Add voidM to Control.Monad

Erik Hesselink hesselink at
Mon Jan 16 16:22:16 CET 2012

2012/1/16 Simon Hengel <sol at>:
>> voidM :: Monad m => m a -> m ()
>> voidM m = m >> return ()
> Is voidM meant to be used with instance of Monad that are no monads, and
> hence have no Functor instance (like HtmlM[1])?

You could easily implement a Functor instance for this type, since it
would mirror the instance for `Const a` [2], i.e. only change the type
parameter, and otherwise be the identity function.



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