[Haskell-cafe] What is MonadPlus good for?

Mark Tullsen tullsen at galois.com
Mon Feb 14 15:03:53 EST 2005

Here's an example:  In my paper "First Class Patterns" 
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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