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

[Stefan O'Rear]

On Thu, Oct 18, 2007 at 08:39:04PM -0400, David Menendez wrote:
> 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.

Oh, hehe.  I thought you meant print 1 `mappend` mzero being equal to
print 1.

Oops.

Stefan
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