Functional Ruby

Transcript

1. 為你⾃⼰學 系列單元
   ޒഒላӃ
   Functional Ruby
   

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2. ޒഒላӃ
   വᏐࣜఔࣜઃܭ
   'VODUJPOBM1SPHSBNNJOH '1
   
   

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3. ޒഒላӃ
   ೺ਞྻཫॴ༗తحᏐ
   ငҎ೭ޙฒܭࢉશ෦ݩૉ័࿨
   

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4. ޒഒላӃ
   +4
   // JavaScript
   
   
   const list = [1, 2, 3, 4, 5]
   
   
   const odd_numbers = []
   
   
   // 挑出奇數
   
   
   for (let i = 0; i < list.length; i++) {
   
   
   const el = list[i]
   
   
   if (el % 2 === 1) {
   
   
   odd_numbers.push(el)
   
   
   }
   
   
   }
   
   
   const triple_numbers = []
   
   
   // 乘 3 倍
   
   
   for (let i = 0; i < odd_numbers.length; i++) {
   
   
   triple_numbers.push(odd_numbers[i] * 3)
   
   
   }
   
   
   let total = 0
   
   
   // 計算總和
   
   
   for (let i = 0; i < triple_numbers.length; i++) {
   
   
   total += triple_numbers[i]
   
   
   }
   
   
   console.log(total) // 27
   

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5. ޒഒላӃ
   +4
   // JavaScript
   
   
   const list = [1, 2, 3, 4, 5]
   
   
   const result = list.filter(i => i % 2 === 1)
   
   
   .map(i => i * 3)
   
   
   .reduce((acc, cv) => acc + cv, 0)
   
   
   console.log(result) // 27
   

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6. ޒഒላӃ
   +4
   // JavaScript
   
   
   const list = [1, 2, 3, 4, 5]
   
   
   const oddOnly = (i) => i % 2 === 1
   
   
   const triple = (i) => i * 3
   
   
   const sum = (acc, cv) => acc + cv
   
   
   const result = list.filter(oddOnly)
   
   
   .map(triple)
   
   
   .reduce(sum, 0)
   
   
   console.log(result) // 27
   

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7. ޒഒላӃ
   ॄኄੋ'1ʁ
   

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8. ޒഒላӃ
   ఔࣜޠݴయൣ
   1SPHSBNNJOH1BSBEJHNT
   

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9. ޒഒላӃ
   ෺݅ಋ޲ఔࣜઃܭ
   0CKFDU0SJFOUFE1SPHSBNNJOH
   

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10. ޒഒላӃ
    ෧᧋៺ঝ
    &ODBQTVMBUJPO*OIFSJUBODF
    

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11. ޒഒላӃ
    വᏐࣜఔࣜઃܭ
    'VODUJPOBM1SPHSBNNJOH
    

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12. ޒഒላӃ
    വᏐ
    'VODUJPO
    

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13. ޒഒላӃ
    ॄኄੋവᏐʁ
    

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14. ޒഒላӃ
    f(x) = 3x + 2
    

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15. ޒഒላӃ
    വᏐ༌ೖ值ᢛ༌ग़值೭ؒత᮫܎
    

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16. ޒഒላӃ
    ७വᏐ
    1VSF'VODUJPO
    

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17. ޒഒላӃ
    1VSF'VODUJPO
    ༌ग़݁Ռ୞᪑༌ೖ值༗᮫
    

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18. ޒഒላӃ
    +4
    # 不純
    
    
    def one_weeks_later
    
    
    Time.now + 7.days
    
    
    end
    

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19. ޒഒላӃ
    +4
    # 比較純
    
    
    def one_weeks_later(current_time)
    
    
    current_time + 7.days
    
    
    end
    

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20. ޒഒላӃ
    1VSF'VODUJPO
    ෆ။଄੒㐫ଶվᏓ
    

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21. ޒഒላӃ
    ᔒ༗෭࡞༻
    /PTJEFFGGFDU
    

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22. ޒഒላӃ
    +4
    # 不純
    
    
    def add_book
    
    
    Book.create(title: '為你⾃⼰學 Ruby')
    
    
    end
    

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23. ޒഒላӃ
    +4
    # 不純
    
    
    def replace_element(arr, idx, value)
    
    
    arr[idx] = value
    
    
    arr
    
    
    end
    
    
    list = [1, 2, 3]
    
    
    result = replace_element(list, 0, "a")
    
    
    p result # ["a", 2, 3]
    
    
    p list # ???
    

