Functional Programming Introduction
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Roberto Lopez has over 20 years of experience in IT, starting as a help desk technician and later founding his own consulting firm focused on Microsoft technologies. He is currently learning Haskell and Elm. Functional programming is a paradigm based on mathematical functions that treats functions as first-class citizens and avoids side effects. It emphasizes concepts like pure functions, immutability, recursion, and lazy evaluation. Functional programming can provide benefits like easier reasoning about programs and fewer bugs.
![FUNCTIONAL PROGRAMMING
WHAT IS IT?
Based on lambda calculus - Alonzo Church 1930s
Turing complete
了x.(x + 1) => 了x.(x + 1) 3 => [x := 3] => 3 + 1 => 4
Expressions, variables, and abstractions
Expressions = variables | abstractions
Abstractions = functions
9](https://image.slidesharecdn.com/functionalprogramming-191014151935/85/Functional-Programming-Introduction-9-320.jpg)
Functional Programming Introduction
- 1. I WROTE A FUNCTION, AM I A FUNCTIONAL PROGRAMMING
- 2. FUNCTIONAL PROGRAMMING DEVSPACE WOULD LIKE TO THANK OUR SPONSORS
- 3. FUNCTIONAL PROGRAMMING ROBERTO LOPEZ Over 20 Years in IT Started as a Help Desk technician 11 years ago started RHLopez Consulting, Inc. Primarily work with Microsoft .Net and .Net Core Application Development, Software Architecture, Systems Integration, Database Design, Report Writing Manufacturing, Financial, Management, Higher Education, E-commerce, Media Sectors Learning Haskell, Elm E-mail: roberto@rhlopez.com Twitter: @ralmlopez Phone: 615-604-0813
- 4. FUNCTIONAL PROGRAMMING MOTIVATION Teach to learn First conference talk Helping others through my experience
- 5. FUNCTIONAL PROGRAMMING Why should I care? What is it? Characteristics Learning Resources OVERVIEW
- 6. FUNCTIONAL PROGRAMMING WHY SHOULD I CARE? A different way of thinking / solving a problem Less typing (succint) Higher levels of abstraction Easier to reason about a program Less bugs - no nulls, sum types
- 7. FUNCTIONAL PROGRAMMING WHAT IS IT? Functional programming is so called because its fundamental operation is the application of functions to arguments John Hughes, Why Functional Programming Matters
- 8. FUNCTIONAL PROGRAMMING WHAT IS IT? Functional programming is a computer programming paradigm that relies on functions modeled on mathematical functions. The essence of functional programming is that programs are a combination of expressions. Haskel Programming from First Principles, Chris Allen and Julie Moronuki 8
- 9. FUNCTIONAL PROGRAMMING WHAT IS IT? Based on lambda calculus - Alonzo Church 1930s Turing complete 了x.(x + 1) => 了x.(x + 1) 3 => [x := 3] => 3 + 1 => 4 Expressions, variables, and abstractions Expressions = variables | abstractions Abstractions = functions 9
- 10. FUNCTIONAL PROGRAMMING CHARACTERISTICS Functions are First-Class, Higher-Order Pure Functions (No Side-Effects) Referential Transparency Immutability Currying Partial Application Recursion Lazy
- 11. FUNCTIONAL PROGRAMMING CHARACTERISTICS - FUNCTIONS FIRST-CLASS Functions treated as first-class variables Can be passed to functions as parameters Can be returned from functions Functions that take or return functions are called higher-order functions
- 12. FUNCTIONAL PROGRAMMING CHARACTERISTICS - PURE FUNCTIONS Functions only operate on the inputs given No side-effects 12
- 13. FUNCTIONAL PROGRAMMING CHARACTERISTICS - REFERENTIAL TRANSPARENCY Functions yield the same result for a given input
- 14. FUNCTIONAL PROGRAMMING CHARACTERISTICS - IMMUTABILITY Data is immutable, it cannot be changed once declared Functions return a copy of the data with the new changes 14
- 15. FUNCTIONAL PROGRAMMING CHARACTERISTICS - CURRYING Functions take one argument and return one result
- 16. FUNCTIONAL PROGRAMMING CHARACTERISTICS - PARTIAL APPLICATION Fix a number of arguments to a function to produce another function of smaller arity
- 17. FUNCTIONAL PROGRAMMING CHARACTERISTICS - RECURSION Heavily used and often the only way to iterate
- 18. FUNCTIONAL PROGRAMMING CHARACTERISTICS - LAZY Since functions are pure and have referential integrity they can be called at any time and yield the same result This makes it possible to delay computation until needed
- 19. FUNCTIONAL PROGRAMMING HASKELL TYPES No Nulls Sum Types I call it my billion-dollar mistake. It was the invention of the null reference in 1965. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years. Tony Hoare 19
- 20. FUNCTIONAL PROGRAMMING LEARNING Can be frustrating Pure functional vs hybrid languages Some pure languages: Haskell, Elm, Idris, PureScript .Net - F# Java - Clojure and Scala Erlang and Elixir Javascript Python
- 21. FUNCTIONAL PROGRAMMING RESOURCES Haskell Programming from first principles - Chris Allen and Julie Moronuki Programming Elm - Jeremy Fairbank Haskell Weekly Elm Town, Javascript to Elm Functional Geekery Lambda Cast
- 22. WHACK A BUG QUESTIONS? THANK YOU