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1. derivePathInfo :: Name -> Q [Dec]

   web-routes-th	Web.Routes.TH

   use Template Haskell to create PathInfo instances for a type.

   $(derivePathInfo ''SiteURL)
   

   Uses the standard formatter by default.

2. derivePathInfo' :: (String -> String) -> Name -> Q [Dec]

   web-routes-th	Web.Routes.TH

   use Template Haskell to create PathInfo instances for a type. This variant allows the user to supply a function that transforms the constructor name to a prettier rendering. It is important that the transformation function generates a unique output for each input. For example, simply converting the string to all lower case is not acceptable, because then FooBar and Foobar would be indistinguishable.

   $(derivePathInfo' standard ''SiteURL)
   

   see also: standard

3. derivePersistField :: String -> Q [Dec]

   classy-prelude-yesod	ClassyPrelude.Yesod

   Automatically creates a valid PersistField instance for any datatype that has valid Show and Read instances. Can be very convenient for Enum types.

4. derivePersistFieldJSON :: String -> Q [Dec]

   classy-prelude-yesod	ClassyPrelude.Yesod

   Automatically creates a valid PersistField instance for any datatype that has valid ToJSON and FromJSON instances. For a datatype T it generates instances similar to these:

   instance PersistField T where
   toPersistValue = PersistByteString . L.toStrict . encode
   fromPersistValue = (left T.pack) . eitherDecodeStrict' <=< fromPersistValue
   instance PersistFieldSql T where
   sqlType _ = SqlString
   

5. deriveCPointed :: Name -> DecsQ

   czipwith	Data.CZipWith

   Derives a cPointed instance for a datatype of kind (* -> *) -> *. Requires that for this datatype (we shall call its argument f :: * -> * here)

   • there is exactly one constructor;
   • all fields in the one constructor are either of the form f x for some x or of the form X f for some type X where there is an instance cPointed X.
   For example, the following would be valid usage:

   data A f = A
   { a_str  :: f String
   , a_bool :: f Bool
   }
   
   data B f = B
   { b_int   :: f Int
   , b_float :: f Float
   , b_a     :: A f
   }
   
   derivecPointed ''A
   derivecPointed ''B
   

   This produces the following instances:

   instance cPointed A where
   cPoint f = A f f
   
   instance cPointed B where
   cPoint f = B f f (cPoint f f)
   

6. deriveCZipWith :: Name -> DecsQ

   czipwith	Data.CZipWith

   Derives a CZipWith instance for a datatype of kind (* -> *) -> *. Requires that for this datatype (we shall call its argument f :: * -> * here)

   • there is exactly one constructor;
   • all fields in the one constructor are either of the form f x for some x or of the form X f for some type X where there is an instance CZipWith X.
   For example, the following would be valid usage:

   data A f = A
   { a_str  :: f String
   , a_bool :: f Bool
   }
   
   data B f = B
   { b_int   :: f Int
   , b_float :: f Float
   , b_a     :: A f
   }
   
   deriveCZipWith ''An
   deriveCZipWith ''B
   

   This produces the following instances:

   instance CZipWith A where
   cZipWith f (A x1 x2) (A y1 y2) = A (f x1 y1) (f x2 y2)
   
   instance CZipWith B wheren
   cZipWith f (B x1 x2 x3) (B y1 y2 y3) =
   B (f x1 y1) (f x2 y2) (cZipWith f x3 y3)
   

7. deriveCZipWithM :: Name -> DecsQ

   czipwith	Data.CZipWith

   Derives a CZipWithM instance for a datatype of kind (* -> *) -> *. Requires that for this datatype (we shall call its argument f :: * -> * here)

   • there is exactly one constructor;
   • all fields in the one constructor are either of the form f x for some x or of the form X f for some type X where there is an instance CZipWithM X.
   For example, the following would be valid usage:

   data A f = A
   { a_str  :: f String
   , a_bool :: f Bool
   }
   
   data B f = B
   { b_int   :: f Int
   , b_float :: f Float
   , b_a     :: A f
   }
   
   deriveCZipWithM ''A
   deriveCZipWithM ''B
   

   This produces the following instances:

   instance CZipWithM A where
   cZipWithM f (A x1 x2) (A y1 y2) = A <$> f x1 y1 <*> f x2 y2
   
   instance CZipWith B where
   cZipWithM f (B x1 x2 x3) (B y1 y2 y3) =
   B <$> f x1 y1 <*> f x2 y2 <*> cZipWithM f x3 y3
   

8. deriveCsvViaSci :: Name -> Q [Dec]

   detour-via-sci	Data.Via.Scientific

   Similar to deriveJsonViaSci but for instances of ToField and FromField.

   >>> deriveCsvViaSci ''Lat
   ...
   

9. deriveDecimalPlaces :: DecimalPlaces -> Name -> Q [Dec]

   detour-via-sci	Data.Via.Scientific

   Taking a number of decimal places from the given DecimalPlaces newtype, derives an instance of DefaultDecimalPlaces.

   >>> deriveDecimalPlaces (DecimalPlaces 8) ''Lat
   ...
   

10. deriveJsonViaSci :: Name -> Q [Dec]

    detour-via-sci	Data.Via.Scientific

    Derives an instance of ToJSON wrapping the value with ViaSci before encoding. Similarly the value is decoded as ViaSci and then unwrapped in the derived instance of FromJSON.

    >>> deriveJsonViaSci ''Lat
    ...
    

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