src/Game/randomstream.dcl

   1 definition module randomstream
   2
   3 /**     This module implements a number of infinite random streams.
   4         For predictable games, the onesStream can be used.
   5 */
   6 import StdClass
   7 import StdMaybe
   8 import RandomExt
   9
  10 ::      Stream a                                :== [a]                 // an infinite list of random values
  11 ::      P                                               :== Real                // 0<=x<=1.0
  12
  13 /**     intRandomStream
  14                 creates a stream of random (positive and negative) Integer values.
  15         realRandomStream
  16                 creates a stream of random (positive and negative) Real values.
  17         boolRandomStream
  18                 creates a stream of random Bool values.
  19         probabilityRandomStream
  20                 creates a stream of random P values.
  21         onesStream
  22                 creates a stream of one values.
  23 */
  24 intRandomStream                         :: !RandomSeed -> Stream Int
  25 realRandomStream                        :: !RandomSeed -> Stream Real
  26 boolRandomStream                        :: !RandomSeed -> Stream Bool
  27 probabilityRandomStream         :: !RandomSeed -> Stream P
  28 onesStream                                      ::                Stream P
  29
  30 /**     nextRandom<Type> creates a next pseudo random value of given type.
  31 */
  32 nextRandomInt                           :: !RandomSeed -> .(!Int, !RandomSeed)
  33 nextRandomReal                          :: !RandomSeed -> .(!Real,!RandomSeed)
  34 nextRandomBool                          :: !RandomSeed -> .(!Bool,!RandomSeed)
  35 nextRandomP                                     :: !RandomSeed -> .(!P,   !RandomSeed)
  36 next1                                           :: !RandomSeed -> .(!P,   !RandomSeed)
  37
  38 /** make the random realistic, as in, small errors occur more often:
  39                 \r -> 1.0-r^4 (zero <= r <= 1.0)
  40 */
  41 makeRandomRealistic                     :: !P -> P
  42 //              \r -> 1-r^10
  43 makeRandomRealisticSkilled      :: !P -> P
  44
  45 /** selectMostProbableAction randomly selects one of the elements of the list that have the same
  46         highest probability.
  47         If all probabilities are equal to zero, then Nothing is returned.
  48 */
  49 selectMostProbableAction        :: ![(P,a)] !RandomSeed -> (!Maybe a,!RandomSeed)