
Data.Word  Portability  portable  Stability  experimental  Maintainer  libraries@haskell.org 





Description 
Unsigned integer types.


Synopsis 




Unsigned integral types


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


data Word8 
8bit unsigned integer type
 Instances  


data Word16 
16bit unsigned integer type
 Instances  


data Word32 
32bit unsigned integer type
 Instances  


data Word64 
64bit unsigned integer type
 Instances  


Notes


 All arithmetic is performed modulo 2^n, where n is the number of
bits in the type. One nonobvious consequence of this is that negate
should not raise an error on negative arguments.
 For coercing between any two integer types, use
fromIntegral, which is specialized for all the
common cases so should be fast enough. Coercing word types to and
from integer types preserves representation, not sign.
 It would be very natural to add 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.
 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.


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