1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
|
{-# language BangPatterns #-}
{-# language ViewPatterns #-}
module KWay.RandomIncreasing where
import System.Random
import Data.Word
import Data.List (unfoldr)
data Stream = Stream !Word64 {-# UNPACK #-} !StdGen
viewStream :: Stream -> (Word64, Stream)
viewStream (Stream w gen) = (w, case uniform gen of (k, gen') -> Stream (w + fromIntegral (k :: Word16)) gen')
mkStream :: StdGen -> (Stream, StdGen)
mkStream gen
| (gen1, gen2) <- split gen
, (w16, gen1') <- uniform gen1
= (Stream (fromIntegral (w16 :: Word16)) gen1', gen2)
mkStreams :: Int -> StdGen -> [Stream]
mkStreams !n !gen
| n <= 0 = []
| (s, gen') <- mkStream gen
= s : mkStreams (n - 1) gen'
|
