Efficient MT19937 (standard 32-bit Mersenne Twister PRNG) implementation, in pure Haskell (no FFI) with a pure interface.
Only the PRNG itself is implemented. If you'd like to use this as a PRNG in any capacity, you'll need to wrap it into some monad or some such.
Doesn't seem too useful? You'd be surprised. This was originally written while decoding a file header which was bafflingly encoded using a set-seed MT19937.
Provided under the MIT license. See LICENSE for license text.