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1 Haskell

2 2

3 1988 B4 Sun

4 Unix Magazine Unix Magazine UNIX RFC FYI (For Your Information) 4

5 IP PEM (Privacy Enhanced Mail) WIDE Project mh-e PEM 5

6 6

7 Unix Magazine PGP PGP 1 7

8 Mew (MIME) Mew Emacs Emacs XEmacs 8

9 Emacs Mew off Mew Emacs read-passwd gnu.org 9

10 IIJ KAME IIJ 10

11 KAME KAME WIDE BSD IPv6 IPsec Mobile IPv6 IIJ NEC BSD IPv6 IPsec Mobile IPv6 Mac IPv6 KAME 11

12 IETF Internet Engineering Task Force RFC (Request For Comments) RFC (ISO) ISO OSI(Open Systems Interconnection) We reject: kings, presidents and voting. We believe in: rough consensus and running code. IPv6 IETF 12

14 JavaScript JavaScript Firemacs Douglas Crockford JavaScript: for JavaScript C JavaScript: The Good Parts JSLint switch Crockford JSLint Crockford for 14

15 Emacs Lisp Haskell 15

16 Haskell Q1) Haskell A) A) Q2) Haskell Web Marlow Developing a high-performance web server in Concurrent Haskell A) IO A) Haskell (c) Simon Peyton Jones 16

17 17

18 18

19 { 10, 20, 30, 40, 50 } 0 n n 10 * * * * *4 =

20 10 * * * * *4 = 400 for 20

21 for Douglas Crockford JavaScript: for JavaScript C JavaScript C Java Lisp Scheme 21

22 22

23 for for for for for ) for two days for (i = 0; i < N; i++) { } 0 N = (N - 1) = N 1/3 + 1/3 + 1/3 1 23

24 Java for public static int func(int[] ar) { int ret = 0; for (int i = 0; i < ar.length; i++) { ret = ret + ar[i] * i; } return ret; } int[] inp = {10,20,30,40,50}; func(inp);

25 Haskell MapReduce zip [0..] [10,20,30,40,50] [(0,10),(1,20),(2,30),(3,40),(4,50)] map (\(i,x) -> x*i) [0,20,60,120,200] foldl (+) 0 ((((0 + 0) + 20) + 60) + 120) func = foldl (+) 0. map (\(i,x) -> x*i). zip [0..] func [10,20,30,40,50]

26 26

27 27

28 Haskell -- IORef OCaml -- ref 28

29 29

30 30

31 Haskell (+) :: Num a => a -> a -> a sort :: Ord a => [a] -> [a] filter :: (a -> Bool) -> [a] -> [a] hgetline :: Handle -> IO String writefile :: FilePath -> String -> IO () writeioref :: IORef a -> a -> IO () IO IO 31

32 OCaml (+) : int -> int -> int sort : ( a -> a -> int) -> a list -> a list filter : ( a -> bool) -> a list -> a list input_line : in_channel -> string write : file_descr -> string -> int -> int -> int (:=) : a ref -> a -> unit 32

33 33

34 34

35 FFI(Foreign Function Interface) Haskell C C Haskell C safe unsafe Haskell GC Ptr a ForeignPtr a 35

36 FFI foreign {-# LANGUAGE ForeignFunctionInterface #-} import Foreign.C.Types foreign import ccall unsafe "sin" c_sin :: CDouble -> CDouble -- realtofranc Double CDouble mysin :: Double -> Double mysin x = realtofrac (c_sin (realtofrac x)) 36

37 FFI IO {-# LANGUAGE ForeignFunctionInterface #-} import Foreign import Foreign.C.String import Foreign.C.Types -- time foreign import ccall unsafe "time" c_time :: Ptr CTime -> IO CTime -- foreign import ccall unsafe "ctime" c_ctime :: Ptr CTime -> IO CString timestring :: IO String timestring = alloca $ \ctime_ptr -> do -- _ <- c_time ctime_ptr str <- c_ctime ctime_ptr -- str peekcastring str -- CString String 37

38 .hsc {-# LANGUAGE ForeignFunctionInterface #-} import Data.UnixTime.Types import Foreign.C.Error import Foreign.C.Types import Foreign.Marshal.Alloc import Foreign.Ptr import Foreign.Storable #include <time.h> #include <sys/time.h> type CTimeVal = () type CTimeZone = () foreign import ccall unsafe "gettimeofday" gettimeofday :: Ptr CTimeVal -> Ptr CTimeZone -> IO CInt getunixtime :: IO UnixTime getunixtime = allocabytes (#const sizeof(struct timeval)) $ \ p_timeval -> do gettimeofday p_timeval nullptr sec <- (#peek struct timeval,tv_sec) p_timeval usec <- (#peek struct timeval,tv_usec) p_timeval return $ UnixTime sec usec 38

39 hsc2hs.hs {-# LANGUAGE ForeignFunctionInterface #-} import Data.UnixTime.Types import Foreign.C.Error import Foreign.C.Types import Foreign.Marshal.Alloc import Foreign.Ptr import Foreign.Storable type CTimeVal = () type CTimeZone = () foreign import ccall unsafe "gettimeofday" c_gettimeofday :: Ptr CTimeVal -> Ptr CTimeZone -> IO CInt getunixtime :: IO UnixTime getunixtime = allocabytes (8) $ \ p_timeval -> do c_gettimeofday p_timeval nullptr sec <- ((\hsc_ptr -> peekbyteoff hsc_ptr 0)) p_timeval usec <- ((\hsc_ptr -> peekbyteoff hsc_ptr 4)) p_timeval return $ UnixTime sec usec 39

