This library provides unsigned integers of various sizes. The types supported are as follows:
|type||number of bits|
For each type W above, we provide the following functions and instances. The type I refers to the signed integer type of the same size.
data W -- Unsigned Ints instance Eq W instance Ord W instance Show W instance Read W instance Bounded W instance Num W instance Real W instance Integral W instance Enum W instance Ix W instance Bits W
word8ToWord16 :: Word8 -> Word16 word8ToWord32 :: Word8 -> Word32 word8ToWord64 :: Word8 -> Word64 word16ToWord8 :: Word16 -> Word8 word16ToWord32 :: Word16 -> Word32 word16ToWord64 :: Word16 -> Word64 word32ToWord8 :: Word32 -> Word8 word32ToWord16 :: Word32 -> Word16 word32ToWord64 :: Word32 -> Word64 word64ToWord8 :: Word64 -> Word8 word64ToWord16 :: Word64 -> Word16 word64ToWord32 :: Word64 -> Word32 word8ToInt :: Word8 -> Int word16ToInt :: Word16 -> Int word32ToInt :: Word32 -> Int word64ToInt :: Word64 -> Int intToWord8 :: Int -> Word8 intToWord16 :: Int -> Word16 intToWord32 :: Int -> Word32 intToWord64 :: Int -> Word64 word64ToInteger :: Word64 -> Integer integerToWord64 :: Integer -> Word64
All arithmetic is performed modulo 2^n One non-obvious consequence of this is that negate should not raise an error on negative arguments.
The coercion wToI converts an unsigned n-bit value to the signed n-bit value with the same representation. For example, word8ToInt8 0xff = -1. Likewise, iToW converts signed n-bit values to the corresponding unsigned n-bit value.
Use Prelude.fromIntegral :: (Integral a, Num b) => a -> b to coerce between different sizes or to preserve sign when converting between values of the same size.
It would be very natural to add a type a type Natural providing an unbounded size unsigned integer—just as Integer provides unbounded size signed integers. We do not do that yet since there is no demand for it. Doing so would require Bits.bitSize to return Maybe Int.
The rules that hold for Enum instances over a bounded type such as Int (see the section of the Haskell 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.
Hugs only provides Eq, Ord, Read and Show instances for Word64 at the moment.