コードで遊ぼう Haskell #2.1

Sample Codes

https://bitbucket.org/BP-YooWaan/enjoycode/src/

Transcript

1. HASKELL ίʔυͰ͋ͦ΅͏ #2.1
2. ϫλγ ABOUT ME ϑΨϑΨϑΨϑΨϑΨϑΨϑΨϑΨ ϑΨϑΨϑΨϑΨϑΨϑΨϑΨϑΨ ϑΨϑΨϑΨϑΨϑΨϑΨϑΨϑΨ
3. ໨࣍ ❖ എܠ ❖ ηοτΞοϓ ❖ Ϗϧυ ❖ ςετ ❖ cabal
4. #2 ͔Βͷଓ͖
5. ཱͪ͸͔ͩΔ น
6. น
7. น น
8. น น น น
10. ؔ਺ϓϩάϥϚʔ นΛ৐Γӽ͑ͨ݁Ռ
11. എܠ ؔ਺ܕϓϩάϥϛϯά Ҏ֎ϓϩάϥϚͰͳ͍෩ை ɾɾɾɾɾɾ https://gist.github.com/Gab-km/2419511
12. എܠ OOP΁ͷ࠘Έઅɾɾɾ http://qiita.com/lambda-knight/items/fb7530232912dc4176c4
13. ࢀߟ·ͰʹɿOOP͸ѱͰ͸ͳ͍Α http://itpro.nikkeibp.co.jp/article/Watcher/20061129/255258/?rt=nocnt
14. ͱ͍͏ͷΛड͚ͯ ࣮ࡍʹॻ͍ͯΈ·ͨ͠ ྑ͍ѱ͍͕఻Θͳ͍࣌͸͢Έ·ͤΜ
15. ͸͡Ί͍͖ͯ·͢
16. ؀ڥ ❖ ݴޠ ❖ Haskell
 The Glorious Glasgow Haskell Compilation System, version 7.10.2 ❖ Package؅ཧ ❖ cabal
 cabal-install version 1.22.6.0
 using version 1.22.4.0 of the Cabal library
17. ❖ Package؅ཧ ❖ stack version 0.1.6.0 ❖ cabal hell ճආ ❖ ෳ਺όʔδϣϯghcڞଘ ❖ ෳ਺cabalύοέʔδ
 ͷϓϩδΣΫτϏϧυՄೳ
18. ։ൃ؀ڥ ❖ ։ൃσΟϨΫτϦ ɹHaskell Πϯετʔϧ $ brew install ghc
 $ yum install haskell
 $ apt-get install haskell-platform 
 ɹύοέʔδ؅ཧπʔϧΠϯετʔϧ $ brew intall cabal $ brew install haskell-stack (লུ)
19. ։ൃ؀ڥ ❖ cabal $ cabal init $ cabal configure $ cabal build $ cabal run $ cabal test $ cabal install $ stack new <project name> $ cd <project name> $ stack build $ stack exec <app name> $ stack test $ stack install ❖ stack
20. ४උ͕Ͱ͖·ͨ͠ ؆୯ͳྫͷίʔυΛॻ͍ͯΈ·͠ΐ͏
21. ͳΜ͔ྑ͛͞Λମݧʂʁ ੔਺ͷϦετ or ഑ྻΛೖྗͯ͠ɺ͔̌Β਺্͑͛ͯ n൪໨ͷཁૉʹ͸ n Λֻ͚ɺ͢΂ͯΛ଍͠߹ΘͤΔॲཧΛॻ͍ͯΈΑ͏ ͭ·Γ ೖྗ [ 10, 20, 30, 40 , 50 ] ͷ͜ΕΛ ͜͏͍͏෩ʹܭࢉ (10 × 0) + (20 × 1) + (30 × 2) + (40 × 3) + (50 × 4) = ?
22. ͳΜ͔ྑ͛͞::໋ྩΛॻ͍ͯ͘৔߹ def func(ary) sum = 0 i = 0 ary.each{|x| sum += x * i i += 1 } return sum end puts func([ 10,20,30,40,50 ]) ❖ ruby def func(ary): sum = 0 for i, v in enumerate(ary): sum += i * v return sum print func([10,20,30,40,50]) ❖ python ഁյత୅ೖͷੈք
23. ͳΜ͔ྑ͛͞::Haskell ❖ Haskell func :: [Int] -> Int func list = foldl (+) 0 -- ৞ΈࠐΈؔ਺ $ map( \(i,x) -> x*i ) -- Ϛοϓؔ਺ $ zip [0..] list -- ೋͭͷϦετΛϖΞʹ main = print (func([10,20,30,40,50])) map , reduce ؔ਺߹੒
24. ͳΜ͔ྑ͛͞::pythonͰॻ͘ͱ ❖ python # -*- coding: utf-8 -*- # def func(ary): return reduce( lambda a,b : a+b , map( lambda (i,x) : i*x , zip( range(0,len(ary), 1), ary) )) print func([ 10, 20, 30, 40, 50 ])
25. ͜͜·ͰͰ ❖ ഁյత୅ೖ͕ͳ͍ ❖ ७ਮ ❖ λΠϓྔ΋গͳ͍ ❖ h( g( f() ) ) ΑΓ h ◦ g ◦ f ͳײ͕͍͍͡ΑͶ ͍͍͡ΌΜʂʂ
26. –ʹ͜ʹ͜΀Μ “͋ΒΒ͓΍͓΍ ͦΕ͔Βυϯυίγϣ͒͒” จ๏ͱ͔͸লུ͠·͢ ؔ਺Ͱ७ਮʹͰ͖Δ͜ͱ ͝঺հ͠·͢ ࣍͸
27. ԣͷຊͷҰ෦Λ ঺հ͠·͢
28. ྫʣࣗ༝࠷খ਺ɿ໰୊ ༩͑ΒΕͨࣗવ਺ͷ༗ݶू߹ X ʹؚ·Εͳ͍࠷খͷࣗવ਺Λ໭Δ໰୊ ྫɿ [ 08, 23, 09, 00, 12, 11, 01, 10, 13, 07, 41, 04, 14, 21, 05, 17, 03, 19, 02, 06 ] ʹؚ·Εͳ͍࠷খͷࣗવ਺ΛͲ͏΍ͬͯ୳͔͢ʁ ಄͍͍෩ຯ: ೚ҙͷϦετͷ੔ྻ͸ઢܗ࣌ؒͰ͸Ͱ͖ͳ͍ɻʹ΋͔͔ΘΒͣ͜ͷ໰୊͸ઢܗ࣌ؒͰͷղ๏͕͍ͭ͘΋ଘࡏ͠·͢
29. ྫʣࣗ༝࠷খ਺ɿղ๏ [1] ୯७ʹର৅ͷ഑ྻͷ਺ࣈΛऔΓআ ͍ͯɺઌ಄ͷ਺ࣈΛฦ͢ [2] 0͔Βn·Ͱͷ n+1ݸͷεϩοτΛ ࣋ͭ࿦ཧ஋ͷ഑ྻΛ࡞੒ͯ͠ɺ͜ͷ ഑ྻΛԼ͔Βݟͯ࠷ॳʹFalseʹͳΔ
 [1] min1st :: [Int] -> Int min1st xs = head ( [0 ..] \\ xs ) [2] min2nd :: [Int] -> Int min2nd = search . checklist search :: Array Int Bool -> Int search = length . takeWhile id . elems checklist :: [Int] -> Array Int Bool checklist xs = accumArray (||) False (0,n) (zip (filter (<= n) xs) (repeat True)) where n = length xs
30. ྫʣࣗ༝࠷খ਺ɿղ๏ [3] ෼ׂ౷࣏๏ [3] minfree :: [Int] -> Int minfree xs = minform 0 (length xs, xs) minform :: Int -> (Int, [Int]) -> Int minform a (n,xs) | n == 0 = a | m == b - a = minform b (n-m, vs) | otherwise = minform a (m, us) where (us,vs) = partition (< b) xs b = a + 1 + n `div` 2 m = length us
31. ྫʣࣗ༝࠷খ਺ɿ݁Ռ [1] min1st O(n^2)ͷεςοϓͷख͕ؒඞཁ [2] min2nd ஝ੵؔ਺(accumArray)͕ఆ਺࣌ؒͰ͋Ε͹ɺ࿈૝഑ྻͷ௕͞ʹ ରͯ͠ઢܗ࣌ؒ [3] minfree खؒ T(n) = T( n div 2) + O(n) = O(n)
 
