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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)

…

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

…

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)).…

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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

Members Only Content

03: Coding Scala Way – Lazy Eval

Members Only Content

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

Prepare to go places

Disclaimer

Example #20: n^th Fibonacci number