하스켈과 타입

하스켈과 타입에 대해 설명합니다.

2015년 4월 4일 하스켈 프로그래밍 다섯번째 모임
http://haskell.kr/meetup/2015-04-04/

Transcript

1. ೞझுҗ ఋੑ
   ഘ޹൞
   http://hongminhee.org/
   

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2. Data type
   • օܻ ॳ੉ח ߣ৉য: ੗ܐഋ
   • ୶ஏೡ ࣻ ੓٠, ੗ܐ(data)ܳ ࠙ܨ(type)ೞח Ѫ
   • Ӓۢ ࠙ܨೠ ੗ܐٜ਷ যڌѱ ࢤӟ Ѫੌө?
   

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3. Value
   • օܻ ॳ੉ח ߣ৉য: ч
   • য٥оী ੸ഃࢲ ա઺ী ੍൧ ࣻ ੓׮
   • ੉ଃীࢲ ੷ଃਵ۽ ੹೧઴ ࣻ ੓׮
   

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4. Value
   • օܻ ॳ੉ח ߣ৉য: ч
   • ݫݽܻա ٣झ௼ী ੷੢ೞҊ ա઺ী ৌযࠅ ࣻ ੓׮
   • ֎౟ਕ௼ܳ ా೧ ੹࣠ؼ ࣻ ੓׮
   

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5. Value
   • օܻ ॳ੉ח ߣ৉য: ч
   • ੉ܴ૑য૕ ࣻب ੓Ҋ, ੉ܴ੉ যڃ чਸ ڷೞח૑ب ঌ ࣻ ੓׮
   • ೣࣻ ੋ੗۽ ٜযт ࣻب ੓Ҋ, ೣࣻ۽ࠗఠ աৢ ࣻب ੓׮
   

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6. ч
   > let factorial n = product [1..n]
   > let x = 10
   > factorial x
   3628800
   

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7. ੉ܴ૑য૕ ࣻ ੓׮
   > let factorial n = product [1..n]
   > let x = 10
   > factorial x
   3628800
   

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8. ੉ܴ੄ ڷਸ ঌ ࣻ ੓׮
   > let factorial n = product [1..n]
   > let x = 10
   > factorial x
   3628800
   

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9. ೣࣻ ੋ੗۽ ٜযт ࣻ ੓׮
   > let factorial n = product [1..n]
   > let x = 10
   > factorial x
   3628800
   

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10. ೣࣻ۽ࠗఠ աৢ ࣻ ੓׮
    > let factorial n = product [1..n]
    > let x = 10
    > factorial x
    3628800
    

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11. ч੄ ࢿ૕
    • чٜ਷ ੷݃׮ ةౠೠ ࢿ૕੉ ੓׮
    • 1 ׮਺਷? 2. Ӓۢ 2 ׮਺਷? 3.
    • ['a', 'b', 'c']੄ ӡ੉ח? 3.
    • [] ׮਺਷? ݾ۾ೠప ‘׮਺’੉ۆ ަө?
    • 1੄ ӡ੉ח? ੿ࣻೠప ‘ӡ੉’ۆ ަө?
    

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12. ч੄ ࢿ૕
    > succ 1
    2
    > succ 2
    3
    > length ['a', 'b', 'c']
    3
    

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13. ч੄ ࢿ૕
    > succ ['a', 'b', 'c']
    :16:1:
    No instance for (Enum [Char]) arising from a
    use of ‘succ’
    In the expression: succ ['a', 'b', 'c']
    In an equation for ‘it’: it = succ ['a', 'b',
    'c']
    

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14. ч੄ ࢿ૕
    > length 1
    :17:8:
    No instance for (Num [a0]) arising from the
    literal ‘1’
    In the first argument of ‘length’, namely ‘1’
    In the expression: length 1
    In an equation for ‘it’: it = length 1
    

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15. ੗ܐഋ
    • чٜ਷ ੷݃׮ ةౠೠ ࢿ૕੉ ੓׮
    • Ӓ۞ա ࢿ૕੉ ൚ࢎೠ Ѫՙܻ ݽইࢲ ࠙ܨೡ ࣻ ੓׮
    • ‘׮਺’੉ ੓Ҋ, ف ч੉ ‘׮਺’ чٜ੉ ‘эਵݶ’ ف ч੉ ‘эҊ’,
    ‘؊ೡ ࣻ’ ੓Ҋ, ‘ࡓ ࣻ’ب ੓Ҋ… → ੿ࣻ ੗ܐഋ
    • 0ѐ ੉࢚੄ чਸ ‘ನೣ’ೡ ࣻ ੓Ҋ, ನೣػ чٜ ࢎ੉ী ‘ࣽࢲ’
    о ੓Ҋ… → ݾ۾ ੗ܐഋ
    

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16. ੗ܐഋ
    • ࠺तೠ ࢿ૕੄ чٜਸ ݽইفݶ ಞܻೞ׮
    • о۸, ؔࣅਸ ೡ ٸ ‘؊ೡ ࣻ ੓ח’ ࢿ૕੄ чٜ݅ ߉Ҋ र׮
    → ࣻ ੗ܐഋ݅ ߉ਵݶ ػ׮
    • о۸, іࣻܳ ҳೡ ٸ ‘чਸ ನೣೡ ࣻ ੓ח’ ࢿ૕੄ чٜ݅
    ߉Ҋ र׮ → ݾ۾ ੗ܐഋ݅ ߉ਵݶ ػ׮
    

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17. factorial਷ ੿ࣻ݅ ߉ח׮
    > factorial ['a', 'b', 'c']
    :26:1:
    No instance for (Num [Char]) arising from a
    use of ‘factorial’
    In the expression: factorial ['a', 'b', 'c']
    In an equation for ‘it’: it = factorial ['a',
    'b', 'c']
    

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18. ч੄ ੗ܐഋ
    (पઁח ੉ࠁ׮ ખ؊ ࠂ੟೤פ׮)
    > let factorial n =
    product ([1..n] :: [Integer]) :: Integer
    > let x = 10 :: Integer
    > factorial x :: Integer
    3628800 :: Integer
    

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19. ੗ܐഋ ঌইࠁӝ
    (पઁח ੉ࠁ׮ ખ؊ ࠂ੟೤פ׮)
    > :t x
    x :: Integer
    > :t factorial
    factorial :: Integer -> Integer
    

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20. ৈӝࢶ ׮ܖ૑ ঋח ׮਺ ઱ઁ
    • ؀ࣻ੸ ੗ܐഋ (algebraic data type)
    • Parametric polymorphism
    • ఋੑ௿ېझ (typeclass)
    • ⊥ (bottom)
    • ӝఋ ١١. ೞ૑݅ ށۄب ੌױ ೞझு ௏٬ द੘ оמ
    

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21. ࠗप೧ࢲ દ࣠೤פ׮
    bit.ly/haskell-kr-2015-04-04-type
    

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