Chapter 23

module Data.Word (  
    Word,  Word8,  Word16,  Word32,  Word64  
  ) where

23.1 Unsigned integral types

This module provides unsigned integer types of unspecified width (Word) and fixed widths (Word8, Word16, Word32 and Word64). All arithmetic is performed modulo 2^n, where n is the number of bits in the type.

For coercing between any two integer types, use fromIntegral. Coercing word types to and from integer types preserves representation, not sign.

The rules that hold for Enum instances over a bounded type such as Int (see the section of the Haskell language report dealing with arithmetic sequences) also hold for the Enum instances over the various Word types defined here.

Right and left shifts by amounts greater than or equal to the width of the type result in a zero result. This is contrary to the behaviour in C, which is undefined; a common interpretation is to truncate the shift count to the width of the type, for example 1 << 32 == 1 in some C implementations.

data Word
A Word is an unsigned integral type, with the same size as Int.

instance Bounded Word
instance Enum Word
instance Eq Word
instance Integral Word
instance Num Word
instance Ord Word
instance Read Word
instance Real Word
instance Show Word
instance Ix Word
instance Storable Word
instance Bits Word

data Word8
8-bit unsigned integer type

instance Bounded Word8
instance Enum Word8
instance Eq Word8
instance Integral Word8
instance Num Word8
instance Ord Word8
instance Read Word8
instance Real Word8
instance Show Word8
instance Ix Word8
instance Storable Word8
instance Bits Word8

data Word16
16-bit unsigned integer type

instance Bounded Word16
instance Enum Word16
instance Eq Word16
instance Integral Word16
instance Num Word16
instance Ord Word16
instance Read Word16
instance Real Word16
instance Show Word16
instance Ix Word16
instance Storable Word16
instance Bits Word16

data Word32
32-bit unsigned integer type

instance Bounded Word32
instance Enum Word32
instance Eq Word32
instance Integral Word32
instance Num Word32
instance Ord Word32
instance Read Word32
instance Real Word32
instance Show Word32
instance Ix Word32
instance Storable Word32
instance Bits Word32

data Word64
64-bit unsigned integer type

instance Bounded Word64
instance Enum Word64
instance Eq Word64
instance Integral Word64
instance Num Word64
instance Ord Word64
instance Read Word64
instance Real Word64
instance Show Word64
instance Ix Word64
instance Storable Word64
instance Bits Word64