[plt-scheme] Does SRFI-27 specify repeatable PRNGs?

Erich Rast wrote:
> Hi,
>
> Sorry, I know this is a bit off-topic, but perhaps someone here has 
> already stumbled across the answer. I'm looking for a good PRNG that 
> is portable, but it needs to be one that allows me to get exactly the 
> same PRN sequence from the same seed.
>
> Can I use SRFI-27 for that purpose or does it only specify the 
> interface to possibly different PRNGs that might produce different 
> sequences?
>

SRFI-27 only specifies the interface to possibly different PRNGs that 
might produce different sequences. But the reference implementation of 
SRFI 27 is portable and allows you to get exactly the same PRN sequence 
from the same seed.

> How about the built-in generator of MzScheme, might it change in 
> future or is it part of the specs that it won't change under the hood?
>

Matthew just changed the built-in generator of MzScheme, as a result of 
a discussion here a few days ago. The SRFI 27 implementation in SVN 
(v399) is build on top of the built-in generator, and produces the same 
sequence as the reference implementation of SRFI 27.

> Best,
>
> Erich
>
Chongkai