하스켈과 타입

하스켈과 타입에 대해 설명합니다.

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

1. ೞझுҗ ఋੑ ഘ޹൞ http://hongminhee.org/
2. Data type • օܻ ॳ੉ח ߣ৉য: ੗ܐഋ • ୶ஏೡ ࣻ ੓٠, ੗ܐ(data)ܳ ࠙ܨ(type)ೞח Ѫ • Ӓۢ ࠙ܨೠ ੗ܐٜ਷ যڌѱ ࢤӟ Ѫੌө?
3. Value • օܻ ॳ੉ח ߣ৉য: ч • য٥оী ੸ഃࢲ ա઺ী ੍൧ ࣻ ੓׮ • ੉ଃীࢲ ੷ଃਵ۽ ੹೧઴ ࣻ ੓׮
4. Value • օܻ ॳ੉ח ߣ৉য: ч • ݫݽܻա ٣झ௼ী ੷੢ೞҊ ա઺ী ৌযࠅ ࣻ ੓׮ • ֎౟ਕ௼ܳ ా೧ ੹࣠ؼ ࣻ ੓׮
5. Value • օܻ ॳ੉ח ߣ৉য: ч • ੉ܴ૑য૕ ࣻب ੓Ҋ, ੉ܴ੉ যڃ чਸ ڷೞח૑ب ঌ ࣻ ੓׮ • ೣࣻ ੋ੗۽ ٜযт ࣻب ੓Ҋ, ೣࣻ۽ࠗఠ աৢ ࣻب ੓׮
6. ч > let factorial n = product [1..n] > let x = 10 > factorial x 3628800
7. ੉ܴ૑য૕ ࣻ ੓׮ > let factorial n = product [1..n] > let x = 10 > factorial x 3628800
8. ੉ܴ੄ ڷਸ ঌ ࣻ ੓׮ > let factorial n = product [1..n] > let x = 10 > factorial x 3628800
9. ೣࣻ ੋ੗۽ ٜযт ࣻ ੓׮ > let factorial n = product [1..n] > let x = 10 > factorial x 3628800
10. ೣࣻ۽ࠗఠ աৢ ࣻ ੓׮ > let factorial n = product [1..n] > let x = 10 > factorial x 3628800
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?
12. ч੄ ࢿ૕ > succ 1 2 > succ 2 3 > length ['a', 'b', 'c'] 3
13. ч੄ ࢿ૕ > succ ['a', 'b', 'c'] <interactive>: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']
14. ч੄ ࢿ૕ > length 1 <interactive>: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
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
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׮
17. factorial਷ ੿ࣻ݅ ߉ח׮ > factorial ['a', 'b', 'c'] <interactive>: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']
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
19. ੗ܐഋ ঌইࠁӝ (पઁח ੉ࠁ׮ ખ؊ ࠂ੟೤פ׮) > :t x x :: Integer > :t factorial factorial :: Integer -> Integer
20. ৈӝࢶ ׮ܖ૑ ঋח ׮਺ ઱ઁ • ؀ࣻ੸ ੗ܐഋ (algebraic data type) • Parametric polymorphism • ఋੑ௿ېझ (typeclass) • ⊥ (bottom) • ӝఋ ١١. ೞ૑݅ ށۄب ੌױ ೞझு ௏٬ द੘ оמ
21. ࠗप೧ࢲ દ࣠೤פ׮ bit.ly/haskell-kr-2015-04-04-type