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24. ޒഒላӃ
    +4
    # 比較純
    
    
    def replace_element(arr, idx, value)
    
    
    dup_arr = arr.dup
    
    
    dup_arr[idx] = value
    
    
    dup_arr
    
    
    end
    
    
    list = [1, 2, 3]
    
    
    result = replace_element(list, 0, "a")
    
    
    p result # ["a", 2, 3]
    
    
    p list # ???
    

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25. ޒഒላӃ
    ෆՄᏓੑ
    *NNVUBCJMJUZ
    

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26. ޒഒላӃ
    +4
    // JavaScript
    
    
    const list = [1, 2, 3]
    
    
    const otherList = list
    
    
    console.log(list) // [1, 2, 3]
    
    
    otherList[0] = "a"
    
    
    console.log(list) // ???
    

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27. ޒഒላӃ
    +4
    // Rust
    
    
    fn main() {
    
    
    let list = [1, 2, 3];
    
    
    list[0] = 100; // 預設是不能修改的
    
    
    println!("{:?}", list);
    
    
    }
    

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28. ޒഒላӃ
    +4
    # Elixir
    
    
    list = [1, 2, 3]
    
    
    list[0] = 100 # 預設是不可修改的
    

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29. ޒഒላӃ
    '1JO3VCZ
    

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30. ޒഒላӃ
    +4
    list = [1, 2, 3, 4, 5]
    
    
    double_list = list.map { |n| 2 * n }
    
    
    odd_numbers = list.filter { |n| n.odd? }
    
    
    p double_list # [2, 4, 6, 8, 10]
    
    
    p odd_numbers # [1, 3, 5]
    

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31. ޒഒላӃ
    3VCZฒෆࢉੋਅਖ਼త'1-BOHVBHF
    

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32. ޒഒላӃ
    വᏐੋҰ౳ެຽ
    'JSTU$MBTT$JUJ[FO
    

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33. ޒഒላӃ
    +4
    // JavaScript
    
    
    const list = [1, 2, 3, 4, 5]
    
    
    const oddOnly = (i) => i % 2 === 1
    
    
    const triple = (i) => i * 3
    
    
    const sum = (acc, cv) => acc + cv
    
    
    const result = list.filter(oddOnly)
    
    
    .map(triple)
    
    
    .reduce(sum, 0)
    
    
    console.log(result) // 27
    

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34. ޒഒላӃ
    3VCZॴ༗త౦੢౎ੋ෺݅
    &WFSZUIJOHJO3VCZJTBOPCKFDU
    

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35. ޒഒላӃ
    ୠଖመ༗ࠣ౦੢ฒෆੋ෺݅
    

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36. ޒഒላӃ
    ᩋํ๏ʮ෺݅Խʯ
    

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37. ޒഒላӃ
    +4
    # 把⽅法物件化
    
    
    def add(a, b)
    
    
    a + b
    
    
    end
    
    
    m1 = method(:add)
    
    
    m2 = Proc.new { |x, y| add(x, y) }
    
    
    m3 = -> (x, y) { add(x, y) }
    
    
    puts m1.call(1, 2) # 3
    
    
    puts m2.call(3, 4) # 7
    
    
    puts m3.call(5, 6) # 11
    

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38. ޒഒላӃ
    ෆՄᏓੑ
    *NNVUBCJMJUZ
    

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39. ޒഒላӃ
    +4
    # Data.define 是 Ruby 3.2 之後才加進來的新功能
    
    
    Location = Data.define(:x, :y)
    
    
    point = Location.new(0, 0)
    
    
    puts point.x, point.y
    
    
    point.x = 100 # 錯誤
    

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40. ޒഒላӃ
    ိᴍෳᯑత
    

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41. ޒഒላӃ
    ᐬཬԽ
    $VSSZJOH
    

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42. ޒഒላӃ
    ೺ݪຊधཁଟݸჩᏐతവᏐ
    ᫚׵੒Ұܥྻ୞ཁݸჩᏐతവᏐతաఔ
    

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43. ޒഒላӃ
    +4
    def add_numbers(a, b, c)
    
    
    a + b + c
    
    
    end
    
    
    # 柯⾥化
    
    
    curried_add = -> (x) {
    
    
    -> (y) {
    
    
    -> (z) {
    
    
    add_numbers(x, y, z)
    