 3͸2ΑΓૣ͘1ΑΓ̎ഒ*଎͍ *؀ڥґଘ
32. ఻ΘΓ͖Βͳ͍ͱࢥ͍·͕͢ ❖ ϓϩάϥϛϯάӡࢉΛߦ͏৔߹ɺ؆୯ͳؔ਺ʹ෼ղͰ͖Δؔ਺ ελΠϧͷํ͕ɺखଓ͖ελΠϧΑΓ༏͍͠ ❖ ΫϥεɾจষΑΓɺؔ਺ͷํ͕؆ܿͰΞϧΰϦζϜͷઆ໌͠΍ ͍͢
33. ऴɹΘɹΓɹʹ
34. ߟ࡯ ❖ pros ❖ ίʔυ͕୹͍ ❖ ΞϧΰϦζϜ࣮૷͕༰қ
 (࿦ূ͠΍͍͢) ❖ ෳࡶͳࣄ͕؆୯ʹͰ͖Δ ❖ ੜ࢈ੑ޲্ ❖ όάͷࠞೖ͕গͳ͍ ❖ cons ❖ ෑډ͕Ϋιߴ͍ ❖ ։ൃ/อकऀ গͳ͍ ❖ νʔϜߏங͕ࠔ೉ ❖ LL ͱ͔ͳΜ͔΋͏໋ྩܕͰ͍͍ ΑͶʁ
35. ࢲͳΓͷ݁࿦ ❖ ศར͚ͩͲ ❖ ֶशίετ͕ߴ͍ ❖ ࢖͏ͷ͕೉͍͠
 ɹ㱺 ྲྀߦΓ͖Βͳ͍ͱࢥͬͯ͠·͏ ❖ Լهͷ΋ͷ͕χϡΞϯε͕ࣅ͍ͯΔͱࢥ͏ ❖ SOAP ❖ xhtml ศར ΤϯδχΞ ؔ਺ϓϩάϥϛϯά Τοηϯε ݍ࿦ น
36. ʹ͜ʹ͜ ʹ͜ʹ͜ ʹͬ͜Γ ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ ࣍͸͋Δͷ͔ʁ ࣍͸΋ͬͱߟ͑ͳ͍͍ͯ͘Ϡπʹ͠Α͏