Speech of Ike Kurghinyan, Senior Software Engineer at VChain LLC, at Ruby Meditation #26 Kyiv 16.02.2019 Next conference - http://www.rubymeditation.com/ «Is there one grand unifying rule to software engineering? Can so-called best practices be somehow derived from that unifying rule? This speech is a humble attempt to explore the subject and provide you with tools for your own explorations.» Announcements and conference materials https://www.fb.me/RubyMeditation News https://twitter.com/RubyMeditation Photos https://www.instagram.com/RubyMeditation The stream of Ruby conferences (not just ours) https://t.me/RubyMeditation * The channel of the organizers of the meetup https://t.me/incredevly

1. @dempfi
Best practices,
exploring!

2. @dempfi
Software Engineer at VChain
Ike Ku
!

3. @dempfi
Эээ..?

4. @dempfi
Первые годные планеры
188x Полет Уйтхэда
1901 Полет братьев Райт
1903
Математика крыла
191x Серийный тяжелый самолет
1917 Формула Глоэрта
1928

5. @dempfi
500,000 проданных копий
41 переизданий
Design Patterns: Elements of
Reusable Object-Oriented Software
Банда четырех
1994

6. @dempfi
Композиция

7. @dempfi
toLower: String !" String
log: Number !" Number
not: Boolean !" Boolean
length: String !" Number
isOdd: Number !" Boolean

8. @dempfi
String
Number
Boolean
length isOdd
toLower not
log

9. @dempfi
(length ◦ isOdd)(x) ""# isOdd(length(x))
length ◦ toLower ""# length ""# log ◦ length
String
Number
Boolean
length isOdd
length ◦ isOdd
toLower not
log

10. @dempfi
f ◦ (g ◦ h) ""# (f ◦ g) ◦ h
1ᴮ ◦ f ""# f ""# f ◦ 1ᴬ
A
B
C
f g
f ◦ g
1ᴬ 1&
1ᴮ

11. @dempfi
Don’t Repeat Youself

12. @dempfi
A
B
C
f
g
h
f: A !" B
g: A !" B
h: B !" C

13. @dempfi
A
B
C
f
g
h
h ◦ g
h ◦ f
h ◦ f ""# h ◦ gh ◦ f ""# h ◦ g

14. @dempfi
toLower: String !" String
toUpper: String !" String
length: String !" Number
length ◦ toUpper !!$ length ◦ toLower

15. @dempfi
https://hoogle.haskell.org/?hoogle=String->String

16. @dempfi
Keep It Simple, Stupid

17. @dempfi

18. @dempfi
A
B
D
C
E
f
g
h
k

19. @dempfi
A
B
D
C
E
f
g
h ◦ g
h
k

20. @dempfi
f: A !" B
g: A !" C
k: A !" D
h: C !" E
t: A !" E !!# h ◦ g

21. @dempfi
A
B
D
C
E
f
m
h
l

22. @dempfi
l ◦ (m ◦ f)
A
B
D
C
E
f
m
h
m ◦ f
l ◦ m
h ◦ m
h ◦ (m ◦ f)
l

23. @dempfi
f: A !" B
m: B !" C
l: C !" D
h: C !" E
g: A !" C !!# m ◦ f
k: A !" D !!# l ◦ g !!# l ◦ (m ◦ f)
t: A !" E !!# h ◦ g !!# h ◦ (m ◦ f)
u: B !" E !!# h ◦ m
j: B !" D !!# l ◦ m

24. @dempfi
id: a !" a

25. @dempfi
❤

26. @dempfi
Embrace abstraction

27. @dempfi
DRY + KISS

28. @dempfi
Separation of Concerns

29. @dempfi

30. @dempfi

31. @dempfi
!
Спасибо
за внимание!