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Unsigned integral types
Unsigned integer types.
data Word
data Word8
data Word16
data Word32
data Word64
Unsigned integral types
data Word Source
A Word is an unsigned integral type, with the same size as Int.
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data Word8 Source
8-bit unsigned integer type
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data Word16 Source
16-bit unsigned integer type
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data Word32 Source
32-bit unsigned integer type
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data Word64 Source
64-bit unsigned integer type
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  • All arithmetic is performed modulo 2^n, where n is the number of bits in the type. One non-obvious consequence of this is that Prelude.negate should not raise an error on negative arguments.
  • For coercing between any two integer types, use Prelude.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 Prelude.Integer provides unbounded size signed integers. We do not do that yet since there is no demand for it.
  • The rules that hold for Prelude.Enum instances over a bounded type such as Prelude.Int (see the section of the Haskell report dealing with arithmetic sequences) also hold for the Prelude.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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