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

ajb at spamcop.net ajb at spamcop.net
Thu Oct 18 23:35:55 EDT 2007


Quoting Stefan O'Rear <stefanor at cox.net>:

> All the MonadPlus I can think of (IO,Maybe,[]) satisfy it.  Were you
> thinking of right distribution?

No monad transformer can satisfy it, because lift m >> mzero is not mzero.

Andrew Bromage

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