Mention existence of 'Natural' in "Data.Word"
[ghc.git] / libraries / base / Data / Word.hs
1 {-# LANGUAGE Safe #-}
2 {-# LANGUAGE NoImplicitPrelude #-}
3
4 -----------------------------------------------------------------------------
5 -- |
6 -- Module : Data.Word
7 -- Copyright : (c) The University of Glasgow 2001
8 -- License : BSD-style (see the file libraries/base/LICENSE)
9 --
10 -- Maintainer : libraries@haskell.org
11 -- Stability : experimental
12 -- Portability : portable
13 --
14 -- Unsigned integer types.
15 --
16 -----------------------------------------------------------------------------
17
18 module Data.Word
19 (
20 -- * Unsigned integral types
21
22 Word,
23 Word8, Word16, Word32, Word64,
24
25 -- * byte swapping
26 byteSwap16, byteSwap32, byteSwap64,
27
28 -- * Notes
29
30 -- $notes
31 ) where
32
33 import GHC.Word
34
35 {- $notes
36
37 * All arithmetic is performed modulo 2^n, where n is the number of
38 bits in the type. One non-obvious consequence of this is that 'Prelude.negate'
39 should /not/ raise an error on negative arguments.
40
41 * For coercing between any two integer types, use
42 'Prelude.fromIntegral', which is specialized for all the
43 common cases so should be fast enough. Coercing word types to and
44 from integer types preserves representation, not sign.
45
46 * An unbounded size unsigned integer type is available with
47 'Numeric.Natural.Natural'.
48
49 * The rules that hold for 'Prelude.Enum' instances over a bounded type
50 such as 'Prelude.Int' (see the section of the Haskell report dealing
51 with arithmetic sequences) also hold for the 'Prelude.Enum' instances
52 over the various 'Word' types defined here.
53
54 * Right and left shifts by amounts greater than or equal to the width
55 of the type result in a zero result. This is contrary to the
56 behaviour in C, which is undefined; a common interpretation is to
57 truncate the shift count to the width of the type, for example @1 \<\<
58 32 == 1@ in some C implementations.
59 -}
60