splitmix

Fast Splittable PRNG

LTS Haskell 24.17:0.1.3.1
Stackage Nightly 2025-10-31:0.1.3.1
Latest on Hackage:0.1.3.1

See all snapshots splitmix appears in

BSD-3-Clause licensed
Maintained by Oleg Grenrus
This version can be pinned in stack with:splitmix-0.1.3.1@sha256:d0002f3fb16a2cc5ba8afd47a6657726386edccfe8853d310e3479fe3b45201b,6552

Module documentation for 0.1.3.1

Depends on 2 packages(full list with versions):
base, deepseq

splitmix

Pure Haskell implementation of SplitMix pseudo-random number generator.

dieharder

Dieharder is a random number generator (rng) testing suite. It is intended to test generators, not files of possibly random numbers as the latter is a fallacious view of what it means to be random. Is the number 7 random? If it is generated by a random process, it might be. If it is made up to serve the purpose of some argument (like this one) it is not. Perfect random number generators produce “unlikely” sequences of random numbers – at exactly the right average rate. Testing a rng is therefore quite subtle.

time $(cabal-plan list-bin splitmix-dieharder) splitmix

The test-suite takes around half-an-hour to complete. From 30 runs, 2.49% were weak (3247 passed, 83 weak, 0 failed).

In comparison, built-in Marsenne Twister test takes around 15min.

time dieharder -a

benchmarks

benchmarking list 64/random
time                 1.317 ms   (1.303 ms .. 1.335 ms)
                     0.998 R²   (0.998 R² .. 0.999 R²)
mean                 1.380 ms   (1.365 ms .. 1.411 ms)
std dev              70.83 μs   (37.26 μs .. 131.8 μs)
variance introduced by outliers: 39% (moderately inflated)

benchmarking list 64/tf-random
time                 141.1 μs   (140.4 μs .. 142.1 μs)
                     0.999 R²   (0.998 R² .. 1.000 R²)
mean                 145.9 μs   (144.6 μs .. 150.4 μs)
std dev              7.131 μs   (3.461 μs .. 14.75 μs)
variance introduced by outliers: 49% (moderately inflated)

benchmarking list 64/splitmix
time                 17.86 μs   (17.72 μs .. 18.01 μs)
                     0.999 R²   (0.998 R² .. 1.000 R²)
mean                 17.95 μs   (17.75 μs .. 18.47 μs)
std dev              1.000 μs   (444.1 ns .. 1.887 μs)
variance introduced by outliers: 64% (severely inflated)

benchmarking tree 64/random
time                 800.3 μs   (793.3 μs .. 806.5 μs)
                     0.999 R²   (0.998 R² .. 0.999 R²)
mean                 803.2 μs   (798.1 μs .. 811.2 μs)
std dev              22.09 μs   (14.69 μs .. 35.47 μs)
variance introduced by outliers: 18% (moderately inflated)

benchmarking tree 64/tf-random
time                 179.0 μs   (176.6 μs .. 180.7 μs)
                     0.999 R²   (0.998 R² .. 0.999 R²)
mean                 172.7 μs   (171.3 μs .. 174.6 μs)
std dev              5.590 μs   (4.919 μs .. 6.382 μs)
variance introduced by outliers: 29% (moderately inflated)

benchmarking tree 64/splitmix
time                 51.54 μs   (51.01 μs .. 52.15 μs)
                     0.999 R²   (0.998 R² .. 0.999 R²)
mean                 52.50 μs   (51.93 μs .. 53.55 μs)
std dev              2.603 μs   (1.659 μs .. 4.338 μs)
variance introduced by outliers: 55% (severely inflated)

Note: the performance can be potentially further improved when GHC gets SIMD Support.

Changes

0.1.3.1

  • Fix linking issue symbol not found in flat namespace '_kSecRandomDefault' when using splitmix in TH on macOS.

0.1.3

  • Use system specific entropy/randomess sources to initialise the default generator. Specifically SecRandomCopyBytes on Apple platforms and RtlGenRandom on Windows.

0.1.2

  • Use getentropy for initialisation on unix-like systems (i.e. not Windows).

0.1.1

  • Drop support for GHCs prior 8.6.5
  • Support GHC-9.12

0.1.0.4

  • Add TestU01 test-suite

0.1.0.3

0.1.0.2

  • Drop time dependency in favour of handcoded initialization
    • On Unix platforms we use /dev/urandom if it exists, otherwise use gettimeofday, clock and getpid.
    • On Windows we use GetCurrentProcessID, GetCurrentThreadId(), GetTickCount, GetSystemTime and QueryPerformanceCounter.
    • On GHCJS use Math.random()
    • Using time is a fallback option (e.g. for Hugs).

0.1.0.1

  • Add INLINEABLE pragmas to bitmaskWithRejection* functions
  • Support GHC-9.0

0.1

0.0.5

  • Add nextInteger
  • Use smaller range in bitmaskWithRejection32 and 64, when upper bound is 2^n - 1. This changes generated values when they were on the boundary.

0.0.4

  • Add bitmaskWithRejection32' and bitmaskWithRejection64' which generate numbers in closed range [0, n]. Unticked variants generate in closed-open range [0, n).

0.0.3

  • Add System.Random.SplitMix32 module
  • Add bitmaskWithRejection32 and bitmaskWithRejection64 functions
  • Add nextWord32, nextTwoWord32 and nextFloat
  • Add random flag, dropping dependency on random (breaks things, e.g. QuickCheck, when disabled).

0.0.2

  • Support back to GHC-7.0
  • Add Read SMGen instance

0.0.1