This is a psuedo-random number generator (PRNG). It is designed to
replace the standard Haskell '98 PRNG from the
random package. It
has the following properties:
Nicer API than
random. (Supports all sizes of
Word, for example.)
Much faster than
random. (In my tests, roughly 14x faster.)
Comparable quality to
random. (Both libraries pass the "Die Harder" suite of statistical randomness tests. In other words, neither has any overly obvious pattern to the "random" numbers it produces. Both libraries pass Die Harder with similar scores.)
100% Haskell '98 code. No compiler-specific features. No external dependencies. Builds everywhere.
Pure functions and simple ADTs. No mutable state, no
IOmonad. Simple API.
The actual algorithm is a lag-4 Multiply With Carry (MWC)
generator, using 32-bit arithmetic. (Should be fast on 32-bit and
64-bit platforms.) If my algebra is correct, its period should be
roughly 1.46 * 10^48. (By constrast,
random claims to have a
period of only 2.30 * 10^18.)
Note that this algorithm, by itself, is not cryptographically secure.