Programação Funcional
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This document summarizes a presentation on functional programming. The presentation covers motivations for functional programming like simplicity and readability. It introduces functional programming concepts like pure functions, recursion, and laziness. Examples shown include filtering a stream lazily to find prime numbers, implementing natural numbers using classes, and partial function application. The presentation emphasizes that functional code is easy to understand, maintain, test and scale.
![> (defn soma3 [x] (+ x 3))
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-34-320.jpg)
![> (defn soma3 [x] (+ x 3))
> (map soma3 [2 4 6])
(5 7 9)
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-35-320.jpg)
![> (defn soma3 [x] (+ x 3))
> (map soma3 [2 4 6])
(5 7 9)
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-36-320.jpg)
![> (defn soma3 [x] (+ x 3))
> (map soma3 [2 4 6])
(5 7 9)
> (pmap soma3 [2 4 6])
(5 7 9)
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-37-320.jpg)
![Higher Order Function
pessoas = [{'nome': 'Adolfo', 'estado': 'MG'},
{'nome': 'Pedro', 'estado': 'RS'},
{'nome': 'Maria', 'estado': 'AC'}]
def por_estado(pessoa1, pessoa2):
return cmp(pessoa1['estado'], pessoa2['estado'])
>>> pprint.pprint(sorted(pessoas, cmp=por_estado))
[{'estado': 'AC', 'nome': 'Maria'},
{'estado': 'MG', 'nome': 'Adolfo'},
{'estado': 'RS', 'nome': 'Pedro'}]
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-38-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-51-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-52-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
val nats = from(0)
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-53-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
val nats = from(0)
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-54-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
val nats = from(0)
def sieve(s: Stream[Int]): Stream[Int] =
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-55-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
val nats = from(0)
def sieve(s: Stream[Int]): Stream[Int] =
s.head #:: sieve(s.tail filter (_ % s.head != 0))
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-56-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
val nats = from(0)
def sieve(s: Stream[Int]): Stream[Int] =
s.head #:: sieve(s.tail filter (_ % s.head != 0))
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-57-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
val nats = from(0)
def sieve(s: Stream[Int]): Stream[Int] =
s.head #:: sieve(s.tail filter (_ % s.head != 0))
val primes = sieve(from(2))
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-58-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
val nats = from(0)
def sieve(s: Stream[Int]): Stream[Int] =
s.head #:: sieve(s.tail filter (_ % s.head != 0))
val primes = sieve(from(2))
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-59-320.jpg)
![Laziness
def from(n: Int): Stream[Int] = n #:: from(n+1)
val nats = from(0)
def sieve(s: Stream[Int]): Stream[Int] =
s.head #:: sieve(s.tail filter (_ % s.head != 0))
val primes = sieve(from(2))
(primes take N).toList
Sunday, July 14, 13](https://image.slidesharecdn.com/programacao-funcional-130702222845-phpapp01/85/Programacao-Funcional-60-320.jpg)
Programação Funcional
- 1. Programação Funcional FISL 2013 Juarez Bochi λ Sunday, July 14, 13
- 2. Juarez Bochi Sunday, July 14, 13
- 3. Juarez Bochi Sunday, July 14, 13
- 4. Juarez Bochi Sunday, July 14, 13
- 5. Juarez Bochi Sunday, July 14, 13
- 6. Juarez Bochi Sunday, July 14, 13
- 7. Agenda • Motivação • Conceitos • Exemplos • Resumo Sunday, July 14, 13
- 9. Ler um arquivo, listar as palavras mais comuns em ordem decrescente. Sunday, July 14, 13
- 10. Ler um arquivo, listar as palavras mais comuns em ordem decrescente. Sunday, July 14, 13
- 11. Donald Knuth X Sunday, July 14, 13
- 12. Donald Knuth Doug McIlroy X Sunday, July 14, 13
- 13. Donald Knuth Doug McIlroy X 10+ páginas de Pascal/WEB Sunday, July 14, 13
- 14. Donald Knuth Doug McIlroy X 10+ páginas de Pascal/WEB 6 linhas de shell Sunday, July 14, 13
- 15. tr -cs A-Za-z 'n' | tr A-Z a-z | sort | uniq -c | sort -rn | sed ${1}q Sunday, July 14, 13
- 16. Sunday, July 14, 13
