Add flipped fmap

Bas van Dijk v.dijk.bas at
Thu Apr 8 16:07:52 EDT 2010

On Thu, Apr 8, 2010 at 9:38 PM, Isaac Dupree
> This parallelism also suggests to me that <$$> should be placed (only) in
> Control.Applicative, which is where <*>, <$>, and <**> reside.  Yeah, I know
> that's annoying...

That's indeed annoying.

What about removing <$> and <$ from Control.Applicative?

One advantage is that this reduces the complexity tax of Control.Applicative.

One disadvantage is that this will surely break some code. Especially
because, for some weird reason, Data.Functor is not know to hoogle.

And <$> is reported to be only exported by Control.Applicative


Let's save this for a new proposal however...


Jonathan, thanks for the equational law relating <$$> and <**>:
a <$$> f = a <**> return f
this has strongly put me back in the +1 camp :-)

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