2000 katas later @cylicon

Talk about what I learned after implementing 2000 thousand katas, deliberate practice and how to receive impersonal feedback

Transcript

1. 2000 katas later https://goo.gl/JiNaIJ (slides) @nhpatt / Javier Gamarra
3. ἀναπάλη
4. a programming exercise which helps programmers hone their skills through practice and repetition
5. a programming exercise which helps programmers hone their skills through practice and repetition
6. poker hands roman numerals numeric sequences
7. a programming exercise which helps programmers hone their skills through practice and repetition
8. free of restrictions
9. “the practise of kata without learning to apply them in live situations is useless”
10. “the practise of kata without learning to apply them in live situations is useless” --Gichin Funakoshi
11. a programming exercise which helps programmers hone their skills through practice and repetition
12. practice, practice, practice
13. “merely doing your job every day doesn't qualify as real practice”
15. def apply_discount(item) @count[item] += 1 if (details = DISCOUNT[item]) if @count[item] % details[:quantity] == 0 @total -= details[:discount] end end end PRICE = { 'A' => 50, 'B' => 30, 'C' => 20, 'D' => 15 } DISCOUNT = { 'A' => {:quantity => 3, :discount => 20 }, 'B' => { :quantity => 2, :discount => 15 } }
18. deliberate practice
19. “continually tackling challenges that lie just beyond one's competence”
20. “Unless you're failing some of the time, you're probably not growing” -- Jeff Atwood
21. 4 stages of competence Dunning-Kruger effect
22. motivation becomes the real constraint on expertise.
23. Feedback!
25. “life-long period of deliberate effort”
26. I’ve done 2000 of them...
27. Why?
29. what have I learned?
30. languages
31. def create_array(n): res=[] i=1 while i<=n: res+=[i] return res Fix this infinite loop
32. def create_array(n): res=[] i=1 while i<=n: res+=[i] return res def create_array(n): res=[] i=1 while i<=n: res+=[i] i+= 1 return res Fix this infinite loop
33. Best practices def create_array(n): return range(1, n+1) Fix this infinite loop
34. Best practices def create_array(n): return range(1, n+1) Clever create_array= lambda n: range(1,n+1) Fix this infinite loop
35. better practices
36. 10 lines How do you rotate an array in Java?
37. 10 lines Collections.rotate(Arrays.asList(data), n); How do you rotate an array in Java?
38. def playerRankUp(pts): if pts >= 100: return ("Win!") else: return False How do you write conditionals?
39. def playerRankUp(pts): if pts >= 100: return ("Win!") else: return False def playerRankUp(pts): return "Win!" if pts >=100 else False How do you write conditionals?
40. how do you learn this? -- if you are from Valladolid
41. I am really a developer or just a good googler?
42. whiteboard coding
43. Length of the loop?
44. function loop_size(node){ var nodes = []; while(nodes.indexOf(node) == -1) { nodes.push(node); node = node.getNext(); } return nodes.length - (nodes.indexOf(node)); }
45. performance optimization
46. How many ways can you make the sum of a number? function sum(n, m = n) { if (n == 0) return 1; if (n < 0 || m == 0) return 0; let total = sum(n, m - 1) + sum(n - m, m); return total; }
47. // solution based on Euler decomposition with pentagonal numbers function sum(num) { var p = new Array p[0] = 1 var j = 0 var k = 0 var s = 0 if (num<=0){return 0} for (var i = 1; i<num+1;i++) { j=1 k=1 s=0 while (j>0){ j = i-(3*k*k+k)/2 if (j>=0) {s -= Math.pow(-1,k)*p[j]} j = i-(3*k*k-k)/2 if (j>=0) {s -= Math.pow(-1,k)*p[j]} k = k+1 } p[i] = s } return p[num] }
48. memoization?
49. How many ways can you make the sum of a number? function sum(n, m = n) { if (n == 0) return 1; if (n < 0 || m == 0) return 0; let total = sum(n, m - 1) + sum(n - m, m); return total; }
50. How many ways can you make the sum of a number? var memo = []; function sum(n, m = n) { if (n == 0) return 1; if (n < 0 || m == 0) return 0; if (memo[n] && memo[n][m]) return memo[n][m]; let total = sum(n, m - 1) + sum(n - m, m); if (!memo[n]) { memo[n] = []; } memo[n][m] = total; return total; }
51. def is_____(x): return pow(2, x - 1, x) == 1
52. def is_prime(x): return pow(2, x - 1, x) == 1
53. def is_prime(num): return num > 1 and not any(num % n == 0 for n in range(2,num))
54. If you do want to learn those things...
55. and in my work environment?
56. study group
57. we can’t stop talking about katas
58. talk freely with our work colleagues
59. share learning
60. in Japan your whole life is governed by all sorts of different kata
61. read someone else's code learn your favorite programming tools ask programming questions read about pioneers
63. do katas
64. do katas -- with me!
65. are you looking for a job? • HackerRank (hackerrank.com) • Codeeval (www.codeeval.com) • Kaggle (kaggle.com)
66. do you want to have learn having fun? • Codewars (codewars.com) • Exercism (exercism.io) • Solveet (solveet.com) (ES) • 12 meses 12 katas (github.com/12meses12katas) (ES) • Codefight (codefights.com)
67. do you want to play a videogame? • Checkio (checkio.org) • CodeCombat (codecombat.com) • Coding Game (codingame.com)
68. do you want to do math? • Project Euler (projecteuler.net)
69. some kata recommendations • Refactoring: Gilded Rose || Trip Service • Iterations: Lean Code (with facilitator) • You already know a lot: Calisthenics • You don’t want to be alone: Code Retreat • Architecture/Design: PacMan (any game kata) • Messy logic: Bowling, Poker Hands • Learn a language: Codewars
70. references • Kata is more than Karate • Benefits of code katas • Life code katas • "Old" Code Katas (codekatas.org) • Solid Gear (youtube.com)
71. questions?
72. Feedback? https://goo.gl/qwSi2q @nhpatt @liferay @cylicon_valley
73. 2000 katas later @nhpatt / Javier Gamarra