ctm:
> Indeed it can. Ignoring conventional wisdom about dirty linen, here are
> idiom brackets
>
> > class Applicative i => Idiomatic i f g | g -> f i where
> > idiomatic :: i f -> g
>
> > iI :: Idiomatic i f g => f -> g
> > iI = idiomatic . pure
>
> > data Ii = Ii
>
> > instance Applicative i => Idiomatic i x (Ii -> i x) where
> > idiomatic xi Ii = xi
> > instance Idiomatic i f g => Idiomatic i (s -> f) (i s -> g) where
> > idiomatic sfi si = idiomatic (sfi <*> si)
>
> So that
>
> iI f x y Ii = f <$> x <*> y
>
> Now add
>
> > data Ji = Ji
>
> > instance (Monad i, Applicative i) => Idiomatic i (i x) (Ji -> i
> x) where
> > idiomatic xii Ji = join xii
>
> and you've got
>
> iI f x y Ji = join $ f <$> x <*> y
Very nice! Just so we don't forget this, I created a wiki page,
http://haskell.org/haskellwiki/Idiom_brackets
-- Don
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