Functional programming - part 2

Applying the skill "Distinguish Actions, Calculations and Data".
See part 1 for some background knowledge.

Transcript

1. Functional programming James Su - 2022/05/27 Sur f ing in the changing world
2. Re-learn Actions, Calculations and Data
3. Glossary • Actions - Functions with side e ff ects • A ff ected by when and how many times they are called. • Calculations - functions without any side e ff ects • Given the same input, returns the same output. • Data - facts about events • Immutable in functional programming languages • Can be immutable in object-oriented programming languages
4. Analogy for information system
5. Usage • Thinking a problem before coding • Coding a solution • Reading existing code
6. Use case - Pending Emails
7. Reading code • Look for Actions because they need the most attention. • Find code smell without running code.
8. Reading code
9. Thinking a problem before coding • What data we will need to capture (Data) • What decisions we will need to make (Calculations) • Clarifying problems needs attention (Actions)
10. Thinking a problem
11. Coding a solution • Changeability: Actions > Calculations > Data. • Few Actions, more Calculations and Data.
12. Coding a solution
13. Solution
14. Re-learn Strati f ied design
15. Strati f ied design A technique for building software in layers.
16. What is software design? "using one’s aesthetic sense to guide programming choices to improve the ease of coding, testing, and maintaining software"
17. How strati f ied design help us to develop aesthetic senses • Straightforward implementation • Abstraction barrier • Minimal interface • Comfortable layers
18. Straightforward implementation
19. Call graph • Arrows represent function calls • Functions are in di ff erent layers Visualizing our function calls
20. Straightforward call functions from similar layers of abstraction
21. Straightforward all functions in a layer should serve the same purpose
22. Problems may exist in three levels • Interaction between layers • Implementation of one layer • Implementation of one function
23. Use call graph • Global zoom level • Layer zoom level • Function zoom level to f ind problems in di ff erent levels
24. Call graph practice Pending Emails
25. Q & A