larger values of “n” like 50.


object RecursionVsIteration extends App {

  //1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144
  //find nth fibonacci number
  def fibNaive(n: Long): Long = {
    if (n <= 1) n
    else fibNaive(n - 1) + fibNaive(n - 2)
  }

  println(fibNaive(8))   // 8th number is 21
  println(fibNaive(12))  // 12th number is 144

  println(fibNaive(50))  //....hangs

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09: Coding Scala Way – Fibonacci Series

Example #22: Fibonacci series in Scala This extends determine the nth fibonacci number using Scala. In this let’s print the Fibonacci series of length n.


import scala.annotation.tailrec

object Fibonacci extends App {
  
   val zero = BigInt(0)
  
   def fibTail(n: Long): BigInt = {
     
    if (n <= 1) return 1 

    @tailrec
    def fibRecursion(a: BigInt, b: BigInt, n: BigInt): BigInt = {
      
      n match  {
        case `zero` => b  //wrap with "`" to match against a variable
        case _ => fibRecursion(b, a + b, n - 1)
      }    
    }
    
    fibRecursion(1, 1, n - 2)  
  }
   
  def fibSeries(n: Long) = (1L to n).map

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10: Coding Scala Way – groupBy, mapValues & identity

Java developers need to learn Coding Scala Way. Scala way of coding is quite different & you need to unlearn Java way of coding

Question: Given a list of numbers, how will you group the numbers by how many times they occur? for example output for “List(3, 3, 4, 5, 5, 5)” is List((3,2), (4,1), (5,3)).…

Blog Archives

01: Coding “Java way in Scala” Vs “Scala way in Scala”

Example #1: Read from a list & write to a list

02: Coding Scala Way – Recursion & Iterator in FP

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03: Coding Scala Way – Lazy Eval

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04: Coding Scala Way – Null checks with Option-Some-None

Example #10: Null checks with “Option-Some-None”

05: Coding Scala Way – FP concepts

Example #13: Explain the concepts

06: Coding Scala Way – Reduce & Compose functions

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07: Coding Scala Way – Regular Expressions

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08: Coding Scala Way – Recursion & Higher Order Function

Example #20: n^th Fibonacci number

09: Coding Scala Way – Fibonacci Series

10: Coding Scala Way – groupBy, mapValues & identity

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Blog Archives

Example #1: Read from a list & write to a list

Members Only Content

Members Only Content

Example #10: Null checks with “Option-Some-None”

Example #13: Explain the concepts

Members Only Content

Members Only Content

Example #20: nth Fibonacci number

800+ Java & Big Data Interview Q&As

200+ Java & Big Data Tutorials

Disclaimer

Example #20: n^th Fibonacci number