2010/4/13 Aaron Sherman <a...@ajs.com>: > On Mon, Apr 12, 2010 at 1:55 PM, Larry Wall <la...@wall.org> wrote: > >> On Mon, Apr 12, 2010 at 07:24:37PM +0200, Moritz Lenz wrote: >> : > 1. do all implementations of Perl6 generate the same sequence, given >> the >> : > same initial seed. >> : >> : I don't think they should. If you want that, use confuse a RNG with a >> : sequence generator that it is not. >> >> While I agree that the default should be non-reproducable, the >> approach taken in Perl 5 is nice to the extent that if you *do* >> seed the built-in RNG with a consistent value, you get a reproducable >> result. And reproducable trees of random sequences can be generated >> by controlling the seeds of each node in the tree. >> > > I think that what this conversation is boiling down to is: an RNG is just a > role that wraps an iterator factory and provides some passable defaults, to > be implemented as the default class or classes for Perl's core. That's fine, > but the idea of non-reproducible defaults worries me. If, by this, you mean > that whatever seed is provided to "srand" is to be aggregated with another > source (e.g. XORed with output from the system's entropy source), then I > would love to hear from someone who has experience with the last 10 years of > PRNG work who thinks that's not opening us up to some sort of strange > edge-case risk. > > PRNGs are often misrepresented as frivolous, but as I'm sure you know from > your work at JPL, high quality random sequences are much-prized, and any > language that starts off with some poor assumptions will ultimately pay for > it. > > Some good reading for recent work: > > http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/
MT19937 was ported on Parrot/PIR (currently hosted on http://github.com/fperrad/parrot-MT19937). But currently, Parrot lacks an entropy source. François > http://eprint.iacr.org/2006/086 > http://lcamtuf.coredump.cx/oldtcp/tcpseq.html > http://www.avatar.se/python/crng/index.html > > -- > Aaron Sherman > Email or GTalk: a...@ajs.com > http://www.ajs.com/~ajs >
