1.
10
ruicc.rail@gmail.com

2.
(Ruichi Kousuke)
@ruicc
http://d.hatena.ne.jp/ruicc

3.
Haskell

4.
10
!!

5.
Haskell Advent Calendar
Haskell Advent Calender
2
http://partake.in/events/eaea52c2-61ef-46d5-
a855-3a2dde459e3a

6.
Haskell Advent Calendar2011 2
ruicc.rail@gmail.com

7.
A Haskell
B
A
B
A ...

8.
(OO)
(OO) (Haskell)
(Haskell)
10

9.
(OO) (Haskell)
(OO) (Haskell)

10.
(OO)
= +

11.
(OO)
= +

12.
(OO) (Haskell)
(OO) (Haskell)
Haskell

13.
(Algebraic Data Type)
(Set)

14.
Tuple ( )

15.
or
Bool
True or False

16.
data
data IntOrSome a = MkInt Int
| MkA a

17.
data
data IntOrSome a = MkInt Int
| MkA a
(OO )

18.
data type
data IntOrSome a = MkInt Int
| MkA a
type IntOrStr = IntOrSome String

19.
( )
add :: Int -> Int -> Int
add a b = a + b

20.
(OO)
class IntAndStr {
private Int field1;
private String field2;
public IntAndStr (Int i, String s) {
field1 = i; field2 = s;
}
}
a = new IntAndStr(42, “aiueo”);

21.
Haskell
data IntAndStr = MkIS Int String
let a = MkIS 42 “aiueo”

22.
(OO)

23.
Haskell
data Bool = False | True
data Maybe a = Nothing | Just a
data Either a b = Left a | Right b

24.
(OO)

25.
Haskell
data List a = Nil | Cons a (List a)
data Tree a = Leaf a
| Node (Tree a) (Tree a)

26.
(OO) ..

27.
FAQ
Q: Haskell private
A1: Python dis
A2: Javascript ( )

28.
Haskell private( )
Haskell private
module

29.
Haskell private:
where
module

30.
OOP
(OO)

31.
:Haskell

32.
Y

33.
(OO)
= +

34.
( )
( )

35.
Haskell

36.
FAQ
C++ Python
Y
Y Haskell

37.
Haskell ( )
C++,Python
C++ :
Python : C3

38.
FAQ
Scala Trait
scalaz Trait
Haskell

39.
class
built-in Eq
class Eq a where
(==), (/=) :: a -> a -> Bool

40.
class
class Eq a where
(==), (/=) :: a -> a -> Bool

41.
class instance
class instance
Eq
class Eq a where
(==), (/=) :: a -> a -> Bool
MyType
instance Eq MyType where
x == y = ...
-- (==) :: MyType -> MyType -> Bool

42.
class
Eq
class (Eq a) => Ord a where
(<=) :: a -> a -> Bool Ord
...

43.
class
class (Eq a, Show a) => Num a where
(+) :: a -> a -> a
...
Show Eq
Num

44.
Read
Show
instance
Typeable
Bounded Ix
Enum Data
Ord Eq
instance
MyType

45.
deriving
data deriving
data MyType a b c = A a | B b | C c
deriving (Eq, Ord, Show, Read)
Read
Show
Ord Eq
MyType

46.
deriving FAQ
URL: http://www.haskell.org/ghc/docs/7.2.2/html/
users_guide/deriving.html

47.
Haskell
Haskell

48.
instance Eq (Maybe Int)
:: *
instance Monad Maybe
:: * -> *

49.
Monad, Functor, Applicative