by defining the pattern combinators using MonadPlus, you get standard pattern matching with the Maybe
instance of MonadPlus and you get backtracking pattern matching with the [] (list) instance of MonadPlus.
- Mark
On Feb 12, 2005, at 10:08 AM, Benjamin Pierce wrote:
I have seen lots of examples that show how it's useful to make some type
constructor into an instance of Monad.
Where can I find examples showing why it's good to take the trouble to show
that something is also a MonadPlus? (I know there are many examples of
things that *are* MonadPluses; what I want to know is why this is
interesting. :-)
Thanks,
- Benjamin
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