"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 53668 and generate one bool, it will be True – if you're
using the core library. This library produces far less predictable output, especially if you use thousands of random
numbers. The core library fails after as little as five seconds of scrutiny. Would you want to trust the accuracy of
your fuzz tests to such a flawed algorithm? See
test/dieharder for more details.
Useful features. This library exports constant and andMap, which are conspicuously absent from core, along with
other helpful functions for composing generators. Especially interesting is the independentSeed function which allows
for lazy lists and isolated components to generate as much randomness as they need, when they need it. There is also a
fastForward function that allows random access (rather than sequential access) into, effectively, an infinite array of
random numbers. This can be used instead of reading a finite amount of random values into a large data structure.
Performace. 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 forcore's Random module. Specifically, you
can replace import Random with import Random.Pcg as Random and everything will continue to work. The exception is third party
libraries like elm-random-extra);
the long-term resolution is to pull this library into core.
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.
initialSeed2, since there are now only 32 bits of state.Random.Pcg.Interop.fission has been changed to a (core) generator of (PCG) seeds.generate to match core 4.x API. Implemented by Richard Feldman.generate renamed step to match core 4.x API.Random.Pcg from Random.PCG.split has been removed; use independentSeed.minInt and maxInt values changed to match core.