Applicative/Monad proposal related warnings (AMP phase 1)

Add ad-hoc warnings to GHC telling the user about the following:[[BR]]

• Instance of Monad without instances of Functor/Applicative[[BR]]
• Instance of MonadPlus without instance of Alternative[[BR]]
• Module defines functions named (<*>), pure or join

Refactoring code to remove these warnings makes sure the AMP will not break the module in the future. Since they are basically meta-deprecations, I would suggest treating them similar to ordinary deprecations.

This is part of phase 1 of the Applicative/Monad proposal (AMP), as discussed on the mailing lists [1]; a more detailed description of the AMP is available on the Wiki [2].

[1]: http://article.gmane.org/gmane.comp.lang.haskell.libraries/19482 [2]: http://www.haskell.org/haskellwiki/Functor-Applicative-Monad_Proposal

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Trac field	Value
Version	7.6.3
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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