pcgen

A fast pseudorandom number generator, as presented by M.E. O'Neill on http://www.pcg-random.org. See that site for information on the particulars of the technique used.

This implementation uses two Word64 of internal data and produces a Word32 of output per step. It's two to three times as fast as StdGen.

The generator implements the RandomGen typeclass from the random package, but also provides its step function as a stand alone function that you can use without the typeclass.