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# Derived Instances
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Automatic derivation of instances is jolly useful. Current problems are:
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- Automatic derivation is only available for certain classes defined in the Prelude and standard libraries.
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- There is no way to specify how to derive a user-defined class in the general case.
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- Even in the absence of user-defined deriving, it should be easy for a 'newtype' decl to inherit some of the instances of its parent type, no matter where the class was defined, but this is currently only available as a ghc extension to haskell'98.
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There are various extant proposals to enable the user-specification of the derivation of class instances.
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- fill out a list |
