A gentle introduction to functional programming

1. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING ENGINEERING MEETUP - 20TH APRIL 2020 Luca Di Stefano, Luca Ruzzola, Stefano Armenes
2. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING WHY?
3. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Pillars - referential transparency - function composition - no side-effects
4. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING No side-effects, really? - any operation that interacts with an external system - out-of-scope resources mutations - exceptions
5. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING ANYTHING IS A FUNCTION …or better, an expression!
6. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Referential transparency is all about expression Is this function referential transparent?
7. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Referential transparency is all about expression and what about this?
8. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Referential transparency is all about expression and what about this?
9. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Pure function A pure function is a function that, given the same input, always returns the same output without producing any side-effect.
10. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Pure function A pure function is a function that, given the same input, always returns the same output without producing any side-effect. Benefits - readability - parallelisation - memoization - more testable
11. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING We can compose two functions f and g when f domain is a subset of g domain. f ∘ g === f(g(x)) Composing functions
12. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Composing functions …but, we are missing somethings! We can compose two functions f and g when f domain is a subset of g domain. f ∘ g === f(g(x))
13. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Partial functions We want to live a world where every function is a total function Is this function total?
14. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Cool but, why my computation fails? Option[T]
15. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Either[L, R]
16. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Monads are your functional design patterns! Choose what you need IO List Option Either Set Future … Try
17. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING DEMO
18. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Questions?
19. A GENTLE INTRODUCTION TO FUNCTIONAL PROGRAMMING Thanks!