- 17. $ cat discurso.txt | tr -cs A-Za-z 'n' | tr A-Z a-z | sort | uniq -c | sort -rn | sed 40q 65 e 48 de 42 a 35 o 32 que 18 os 15 para 15 com 14 mais 13 nao 13 do 11 as 10 um 10 dos 10 da 9 das 8 ela 7 todos 7 se 7 pais 7 muito 6 ruas 6 brasil 5 violencia Sunday, July 14, 13
- 18. “Keep it simple, make it general, and make it intelligible.” Doug McIlroy Sunday, July 14, 13
- 19. “Keep it simple, make it general, and make it intelligible.” Doug McIlroy Sunday, July 14, 13
- 20. Conceitos Sunday, July 14, 13
- 21. Paradigmas • Imperativo • Lógico • Funcional • Orientado a Objetos Sunday, July 14, 13
- 22. Paradigma Imperativo Linguagem Computador Variáveis Mutáveis Endereço de memória Estruturas de controle (if-then-else, loop) Jumps Sunday, July 14, 13
- 23. “Can Programming Be Liberated from the von. Neumann Style?” John Backus - Turing Award Lecture Sunday, July 14, 13
- 24. Programação Funcional • Concentrar em teorias, não mutações • Minimizar mudança de estados • Sem estruturas de controle imperativas • Foco em funções Sunday, July 14, 13
- 25. “Programação Funcional é ortogonal à Orientação a Objetos” Sunday, July 14, 13
- 26. Elementos de Programação • Expressões Primitivas • Meios de Combinação • Meios de Abstração Sunday, July 14, 13
- 27. Exemplos Sunday, July 14, 13
- 28. First Class Functions Sunday, July 14, 13
- 29. First Class Functions Sunday, July 14, 13
- 30. Closure > var inc, dec; undefined > function contador() { ... var x = 0; ... inc = function() { return ++x; }; ... dec = function() { return --x; }; ... } undefined > contador(); undefined Sunday, July 14, 13
- 31. Closure > inc(); 1 > inc(); 2 > dec(); 1 > dec(); 0 > inc(); 1 > x ReferenceError: x is not defined Sunday, July 14, 13
- 32. > import Control.Applicative > let foo = fmap (+3) (+2) > foo 10 15 Sunday, July 14, 13
- 33. > import Control.Applicative > let foo = fmap (+3) (+2) > foo 10 15 Sunday, July 14, 13
- 35. > (defn soma3 [x] (+ x 3)) > (map soma3 [2 4 6]) (5 7 9) Sunday, July 14, 13
- 36. > (defn soma3 [x] (+ x 3)) > (map soma3 [2 4 6]) (5 7 9) Sunday, July 14, 13
- 37. > (defn soma3 [x] (+ x 3)) > (map soma3 [2 4 6]) (5 7 9) > (pmap soma3 [2 4 6]) (5 7 9) Sunday, July 14, 13
- 38. Higher Order Function pessoas = [{'nome': 'Adolfo', 'estado': 'MG'}, {'nome': 'Pedro', 'estado': 'RS'}, {'nome': 'Maria', 'estado': 'AC'}] def por_estado(pessoa1, pessoa2): return cmp(pessoa1['estado'], pessoa2['estado']) >>> pprint.pprint(sorted(pessoas, cmp=por_estado)) [{'estado': 'AC', 'nome': 'Maria'}, {'estado': 'MG', 'nome': 'Adolfo'}, {'estado': 'RS', 'nome': 'Pedro'}] Sunday, July 14, 13
- 39. Recursão Sunday, July 14, 13
- 40. Recursão (define (fib n) .. (if (< n 2) .. n .. (+ (fib (- n 1)) (fib (- n 2))))) (fib 10) => 55 Sunday, July 14, 13
- 41. Tail Call Optimization 1. fib(5) 2. fib(4) + fib(3) 3. (fib(3) + fib(2)) + (fib(2) + fib(1)) 4. ((fib(2) + fib(1)) + (fib(1) + fib(0))) + ((fibb(1) + fib(0)) + fib(1)) 5. (((fib(1) + fib(0)) + fib(1)) + (fib(1) + fib(0))) + ((fib(1) + fib(0)) + fib(1)) Sunday, July 14, 13
- 42. Tail Call Optimization (define (fib n) .. (letrec ((fib-aux (lambda (n a b) .. (if (= n 0) .. a .. (fib-aux (- n 1) b (+ a b)))))) .. (fib-aux n 0 1))) (fib 1000) => 4.346655768693743e+208 1. fib(5) 2. fib(4) + fib(3) 3. (fib(3) + fib(2)) + (fib(2) + fib(1)) 4. ((fib(2) + fib(1)) + (fib(1) + fib(0))) + ((fibb(1) + fib(0)) + fib(1)) 5. (((fib(1) + fib(0)) + fib(1)) + (fib(1) + fib(0))) + ((fib(1) + fib(0)) + fib(1)) Sunday, July 14, 13
- 43. Sunday, July 14, 13
- 44. Currying & Partials def to_tag(tag, texto): return "<{tag}>{texto}</{tag}>".format(tag=tag, texto=texto) Sunday, July 14, 13
- 45. Currying & Partials def partial(funcao, argumento): def fn(arg): return funcao(argumento, arg) return fn def to_tag(tag, texto): return "<{tag}>{texto}</{tag}>".format(tag=tag, texto=texto) Sunday, July 14, 13
- 46. Currying & Partials def partial(funcao, argumento): def fn(arg): return funcao(argumento, arg) return fn def to_tag(tag, texto): return "<{tag}>{texto}</{tag}>".format(tag=tag, texto=texto) negrito = partial(to_tag, 'b') italico = partial(to_tag, 'i') Sunday, July 14, 13
