deriving-compat-0.4.3: Backports of GHC deriving extensions

Data.Functor.Deriving

Description

Exports functions to mechanically derive Functor instances.

For more info on how deriving Functor works, see this GHC wiki page.

Synopsis

# Functor

Generates a Functor instance declaration for the given data type or data family instance.

Like deriveFunctor, but takes an FFTOptions argument.

Generates a lambda expression which behaves like fmap (without requiring a Functor instance).

Like makeFmap, but takes an FFTOptions argument.

# FFTOptions

newtype FFTOptions Source #

Options that further configure how the functions in Data.Functor.Deriving should behave. (FFT stands for 'Functor'/'Foldable'/'Traversable'.)

Constructors

 FFTOptions FieldsfftEmptyCaseBehavior :: BoolIf True, derived instances for empty data types (i.e., ones with no data constructors) will use the EmptyCase language extension. If False, derived instances will simply use seq instead. (This has no effect on GHCs before 7.8, since EmptyCase is only available in 7.8 or later.)

Instances

 Source # Methods Source # Methods Source # Methods Source # MethodsshowList :: [FFTOptions] -> ShowS #

Conservative FFTOptions that doesn't attempt to use EmptyCase (to prevent users from having to enable that extension at use sites.)

# deriveFunctor limitations

Be aware of the following potential gotchas:

• Type variables of kind * -> * are assumed to have Functor constraints. If this is not desirable, use makeFmap.