Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Speaker Deck
PRO
Sign in
Sign up
for free
初めての関数型プログラミング
petitviolet
September 19, 2015
Programming
1
1.3k
初めての関数型プログラミング
Haskellで始める関数型プログラミング
ざっくりとした紹介とモナド
https://ngineerxiv.doorkeeper.jp/events/29760
petitviolet
September 19, 2015
Tweet
Share
More Decks by petitviolet
See All by petitviolet
petitviolet
14
7.4k
petitviolet
0
1k
petitviolet
1
760
petitviolet
8
2.1k
petitviolet
1
410
petitviolet
3
1.8k
petitviolet
0
1.4k
petitviolet
17
4.3k
petitviolet
1
56
Other Decks in Programming
See All in Programming
dora1998
0
180
doyaaaaaken
1
330
imk2o
0
210
samjulien
0
420
chatii
2
290
minodriven
37
29k
dqneo
0
150
mathetake
7
2.2k
yusuke57
0
120
tmyk110
1
170
borkdude
1
180
chimerast
0
350
Featured
See All Featured
mongodb
23
3.9k
rocio
155
11k
lauravandoore
440
28k
bryan
100
11k
colly
188
14k
nonsquared
81
3.4k
myddelton
109
11k
tmm1
61
9.9k
zakiwarfel
88
3.4k
roundedbygravity
242
21k
chriscoyier
779
240k
3n
163
22k
Transcript
ॳΊͯͷ ؔܕϓϩάϥϛϯά @petitviolet Fringe81 Co., Ltd.
About Me • খࢵ ߂و(Hiroki Komurasaki) • @petitviolet • ৽ଔ1(15ଔ)
• Fringe81͍ͬͯ͏ΞυςΫͷձࣾ • Android/iOSͷࠂSDK։ൃ
ॳΊͯͷ ؔܕϓϩάϥϛϯά
ॳΊͯͷ ؔܕϓϩάϥϛϯά
ॳΊͯͷ Haskell
What is Haskell • ७ਮؔܕϓϩάϥϛϯάݴޠ • ԆධՁ • ੩తܕ͚/ܕਪ •
ͳͲ
७ਮؔܕʁ • ෭࡞༻͕ແ͍ • ࢀরಁաੑ • ಉ͡ೖྗʹରͯ͠ৗʹಉ͡ग़ྗ • ؔୈҰڃ •
jsͷΑ͏ʹؔΛΦϒδΣΫτͱͯ͠ѻ͑Δ
෭࡞༻͕ͳ͍ • ༩͑ΒΕͨҾͷΈΛͬͯ݁ՌΛฦ͢ • ΦϒδΣΫτͷঢ়ଶͱ͔جຊతʹແ͍
ؔʹ͍ͭͯ
໋ྩܗݴޠͷؔ ίϯϐϡʔλʹରͯ͠ ԿΛ͢Δͷ͔Λ͑Δ
ؔܕϓϩάϥϛϯάݴޠͰ ίϯϐϡʔλʹରͯ͠ ԿͰ͋Δͷ͔Λ͑Δ
?
ؔԿͰ͋Δ͔Λ͑Δ • ϑΟϘφονྻ // Python def fib(n): if n <
2: return n return fib(n - 1) + fib(n - 2) [fib(i) for i in range(1, 11)]
ؔԿͰ͋Δ͔Λ͑Δ • ϑΟϘφονྻ // Haskell fib :: [Int] fib =
1 : 1 : zipWith (+) fib (tail fib) take 10 fib 1, 1, 2, 3, 5, 8, 13, … 1, 1, 2, 3, 5, 8, 13, … 1, 1, 2, 3, 5, 8, 13,21…
ԆධՁ • ඞཁͳ͚ͩΛධՁ͢Δͷ͕ԆධՁ • ྻࣗମΛఆٛग़དྷΔ • fibؔແݶͷϑΟϘφονྻΛฦ͢ // Haskell fib
:: [Int] fib = 1 : 1 : zipWith (+) fib (tail fib) fib # ࢮ take 10 fib
ؔ߹ • Unixత • খ͞ͳؔΛΈ߹Θͤͯେ͖ͳͷΛ࡞Δ Prelude> length "hello" 5 Prelude>
show 100 "100" Prelude> (length . show) 100 3
ϥϜμࣜ Prelude> let add = \x y -> x +
y Prelude> foldr add 0 [1..10] 55
\ࢥ͍͖ͬΓΛࡉΊΔͱ ΪϦγϟจࣈͷϥϜμλʹ ݟ͑·͢ΑͶɻ ͍͢͝Haskellֶָ͘͠΅͏ʂ p73
ͳΔ΄Ͳ
ܕʹ͍ͭͯ
੩తܕ͚ && ܕਪ Prelude> let a = 5 + 4
Prelude> :t a a :: Num a => a Prelude> let b :: Num a => a; b = (5 :: Num a => a) + (4 :: Num a => a) Prelude> :t b b :: Num a => a
• ܕͷ࣋ͭੑ࣭Λද͢ΠϯλʔϑΣʔεͬΆ͍ • Numʹଐ͢ܕ””ͱͯ͠ͷੑ࣭Λ࣋ͭ ܕΫϥε Prelude> :t 10 10 ::
Num a => a Prelude> :t 10 :: Int 10 :: Int :: Int Prelude> :t 10 :: Double 10 :: Double :: Double
Ϟφυ
Ϟφυͷલʹཧղ͍ͨͭ͠ • ϑΝϯΫλʔ • ΞϓϦΧςΟϒϑΝϯΫλʔ class Functor f where fmap
:: (a -> b) -> f a -> f b class (Functor f) => Applicative f where pure :: a -> f a (<*>) :: f (a -> b) -> f a -> f b
• จ຺Λ࣋ͭܭࢉΛ࣮ݱ͢ΔΈ • Maybe͋Δ͔͠Εͳ͍͠ɺͳ͍͔ • Listෳͷ͕͋Δ͔͠Εͳ͍ Ϟφυ Prelude> Just 10
>>= (\x -> Just(x + 4)) Just 14 Prelude> Nothing >>= (\x -> Just(x + 4)) Nothing
• จ຺Λ࣋ͭܭࢉΛ࣮ݱ͢ΔΈ • Maybe͋Δ͔͠Εͳ͍͠ɺͳ͍͔ • Listෳͷ͕͋Δ͔͠Εͳ͍ Ϟφυ Prelude> [1, 2]
>>= (\x -> [10, 20] >>= (\y -> [x, y])) [1,10,1,20,2,10,2,20] Prelude> [1, 2] >>= (\x -> [] >>= (\y -> [x, y])) []
class Monad m where return :: Monad m => a
-> m a (>>=) :: Monad m => m a -> (a -> m b) -> m b … B monad C monad Just 10 >>= (\x -> Just(show x)) = Just “10” B monad SFUVSOB return 10 :: Maybe Int = Just 10 C monad B
• จ຺Λ࣋ͭಉ࢜ͷܭࢉΛ៉ྷʹΔͨΊͷΈ • ϞφυͱɺϞφυΛฦΓͱ͢ΔؔΛ ͍͍ײ͡ʹΈ߹ΘͤͯϞφυΛಘΔ • ܭࢉ݁ՌΛϞφυʹ͢Δ • Just 10
ͱ show ΛͬͯJust “10” • ࣦഊͯͨ͠ΒશମΛࣦഊͤ͞Δ • Nothing Λ show ͠Α͏ͱ͢Δͱ Nothing Ϟφυ
We are hiring! fringe81.com/recruit