Iterate abstract --Basic

不存在“无中生有”，物理学家寻找基本粒子，我们即是上帝，数学家用定义和公理确定这些“基本例子”。下面我来总结一下Haskell里面最Basic的基本粒子。

 

Bool

-- |The 'Bool' type is an enumeration.  It is defined with 'False'
-- first so that the corresponding 'Prelude.Enum' instance will give
-- 'Prelude.fromEnum' 'False' the value zero, and
-- 'Prelude.fromEnum' 'True' the value 1.
data  Bool  =  False | True  deriving (Eq, Ord)

        -- Read in GHC.Read, Show in GHC.Show

Ordering

-- | Represents an ordering relationship between two values: less
-- than, equal to, or greater than.  An 'Ordering' is returned by
-- 'compare'.
data Ordering = LT | EQ | GT deriving (Eq, Ord)

        -- Read in GHC.Read, Show in GHC.Show

 Char

{-| The character type 'Char' is an enumeration whose values represent
Unicode (or equivalently ISO\/IEC 10646) characters
(see <http://www.unicode.org/> for details).
This set extends the ISO 8859-1 (Latin-1) character set
(the first 256 charachers), which is itself an extension of the ASCII
character set (the first 128 characters).
A character literal in Haskell has type 'Char'.

To convert a 'Char' to or from the corresponding 'Int' value defined
by Unicode, use 'Prelude.toEnum' and 'Prelude.fromEnum' from the
'Prelude.Enum' class respectively (or equivalently 'ord' and 'chr').
-}
data Char = C# Char#


-- We don't use deriving for Eq and Ord, because for Ord the derived
-- instance defines only compare, which takes two primops.  Then
-- '>' uses compare, and therefore takes two primops instead of one.

 Int

data Int = I# Int#

-- ^A fixed-precision integer type with at least the range @[-2^29 .. 2^29-1]@.
-- The exact range for a given implementation can be determined by using
-- 'Prelude.minBound' and 'Prelude.maxBound' from the 'Prelude.Bounded' class.

 Integer

-- | Arbitrary-precision integers.
data Integer    


   = S# Int#
                            -- small integers
#ifndef ILX


   | J# Int# ByteArray#
                 -- large integers
#else


   | J# Void BigInteger
                 -- .NET big ints

foreign type dotnet "BigInteger" BigInteger

#endif

 Float

-- | Single-precision floating point numbers.
-- It is desirable that this type be at least equal in range and precision
-- to the IEEE single-precision type.
data Float      = F# Float#

 Double

-- | Double-precision floating point numbers.
-- It is desirable that this type be at least equal in range and precision
-- to the IEEE double-precision type.
data Double     = D# Double#

 Basic Monads(有些不合时宜，先放在这里）

IO Monad

{-|
A value of type @'IO' a@ is a computation which, when performed,
does some I\/O before returning a value of type @a@.  

There is really only one way to \"perform\" an I\/O action: bind it to
@Main.main@ in your program.  When your program is run, the I\/O will
be performed.  It isn't possible to perform I\/O from an arbitrary
function, unless that function is itself in the 'IO' monad and called
at some point, directly or indirectly, from @Main.main@.

'IO' is a monad, so 'IO' actions can be combined using either the do-notation
or the '>>' and '>>=' operations from the 'Monad' class.
-}
newtype IO a = IO (State# RealWorld -> (# State# RealWorld, a #))

 Maybe Monad

-- | The 'Maybe' type encapsulates an optional value.  A value of type
-- @'Maybe' a@ either contains a value of type @a@ (represented as @'Just' a@), 
-- or it is empty (represented as 'Nothing').  Using 'Maybe' is a good way to 
-- deal with errors or exceptional cases without resorting to drastic
-- measures such as 'error'.
--
-- The 'Maybe' type is also a monad.  It is a simple kind of error
-- monad, where all errors are represented by 'Nothing'.  A richer
-- error monad can be built using the 'Data.Either.Either' type.

data  Maybe a  =  Nothing | Just a


  deriving (Eq, Ord)

 Either Monad

{-|

The 'Either' type represents values with two possibilities: a value of
type @'Either' a b@ is either @'Left' a@ or @'Right' b@.

The 'Either' type is sometimes used to represent a value which is
either correct or an error; by convention, the 'Left' constructor is
used to hold an error value and the 'Right' constructor is used to
hold a correct value (mnemonic: \"right\" also means \"correct\").
-}
data  Either a b  =  Left a | Right b   deriving (Eq, Ord )