Functor => Pointed => Applicative => Monad

Tyson Whitehead twhitehead at
Mon Nov 29 17:00:56 CET 2010

On November 29, 2010 08:58:41 Maciej Piechotka wrote:
> Probably it is because that the Monad is in core of many Haskell
> libraries from which some do not define Applicative. Possibly it could
> be tested on Hackage how big impact would be to current packages.

This shouldn't really be a show stopper though.  If you have the code to 
generate the Monad instance, you already have your Applicative instance

f <*> x = do { f' <- f; x' <- x; return $ f x }

Presumably, if you wanted to make this change (which I also think is a good 
idea), you would go through and patch the packages missing this instance first.

Cheers!  -Tyson
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