[Haskell-cafe] Re: [Haskell] [ANN] Safe Lazy IO in Haskell

[Jason Dusek]

2009/05/18 Miguel Mitrofanov <miguelimo38 at yandex.ru>:
> On 19 May 2009, at 09:06, Ryan Ingram wrote:
>
>> This is a common problem with trying to use do-notation; there are
>> some cases where you can't make the object an instance of Monad.  The
>> same problem holds for Data.Set; you'd can write
>>
>> setBind :: Ord b => Set a -> (a -> Set b) -> Set b
>> setBind m f = unions (map f $ toList m)
>>
>> but there is no way to use setBind for a definition of >>=
>
> You can use a continuation trick.

  Trick?

--
Jason Dusek