[Haskell-cafe] What is MonadPlus good for?

[ajb at spamcop.net]

G'day all.

Quoting David Roundy <droundy at abridgegame.org>:

> It might be interesting to write a "backtracking" IO-like monad which
> obeyed m >> mzero === mzero.  I imagine you could do it for something like
> an ACID database, if you define === as meaning "has the same final result
> on the database", which of course would only be useful if the database had
> sufficient locking that it couldn't have been read between the original m
> and the later mzero.

You should talk to the logic programming community about this some time.

As Lee Naish has pointed out on many occasions, it would involve finding a
way to insert the page back into the laser printer and lift the toner off.

Cheers,
Andrew Bromage