Proposal: Applicative => Monad: Call for consensus

[Tyson Whitehead]

On January 4, 2011 07:25:36 Ian Lynagh wrote:
> Have you got an example of a Monad for which you'd want to define join
> but not (>>=)?
> 
> >     (>>) :: forall a b. m a -> m b -> m b
> >     (>>) = (*>)
> >     
> >     return :: a -> m a
> >     return = pure
> >     
> >     fail :: String -> m a
> >     fail s = error s
> > 
> > 2) Make 'join' a method of Monad.
> 
> Why?

It seems to me that while join is more of a value transformer as apposed to a 
flow combining operator, which makes it fit in better with the rest applicative.

That is,

(<*>) :: f (a -> b) -> f a -> f b  -- (<*>) f -- transforms f
join :: f (f a) -> f a  -- join y -- transforms y
return :: a -> f a -- return x -- transforms x

Cheers!  -Tyson