[Haskell-cafe] Re: [Haskell] Announce: generating free theorems, online and offline

David Menendez dave at zednenem.com
Thu Oct 18 20:39:04 EDT 2007

On 10/18/07, Stefan O'Rear <stefanor at cox.net> wrote:
> On Thu, Oct 18, 2007 at 03:36:01AM -0400, ajb at spamcop.net wrote:
> > (As an aside: The H98 report still list the right-zero law as being
> > a law for MonadPlus, even though most MonadPlus instances don't obey
> > it.  That's actually a defect in the report.)
> All the MonadPlus I can think of (IO,Maybe,[]) satisfy it.  Were you
> thinking of right distribution?

"print 1 >> mzero" returns the same result as "mzero" (i.e., it throws
an exception), but it has different effects.

Dave Menendez <dave at zednenem.com>

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