src/StdLibExt/RandomExt.icl

   1 implementation module RandomExt
   2
   3 import StdEnvExt
   4 import StdClass, StdInt, StdString
   5 import StdTime
   6
   7
   8 ::      RandomSeed      = RS !Int
   9
  10
  11 nullRandomSeed :: RandomSeed
  12 nullRandomSeed
  13 = RS 0
  14
  15 getNewRandomSeed :: !*env -> (!RandomSeed, !*env) | TimeEnv env
  16 getNewRandomSeed env
  17 # ({hours,minutes,seconds}, env)        = getCurrentTime env
  18 = (RS (1+(hours+minutes+seconds) bitand 65535), env)
  19
  20 random :: !RandomSeed -> (!Int,!RandomSeed)
  21 random (RS seed)
  22 = (newSeed,RS newSeed)
  23 where
  24         newSeed         = if (nextSeed>=0) nextSeed (nextSeed+65537)
  25         nextSeed        = (seed75 bitand 65535)-(seed75>>16)
  26         seed75          = seed*75
  27
  28 instance toString   RandomSeed where toString (RS r)    = toString r
  29 instance fromString RandomSeed where fromString str     = RS (fromString str)
  30 instance ==         RandomSeed where == (RS r1) (RS r2) = r1 == r2