40 40

41 41

42 public class Person { String name; int age; } Java DB HashMap<String,Person> db = new HashMap<String,Person>(); Person sazae = new Person(" ", 24); Person fune = new Person(" ", 52); map.put(" ",sazae); map.put(" ",fune); // " " 42

43 String me = " "; Person mother = db.get(me); // " " Person gramma = db.get(mother.name); // " " String me = " "; Person mother = db.get(me); // " " Person gramma = db.get(mother.name); // null String me = " "; Person mother = db.get(me); // null Person gramma = db.get(mother.name); // 43

44 String me = " "; Person mother = db.get(me); Person gramma = null; if (mother!= null) { gramma = db.get(mother.name); } 44

45 <Person> get(<string>) null null null Java null null 45

46 46

47 Haskell DB data Person = Person String Int name :: Person -> String name (Person n _) = n age :: Person -> Int age (Person _ a) = a db :: [(String, Person)] db = [(" ", Person " " 24),(" ", Person " " 52)] 47

48 lookup Maybe DB lookup :: String -> [(String, Person)] -> Maybe Person Person Maybe Person : Nothing : Just (Person " " 24) 48

49 Maybe Person case... of findgramma :: String -> Maybe Person findgramma me = case lookup me db of Nothing -> Nothing Just mother -> lookup (name mother) db 49

50 50

51 (Java ) String me = " "; Person mother = db.get(me); Person gramma = null; if (mother!= null) { gramma = db.get(mother.name); } String me = " "; Person mother = db.get(me); Person gramma = null; Person ggramma = null; if (mother!= null) { gramma = db.get(mother.name); if (gramma!= null) { ggramma = db.get(gramma.name); } } 51

52 (Haskell ) findgramma :: String -> Maybe Person findgramma me = case lookup me db of Nothing -> Nothing Just mother -> lookup (name mother) db findggramma :: String -> Maybe Person findggramma me = case lookup me db of Nothing -> Nothing Just mother -> case lookup (name mother) db of Nothing -> Nothing Just gramma -> lookup (name gramma) db 52

53 53

54 Maybe Maybe Java data Bool = False True data Maybe a = Nothing Just a data Either l r = Left l Right r 54

55 isalive me && isalive mother Maybe a findmother me &&> findmother mother 55

56 &&> mx &&> f = case mx of Nothing -> Nothing Just x -> f x findggramma :: String -> Maybe Person findggramma me = lookup me db &&> \mother -> lookup (name mother) db &&> \gramma -> lookup (name gramma) db ( ) findggramma :: String -> Maybe Person findggramma me = case lookup me db of Nothing -> Nothing Just mother -> case lookup (name mother) db of Nothing -> Nothing Just gramma -> lookup (name gramma) db 56

57 57

58 58

59 Web "/" " /index.html.ja", " /index.html.en", " /index.html" (200 OK) (200 OK) "/" " /index.html.ja", " /index.html.en", " /index.html" " /" (MovedPermanently 301) NotFound (404) 59

60 IO ios :: [IO ()] ios = [ putstrln "Hello!", putstrln "Hi!" ] main :: IO () main = do ios!! 1 ios!! 0 Hi! Hello! Hi! 60

61 IO or Haskell IO getchar :: IO Char IO getchar :: IO Char main IO 61

62 OCaml Haskell IO io unit a io type world = unit type a io = world -> a (* write : string -> unit io *) let write str = fun () -> print_string str (* read : string io *) let read = read_line (* run : a io -> a *) let run prog = prog () (* (>>=) : a io -> ( a -> b io) -> b io *) let (>>=) io f = fun () -> let res = run io in run (f res);; run (read >>= write);; 62

63 files :: [FilePath] [ " /index.html.ja", " /index.html.en", " /index.html"] HTTP HTTP sendfile :: FilePath -> IO () ios :: [IO ()] ios = map sendfile files 63

64 64

65 Java try catch try { 1; } catch (...) { try { 2; } catch (...) { 3; } } 65

66 Haskell Haskell catch catch :: IO a -> (IOError -> IO a) -> IO a Java catch ( 1 ) (\_ -> catch ( 2 ) (\_ -> 3 ) ) ) catch 66

67 > IO ( >) :: IO a -> IO a -> IO a x > y = catch x (\_ -> y) 1 > 2 > 3 Java ( ) catch ( 1 ) (\_ -> catch ( 2 ) (\_ -> 3 ) ) ) 67

68 ios :: [IO ()] ios = map sendfile files > foldr1 ( >) ios 68

69 69

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71 71

72 / / Haskell / 72

73 73

74 74

75 ( ) / 75

76 = 10 76

77 epoll/kqueue ( ) 77

78 I/O I/O 78

79 ( ) ( ) 79

80 ( ) var x = f(); var y = g(x); var z = h(y); ( ) f(function(x) { g(x,function(y) { h(y,function(z) {... }); }); }); 80

81 1 1 81

82 1 1 82

83 83

84 Ruby Ruby Ruby

85 Haskell OK 85

86 ( ) 86

87 + / (thundering herd) Blocking accept() Non-blocking accept() 87

88 88

89 libevent libev libuv select() Oneshot OS 89

90 nginx 90

91 91

presen.gby

presen.gby kazu@iij.ad.jp 1 2 Paul Graham 3 Andrew Hunt and David Thomas 4 5 Java 6 Java Java Java 3 7 Haskell Scala Scala 8 9 Java Java Dean Wampler AWT ActionListener public interface ActionListener extends EventListener