# Ticket #4314: SplittableGenClass.patch

File SplittableGenClass.patch, 3.2 KB (added by , 7 years ago) |
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1 | 1 patch for repository http://darcs.haskell.org/packages/random: |

2 | |

3 | Tue Sep 14 16:29:45 PDT 2010 thomas.dubuisson@gmail.com |

4 | * Move "split" into its own class |

5 | |

6 | New patches: |

7 | |

8 | [Move "split" into its own class |

9 | thomas.dubuisson@gmail.com**20100914232945 |

10 | Ignore-this: 588e2a321823c206962b77c12cdb652a |

11 | ] { |

12 | hunk ./System/Random.hs 43 |

13 | |

14 | -- * Random number generators |

15 | |

16 | - RandomGen(next, split, genRange) |

17 | + RandomGen(next, genRange) |

18 | + , SplittableGen(split) |

19 | |

20 | -- ** Standard random number generators |

21 | , StdGen |

22 | hunk ./System/Random.hs 105 |

23 | -- | The class 'RandomGen' provides a common interface to random number |

24 | -- generators. |

25 | -- |

26 | --- Minimal complete definition: 'next' and 'split'. |

27 | +-- Minimal complete definition: 'next'. |

28 | |

29 | class RandomGen g where |

30 | |

31 | hunk ./System/Random.hs 114 |

32 | -- and a new generator. |

33 | next :: g -> (Int, g) |

34 | |

35 | - -- |The 'split' operation allows one to obtain two distinct random number |

36 | - -- generators. This is very useful in functional programs (for example, when |

37 | - -- passing a random number generator down to recursive calls), but very |

38 | - -- little work has been done on statistically robust implementations of |

39 | - -- 'split' (["System.Random\#Burton", "System.Random\#Hellekalek"] |

40 | - -- are the only examples we know of). |

41 | - split :: g -> (g, g) |

42 | - |

43 | -- |The 'genRange' operation yields the range of values returned by |

44 | -- the generator. |

45 | -- |

46 | hunk ./System/Random.hs 136 |

47 | -- default method |

48 | genRange _ = (minBound, maxBound) |

49 | |

50 | +-- | The class 'SplittableGen' proivides a way to specify a random number |

51 | +-- generator that can be split into two new generators. |

52 | +class SplittableGen g where |

53 | + -- |The 'split' operation allows one to obtain two distinct random number |

54 | + -- generators. This is very useful in functional programs (for example, when |

55 | + -- passing a random number generator down to recursive calls), but very |

56 | + -- little work has been done on statistically robust implementations of |

57 | + -- 'split' (["System.Random\#Burton", "System.Random\#Hellekalek"] |

58 | + -- are the only examples we know of). |

59 | + split :: g -> (g, g) |

60 | + |

61 | {- | |

62 | The 'StdGen' instance of 'RandomGen' has a 'genRange' of at least 30 bits. |

63 | |

64 | hunk ./System/Random.hs 178 |

65 | |

66 | instance RandomGen StdGen where |

67 | next = stdNext |

68 | - split = stdSplit |

69 | genRange _ = stdRange |

70 | |

71 | hunk ./System/Random.hs 180 |

72 | +instance SplittableGen StdGen where |

73 | + split = stdSplit |

74 | + |

75 | instance Show StdGen where |

76 | showsPrec p (StdGen s1 s2) = |

77 | showsPrec p s1 . |

78 | } |

79 | |

80 | Context: |

81 | |

82 | [Fix randomIvalDouble so that it will not produce values more than a few ULPs below the requested lower bound |

83 | James Cook <james.cook@usma.edu>**20100412132638 |

84 | Ignore-this: 35a65dae123bbf5f812ebd0aac7aa3b1 |

85 | ] |

86 | [Bump version to 1.0.0.2 |

87 | Ian Lynagh <igloo@earth.li>**20090920141953] |

88 | [use explicit import list for Data.Sequence, in preparation for an expanded interface |

89 | Ross Paterson <ross@soi.city.ac.uk>**20090913230910 |

90 | Ignore-this: d6f37ea56cff7c7f4edcafb89b2a9f |

91 | ] |

92 | [Fix "Cabal check" warnings |

93 | Ian Lynagh <igloo@earth.li>**20090811215920] |

94 | [change dependency from old-time to time |

95 | Laszlo Nagy <rizsotto@gmail.com>**20090709091417 |

96 | Ignore-this: de203b243bd2f4035661c91971bd49cc |

97 | ] |

98 | [TAG 2009-06-25 |

99 | Ian Lynagh <igloo@earth.li>**20090625160406] |

100 | Patch bundle hash: |

101 | aec6bb01fa1395034c0bf0c74b6bb8806922e3de |