Becoming a Functional Programmer - Harit Himanshu (Nomis Solutions)
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The document summarizes a presentation about becoming a functional programmer. It covers topics like immutability, pure vs impure functions, recursion, higher-order functions, and concurrency. The goal is to introduce functional programming concepts and vocabulary. The presentation includes an agenda, introductions, pre-requisites, topics to be covered, and next steps for learning more about functional programming in Scala.
![19
def printUserName(userId: Int, name: String) = {
println(s"The user[$userId] is called as $name")
}
Statement Example](https://image.slidesharecdn.com/techtrivenionbecomingafunctionalprogrammer-181203052721/85/Becoming-a-Functional-Programmer-Harit-Himanshu-Nomis-Solutions-19-320.jpg)
![36
def getFoodExpenses(ts: List[Transaction]): Double = {
val amounts = for (i <- ts.indices if ts(i).category == Food) yield ts(i).amount
amounts.sum
}
Creating Higher-Order Function
(Transaction) => BooleanTransaction => Boolean](https://image.slidesharecdn.com/techtrivenionbecomingafunctionalprogrammer-181203052721/85/Becoming-a-Functional-Programmer-Harit-Himanshu-Nomis-Solutions-36-320.jpg)
![37
def getFoodExpenses(ts: List[Transaction], pred: Transaction => Boolean): Double = {
// Implementation goes here
}
Creating Higher-Order Function
val amounts = for (i <- ts.indices if pred(ts(i))) yield ts(i).amount
amounts.sum](https://image.slidesharecdn.com/techtrivenionbecomingafunctionalprogrammer-181203052721/85/Becoming-a-Functional-Programmer-Harit-Himanshu-Nomis-Solutions-37-320.jpg)
![39
Map is a Transformation
val amounts: List[Double] = transactions.map((t: Transaction) => t.amount)
List.map => List
Set.map => Set](https://image.slidesharecdn.com/techtrivenionbecomingafunctionalprogrammer-181203052721/85/Becoming-a-Functional-Programmer-Harit-Himanshu-Nomis-Solutions-39-320.jpg)
![40
Filter is a Projection
val filtered: List[Transaction] = transactions.filter((t: Transaction) => t.debit == true)](https://image.slidesharecdn.com/techtrivenionbecomingafunctionalprogrammer-181203052721/85/Becoming-a-Functional-Programmer-Harit-Himanshu-Nomis-Solutions-40-320.jpg)
![46
Computing in Future
val resultInFuture: Future[Double] = Future {
// some asynchronous computation returning Double
}](https://image.slidesharecdn.com/techtrivenionbecomingafunctionalprogrammer-181203052721/85/Becoming-a-Functional-Programmer-Harit-Himanshu-Nomis-Solutions-46-320.jpg)
Becoming a Functional Programmer - Harit Himanshu (Nomis Solutions)
- 1. Becoming a Functional Programmer Presented By : Harit Himanshu
- 2. 2 Agenda About Harit Goal of the talk Pre-requisites Topics Next Steps Final Thoughts
- 3. 3 About Me harittweets Software Consultant Favorites Work Product Trave l moneybonsai.com
- 4. 4 Goal Vocabulary and Concepts Scala JavaScript Elm Haskell OCaml Java Languages
- 6. 6 ImmutabilityPure and Impure Functions Expressions and Statements Topics Functions
- 9. 9 Types of Functions Pure Impure
- 10. Pure function is a function where the return value is only determined by its input values, without observable side effects
- 11. 11 def grossMonthlySavings(grossMonthlyIncome: Double, expenses: Double) = grossMonthlyIncome - expenses grossMonthlySavings(10000.0, 4000.0) // 6000.0 grossMonthlySavings(10000.0, 4000.0) // 6000.0 grossMonthlySavings(10000.0, 4000.0) // 6000.0
- 13. 13 Pure vs Impure Functions Pure Impure
- 14. 14 Pure and Impure Functions Pure Impure
- 15. 15 Pure Function Benefits Easy to Test Reusable Parallelizable
- 16. An expression is something that yields a value
- 17. 17 val savings = income - expenses Expression Example
- 18. Statement is some code that does some action
- 19. 19 def printUserName(userId: Int, name: String) = { println(s"The user[$userId] is called as $name") } Statement Example
- 20. Immutability
- 21. 21 i = 10 j = 20 k = i + j // 25 Mathematics
- 22. 22 i = 10 j = 20 k = i + j // 30 i = 100 j = 90 k = i - j // 10 Imperative Programming
- 23. 23 Why Care About Immutability? Easier to Reason No accidental changes Parallelizable
- 24. 24 Immutability in Real World? Bank Transaction
- 25. 25 Variables in Scala var expenses = 4000.0 expenses = 5000.0 val income = 10000.0 // compilation error income = 9000.0 var (Mutable) val (Immutable)
- 26. 26 Mutability in var References Amazon Salaryt2 t1
- 27. 27 Mutability in var References Amazon Salaryt2 t1
- 28. 28 Immutability in val References Amazon Salaryt2 t1
- 29. 29 Immutable Reference Mutable Memory Amazont1
- 30. An expression is (said to be) referentially transparent if it can be replaced with its value without changing the program’s behavior.
- 31. Recursion
- 33. 33 Iteration Recursion Iteration vs Recursion
- 34. Tail recursion is a technique where the calculations are completed first, before passing in the results to the next recursive call
- 35. Higher-Order Functions are functions that take other functions as input or return functions as the result
- 36. 36 def getFoodExpenses(ts: List[Transaction]): Double = { val amounts = for (i <- ts.indices if ts(i).category == Food) yield ts(i).amount amounts.sum } Creating Higher-Order Function (Transaction) => BooleanTransaction => Boolean
- 37. 37 def getFoodExpenses(ts: List[Transaction], pred: Transaction => Boolean): Double = { // Implementation goes here } Creating Higher-Order Function val amounts = for (i <- ts.indices if pred(ts(i))) yield ts(i).amount amounts.sum
- 38. Express what needs to happen instead of how
- 39. 39 Map is a Transformation val amounts: List[Double] = transactions.map((t: Transaction) => t.amount) List.map => List Set.map => Set
- 40. 40 Filter is a Projection val filtered: List[Transaction] = transactions.filter((t: Transaction) => t.debit == true)
- 41. 41 Opening a Bank Account
- 42. 42 Opening another Bank Account Document Collection Counter Cash Counter
- 43. Currying is when a function that takes multiple arguments is divided into a series of functions that take part of the arguments
- 44. Concurrency
- 45. 45 Low-Level Concurrency Threads Locks Synchronization
- 46. 46 Computing in Future val resultInFuture: Future[Double] = Future { // some asynchronous computation returning Double }
- 47. 47 Next Steps
- 48. 48 Programming in Scala, 3rd Edition