    
    }
    
    
    }
    
    
    }
    

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44. ޒഒላӃ
    +4
    # 分開寫
    
    
    add_2 = curried_add.call(2)
    
    
    add_3 = add_2.call(3)
    
    
    result = add_3.call(5)
    
    
    puts result
    
    
    # 或串在⼀起寫
    
    
    puts curried_add.call(2).call(3).call(5)
    

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45. ޒഒላӃ
    +4
    def add_numbers(a, b, c)
    
    
    a + b + c
    
    
    end
    
    
    

    # 柯⾥化
    
    
    # curried_add = -> (x) {
    
    
    # -> (y) {
    
    
    # -> (z) {
    
    
    # add_numbers(x, y, z)
    
    
    # }
    
    
    # }
    
    
    # }
    
    
    # Ruby 內建的⽅法
    
    
    curried_add = method(:add_numbers).curry
    

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46. ޒഒላӃ
    ภവᏐ
    1BSUJBM'VODUJPOT
    

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47. ޒഒላӃ
    ෦份BQQMZݪ࢝വᏐɼઌݻఆവᏐత෦෼
    ჩᏐɼճၚ઀डႫᰨჩᏐత৽വᏐ
    

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48. ޒഒላӃ
    +4
    def add_numbers(a, b, c)
    
    
    a + b + c
    
    
    end
    
    
    # Partial Function
    
    
    # 先給 1 個參數
    
    
    add_2 = -> (i, j) { add_numbers(2, i, j) }
    
    
    # 剩下的 2 個參數之後再⼀次給⾜
    
    
    puts add_2.call(3, 5) # 10
    

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49. ޒഒላӃ
    +4
    def add_numbers(a, b, c)
    
    
    a + b + c
    
    
    end
    
    
    # Partial Function
    
    
    # 或是先給 2 個參數
    
    
    add_2_and_3 = -> (k) { add_numbers(2, 3, k) }
    
    
    # 最後 1 個參數之後再給
    
    
    puts add_2_and_3.call(5) # 10
    

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50. ޒഒላӃ
    +4
    def add_numbers(a, b, c)
    
    
    a + b + c
    
    
    end
    
    
    # 利⽤內建的 curry ⽅法
    
    
    partial_fn = method(:add_numbers).curry
    
    
    # 先給 1 個參數
    
    
    add_2 = partial_fn.call(2)
    
    
    # 剩下的參數之後再⼀次給⾜
    
    
    puts add_2.call(3, 5) # 10
    

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51. ޒഒላӃ
    വᏐ߹੒
    'VODUJPO$PNQPTJUJPO
    

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52. ޒഒላӃ
    ઌՃɼ࠶Ճഒɼ࠷ޙ࠶ฏํʂ
    

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53. ޒഒላӃ
    +4
    // JavaScript
    
    
    const add_one = (n) => n + 1
    
    
    const double = (n) => n * 2
    
    
    const square = (n) => n * n
    
    
    console.log(square(double(add_one(5)))) // 144
    

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54. ޒഒላӃ
    ؅ઢ
    1JQF
    

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55. ޒഒላӃ
    +4
    # Elixir
    
    
    add_one = fn x -> x + 1 end
    
    
    double = fn x -> x * 2 end
    
    
    square = fn x -> x * x end
    
    
    result = 5 |> add_one.()
    
    
    |> double.()
    
    
    |> square.()
    
    
    IO.inspect result # 144
    

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56. ޒഒላӃ
    3VCZᔒ༗Ṝኄํศత౦੢
    

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57. ޒഒላӃ
    +4
    add_one = -> (n) { n + 1 }
    
    
    double = -> (n) { n * 2 }
    
    
    square = -> (n) { n * n }
    
    
    # 先加 1，再加倍，最後再平⽅
    
    
    composed_fn = add_one.compose(double)
    
    
    .compose(square)
    
    
    puts composed_fn.call(5) # 144
    

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58. ޒഒላӃ
    +4
    add_one = -> (n) { n + 1 }
    
    
    double = -> (n) { n * 2 }
    
    
    square = -> (n) { n * n }
    
    
    # 先加 1，再加倍，最後再平⽅
    
    
    composed_fn = add_one >> double >> square
    
    
    puts composed_fn.call(5) # 144
    

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59. ޒഒላӃ
    ޻঎෰຿
    

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