[Haskell-cafe] How unique is Unique

Andrew Butterfield andrew.butterfield at cs.tcd.ie
Fri May 27 10:29:39 CEST 2011

On 27 May 2011, at 08:35, Emil Axelsson wrote:

> Hello!
> Lacking a proper blog, I've written some notes about Data.Unique here:
>  http://community.haskell.org/~emax/darcs/MoreUnique/
> This describes a real problem that makes Data.Unique unsuitable for implementing observable sharing.

Looking at the source for Data.Unique shows that its implemented as an Integer, starting at 0,
when the IO monad is started - so the values are only unique within a single I/O run,
and are definitely not comparable across runs...
> The document also proposes a solution that uses time stamps to generate symbols that are "more unique".
> Does anyone have any comments on the proposed solution? Are there any alternatives available?

I haven't had time to look at that part yet ....
> Thanks!
> / Emil
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
> http://www.haskell.org/mailman/listinfo/haskell-cafe

Andrew Butterfield     Tel: +353-1-896-2517     Fax: +353-1-677-2204
Foundations and Methods Research Group Director.
School of Computer Science and Statistics,
Room F.13, O'Reilly Institute, Trinity College, University of Dublin

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/haskell-cafe/attachments/20110527/365d4c27/attachment.htm>

More information about the Haskell-Cafe mailing list