- 47. Currying & Partials def partial(funcao, argumento): def fn(arg): return funcao(argumento, arg) return fn def to_tag(tag, texto): return "<{tag}>{texto}</{tag}>".format(tag=tag, texto=texto) negrito = partial(to_tag, 'b') italico = partial(to_tag, 'i') >>> negrito(italico("Oi, FISL!")) "<b><i>Oi FISL!</i></b>" Sunday, July 14, 13
- 48. Currying & Partials def partial(funcao, argumento): def fn(arg): return funcao(argumento, arg) return fn def to_tag(tag, texto): return "<{tag}>{texto}</{tag}>".format(tag=tag, texto=texto) DSL!! negrito = partial(to_tag, 'b') italico = partial(to_tag, 'i') >>> negrito(italico("Oi, FISL!")) "<b><i>Oi FISL!</i></b>" Sunday, July 14, 13
- 49. Laziness Sunday, July 14, 13
- 50. Laziness Sunday, July 14, 13
- 51. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) Sunday, July 14, 13
- 52. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) Sunday, July 14, 13
- 53. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) val nats = from(0) Sunday, July 14, 13
- 54. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) val nats = from(0) Sunday, July 14, 13
- 55. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) val nats = from(0) def sieve(s: Stream[Int]): Stream[Int] = Sunday, July 14, 13
- 56. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) val nats = from(0) def sieve(s: Stream[Int]): Stream[Int] = s.head #:: sieve(s.tail filter (_ % s.head != 0)) Sunday, July 14, 13
- 57. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) val nats = from(0) def sieve(s: Stream[Int]): Stream[Int] = s.head #:: sieve(s.tail filter (_ % s.head != 0)) Sunday, July 14, 13
- 58. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) val nats = from(0) def sieve(s: Stream[Int]): Stream[Int] = s.head #:: sieve(s.tail filter (_ % s.head != 0)) val primes = sieve(from(2)) Sunday, July 14, 13
- 59. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) val nats = from(0) def sieve(s: Stream[Int]): Stream[Int] = s.head #:: sieve(s.tail filter (_ % s.head != 0)) val primes = sieve(from(2)) Sunday, July 14, 13
- 60. Laziness def from(n: Int): Stream[Int] = n #:: from(n+1) val nats = from(0) def sieve(s: Stream[Int]): Stream[Int] = s.head #:: sieve(s.tail filter (_ % s.head != 0)) val primes = sieve(from(2)) (primes take N).toList Sunday, July 14, 13
- 61. Data Abstraction class Zero(Natural): def __init__(self): pass def __repr__(self): return "0" def __add__(self, other): return other Sunday, July 14, 13
- 62. Data Abstraction class Zero(Natural): def __init__(self): pass def __repr__(self): return "0" def __add__(self, other): return other class Natural(object): def __init__(self, anterior): self.anterior = anterior def __repr__(self): return repr(self.anterior) + " + 1" def __add__(self, other): return self.anterior + other.sucessor() def sucessor(self): return Natural(anterior=self) Sunday, July 14, 13
- 63. Data Abstraction class Zero(Natural): def __init__(self): pass def __repr__(self): return "0" def __add__(self, other): return other class Natural(object): def __init__(self, anterior): self.anterior = anterior def __repr__(self): return repr(self.anterior) + " + 1" def __add__(self, other): return self.anterior + other.sucessor() def sucessor(self): return Natural(anterior=self)>>> zero = Zero() >>> um = zero.sucessor() >>> dois = um.sucessor() >>> um 0 + 1 >>> dois 0 + 1 + 1 >>> um + dois 0 + 1 + 1 + 1 Sunday, July 14, 13
- 64. Resumo Sunday, July 14, 13
- 65. Blub Paradox Sunday, July 14, 13
- 66. Resumo Código fácil de entender Sunday, July 14, 13
- 67. Resumo Código fácil de manter Sunday, July 14, 13
- 68. Resumo Código fácil de testar Sunday, July 14, 13
- 69. Resumo Código fácil de escalar Sunday, July 14, 13
- 71. Referências • http://www.leancrew.com/all-this/2011/12/more-shell-less-egg/ • http://onesixtythree.com/literate/literate2.pdf • http://mitpress.mit.edu/sicp/ • http://www.paulgraham.com/avg.html • https://www.coursera.org/course/progfun • http://www.slideshare.net/jbochi/programao-funcional-em-python • https://raw.github.com/richhickey/slides/master/simplicitymatters.pdf • http://pragprog.com/magazines/2013-01/functional-programming-basics • http://adit.io/posts/2013-04-17-functors,_applicatives,_and_monads_in_pictures.html • http://en.literateprograms.org/Fibonacci_numbers_(Scheme) • http://norvig.com/21-days.html • http://www.youtube.com/watch?v=3jg1AheF4n0 • http://www.flickr.com/photos/niceric/74977685/sizes/l/in/ Sunday, July 14, 13