Data.Functor.Deriving

Exports functions to mechanically derive Functor instances.

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

Functor

deriveFunctor :: Name -> Q [Dec]

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

deriveFunctorOptions :: FFTOptions -> Name -> Q [Dec]

Like deriveFunctor, but takes an FFTOptions argument.

makeFmap :: Name -> Q Exp

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

makeFmapOptions :: FFTOptions -> Name -> Q Exp

Like makeFmap, but takes an FFTOptions argument.

FFTOptions

newtype FFTOptions

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

Constructors

FFTOptions

Fields

• fftEmptyCaseBehavior :: Bool

  If 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

Eq FFTOptions

Defined in Data.Functor.Deriving.Internal

Methods

(==) :: FFTOptions -> FFTOptions -> Bool

(/=) :: FFTOptions -> FFTOptions -> Bool

Ord FFTOptions

Defined in Data.Functor.Deriving.Internal

Methods

compare :: FFTOptions -> FFTOptions -> Ordering

(<) :: FFTOptions -> FFTOptions -> Bool

(<=) :: FFTOptions -> FFTOptions -> Bool

(>) :: FFTOptions -> FFTOptions -> Bool

(>=) :: FFTOptions -> FFTOptions -> Bool

max :: FFTOptions -> FFTOptions -> FFTOptions

min :: FFTOptions -> FFTOptions -> FFTOptions

Read FFTOptions

Defined in Data.Functor.Deriving.Internal

Methods

readsPrec :: Int -> ReadS FFTOptions

readList :: ReadS [FFTOptions]

readPrec :: ReadPrec FFTOptions

readListPrec :: ReadPrec [FFTOptions]

Show FFTOptions

Defined in Data.Functor.Deriving.Internal

Methods

showsPrec :: Int -> FFTOptions -> ShowS

show :: FFTOptions -> String

showList :: [FFTOptions] -> ShowS

defaultFFTOptions :: FFTOptions

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.