This library provides unsigned integers of various sizes. The types supported are as follows:

type | number of bits |

Word8 | 8 |

Word16 | 16 |

Word32 | 32 |

Word64 | 64 |

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 |

All arithmetic is performed modulo 2^n. One non-obvious 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 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.