Fun of Types

Transcript

1. ͨͷ͍͠ܕ ج൫(ɹߴౡ
   ྄༞

2. ࣗݾ঺հ w ߴౡ
   ྄༞ʢ!STUʣ
   w ޷͖ͳ΋ͷɿখઆɺϚϯΨɺΞχϝʢ4'த৺ʣ
 ΧϥΦέɺຑ੃ɺόεέ
   w

3. ຋༁ w ʰϫϯεɾΞϙϯɾΞϯɾΞϧΰ ϦζϜʱͱ͍͏ຊΛ༁͠·ͨ͠ ʢʣ
 IUUQTXXXBNB[PODPKQEQ 
   w l*NQSBDUJDBM
   1ZUIPO
   1SPKFDUT
   1MBZGVM
   1SPHSBNNJOH
   "DUJWJUJFT
   

   UP
   .BLF
   :PV
   4NBSUFSz
 ͱ͍͏ຊΛ຋༁༧ఆ
 ϨϏϡΞืूதͰ͢ʂ

4. ܕ w ࠷ۙ͸੩తܕ෇͚͕ਓؾʁʢ5ZQF4DSJQUɺ(Pʣ
   w ܕͷ͋Δݴޠɾܕͷແ͍ݴޠ
   w ܕ͸ͨͷ͍͠ʂʂʂ

5. ܕͷ֊૚ʢ+BWBʣ Collection List Set ArrayList LinkedList HashSet TreeSet add(E e)

   get(int index)

6. ܕͷ֊૚ʢ)BTLFMMʣ Functor Applicative
 Functor Monad [] Maybe IO r ->

   fmap (<$>) (>>=) Ϧετ ೖग़ྗ ؔ਺ ͍ΘΏΔ0QUJPOBM

7. 'VODUPS GNBQ ͷྫ fmap (show . (* 3)) [1..4] --

   3ഒͯ͠จࣈྻʹม׵
 => ["3", "6", "9", "12"] fmap fromEnum (Just 'F') -- ίʔυϙΠϯτΛऔಘ
 => Just 70 fmap fromEnum Nothing -- த਎͕ͳ͚Ε͹Կ΋͠ͳ͍
 => Nothing

8. 'VODUPS GNBQ ͷղऍ w 'VODUPSΛശͱଊ͑Δͱɺ
 GNBQ͸ശͷܗΛม͑ͣʹத਎Λม͑Δૢ࡞ fmap :: Functor f

   => (a -> b) -> f a -> f b
 fmap :: (a -> b) -> [a] -> [b]
 fmap :: (a -> b) -> Maybe a -> Maybe b

9. 'VODUPSͱͯ͠ͷؔ਺ w ؔ਺
   S
   
   B
   ΋'VODUPSʢSΛ౉͢ͱBΛฦͯ͘͠ΕΔശʁʣ
 Ͱ͸GNBQ͸Կʁ fmap :: Functor f => (a

   -> b) -> f a -> f b
 fmap :: (a -> b) -> (r -> a) -> (r -> b) fmap = (.) fmap (fmap show (* 3)) [1..4] w S
   
   B
   ͱ
   B
   
   C
   Λͭͳ͛Δ
   
   ؔ਺߹੒ʂ
   w ͔ͩΒ͜͏΋ॻ͚Δ

10. .POBEͱ  w ҎԼͷͭͷίʔυ͸౳Ձ
    w Ұͭ໨ͷ݁Ռ͸ແࢹͯ͠ɺೋͭ໨Λऔಘ
    print [1..4] >> print

    "hoge" do
 print [1..4]
 print "hoge" (>>) :: Monad m => m a -> m b -> m b
 (>>) :: IO a -> IO b -> IO b

11. .POBEͱͯ͠ͷϦετ w ҎԼ͸Ͳ͏ͳΔʁ
    w 
    ͸
    
    ͭ·Γ
    qBU.BQ
    ͷಛघܗͳͷͰʜ
 ͪͳΈʹҎԼͷΑ͏ʹ΋ॻ͚Δ
    (>>)

    :: Monad m => m a -> m b -> m b
 (>>) :: [a] -> [b] -> [b] [1..4] >> "hoge" do
 [1..4]
 "hoge"

12. ·ͱΊ w Ϧετ΋ೖग़ྗ΋ؔ਺΋ಉ͡΋ͷ
    w ܕ͸ͨͷ͍͠ʂʂ)BTLFMM΋ͨͷ͍͠ʂʂ
    w ܕ͕ແ͍ੈքͷ࿩͸ผͷػձʹ