Programming haskell chapter10

(Ruichi Kousuke)

@ruicc

http://d.hatena.ne.jp/ruicc

Haskell Advent Calendar

Haskell Advent Calender
2

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a855-3a2dde459e3a

Haskell Advent Calendar2011 2

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(OO)

(OO) (Haskell)

(Haskell)

10

(OO) (Haskell)

(OO) (Haskell)

(OO) (Haskell)

(OO) (Haskell)

Haskell

data

data IntOrSome a = MkInt Int

| MkA a

data


| MkA a

(OO )

data type


| MkA a

type IntOrStr = IntOrSome String

( )

add :: Int -> Int -> Int

add a b = a + b

(OO)

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

Haskell

data IntAndStr = MkIS Int String

let a = MkIS 42 “aiueo”

Haskell

data Bool = False | True

data Maybe a = Nothing | Just a

data Either a b = Left a | Right b

Haskell

data List a = Nil | Cons a (List a)

data Tree a = Leaf a
| Node (Tree a) (Tree a)

FAQ

Q: Haskell private

A1: Python dis

A2: Javascript ( )

Haskell private( )

Haskell private

module

Haskell private:

where

module

FAQ

C++ Python

Y

Y Haskell

Haskell ( )

C++,Python

C++ :

Python : C3

FAQ

Scala Trait

scalaz Trait
Haskell

class

built-in Eq

class Eq a where

(==), (/=) :: a -> a -> Bool

class

class Eq a where

(==), (/=) :: a -> a -> Bool

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

MyType
instance Eq MyType where
x == y = ...
-- (==) :: MyType -> MyType -> Bool

class

Eq

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

class

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

Num

Read
Show
instance
Typeable
Bounded Ix
Enum Data

Ord Eq
instance

MyType

deriving

data deriving

data MyType a b c = A a | B b | C c

deriving (Eq, Ord, Show, Read)
Read
Show
Ord Eq

MyType

deriving FAQ

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

instance Eq (Maybe Int)

:: *
instance Monad Maybe
:: * -> *

Programming haskell chapter10

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