⚠️This is a fork of https://github.com/zinggi/elm-random-pcg-extended ⚠️We do not plan to continue general maintainance of the package and are only publishing it for the purpose of finishing our Elm 0.19 upgrade.
This is a fork, you probably want mgold/elm-random-pcg
Reason of existance
I created this version of the Random library to get more bits of randomness for a random password generator.
For this purpose, I created
Random.Pcg.Extended, which Implements the extended version of PCG.
In the process of doing this, I made the Random library more general, e.g.
Random.General it is now possible to use your own RNG as a base generator.
Random.Pcg for Elm
"The generation of random numbers is too important to be left to chance." – Robert R. Coveyou
An alternate random number generator built around four principles:
Statistical Quality. If you use any seed less than 53,668 and generate one bool, it will be
True– if you're using core's
Randommodule. More sophisticated statistical tests spot patterns in the "random" numbers almost immediately. Would you want to trust the accuracy of your fuzz tests to such a flawed algorithm? This library produces far less predictable and biased output, especially if you use thousands of random numbers. See
test/dieharderfor more details.
Useful features. This library exports
andMap, which are conspicuously absent from core, along with other helpful functions for composing generators. Particularly interesting is
independentSeed, which allows for lazy lists and isolated components to generate as much randomness as they need, when they need it.
Performance. This library will generate floats about 3.5 times faster than core, and ints do not regress. These figures stand to improve pending some optimizations to the compiler. You can see the full benchmark results.
Compatibility. This library is a drop-in replacement for core's Random module. Specifically, you can replace
import Random.Pcg as Randomand everything will continue to work. (The one exception is third party libraries like elm-random-extra.)
This is an implementation of PCG by M. E. O'Neil. The generator is not cryptographically secure.
Please report bugs, feature requests, and other issues on GitHub.
Changelog (major versions only)
- Argument order of
- Upgraded for 0.18.
- Argument order of
- Change implementation to use the RXS-M-SH variant of PCG. Now much faster and not much worse statistically.
initialSeed2, since there are now only 32 bits of state.
Random.Pcg.Interop.fissionhas been changed to a (core) generator of (PCG) seeds.
generateto match core 4.x API. Implemented by Richard Feldman.
- Upgraded for 0.17.
stepto match core 4.x API.
- Module renamed
splithas been removed; use
maxIntvalues changed to match core.