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
   

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2. Re-learn
   
   
   Actions, Calculations and Data
   

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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
   

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4. Analogy
   for information system
   

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5. Usage
   • Thinking a problem before coding
   
   
   • Coding a solution
   
   
   • Reading existing code
   

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6. Use case - Pending Emails
   

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7. Reading code
   • Look for Actions because they need the most attention.
   
   
   • Find code smell without running code.
   

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8. Reading code
   

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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)
   

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10. Thinking a problem
    

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11. Coding a solution
    • Changeability: Actions > Calculations > Data.
    
    
    • Few Actions, more Calculations and Data.
    

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12. Coding a solution
    

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13. Solution
    

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14. Re-learn
    
    
    Strati
    f
    ied design
    

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15. Strati
    f
    ied design
    A technique for building
    software in layers.
    

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16. What is software design?
    "using one’s aesthetic sense to guide
    programming choices to improve the ease of
    coding, testing, and maintaining software"
    

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17. How strati
    f
    ied design help us
    to develop aesthetic senses
    • Straightforward implementation
    
    
    • Abstraction barrier
    
    
    • Minimal interface
    
    
    • Comfortable layers
    

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18. Straightforward implementation
    

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19. Call graph
    • Arrows represent function calls
    
    
    • Functions are in di
    ff
    erent layers
    Visualizing our function calls
    

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20. Straightforward
    call functions from similar layers of abstraction
    

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21. Straightforward
    all functions in a layer should serve the same purpose
    

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22. Problems
    may exist in three levels
    • Interaction between layers
    
    
    • Implementation of one layer
    
    
    • Implementation of one function
    

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23. Use call graph
    • Global zoom level
    
    
    • Layer zoom level
    
    
    • Function zoom level
    to
    f
    ind problems in di
    ff
    erent levels
    

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24. Call graph practice
    Pending Emails
    

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25. Q & A
    

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