Text.Show.Deriving

Exports functions to mechanically derive Show, Show1, and Show2 instances. Note that upstream GHC does not have the ability to derive Show1 or Show2 instances, but since the functionality to derive Show extends very naturally Show1 and Show2, the ability to derive the latter two classes is provided as a convenience.

Show

deriveShow :: Name -> Q [Dec]

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

deriveShowOptions :: ShowOptions -> Name -> Q [Dec]

Like deriveShow, but takes a ShowOptions argument.

makeShowsPrec :: Name -> Q Exp

Generates a lambda expression which behaves like showsPrec (without requiring a ShowClass instance).

makeShowsPrecOptions :: ShowOptions -> Name -> Q Exp

Like makeShowsPrec, but takes a ShowOptions argument.

makeShow :: Name -> Q Exp

Generates a lambda expression which behaves like show (without requiring a ShowClass instance).

makeShowOptions :: ShowOptions -> Name -> Q Exp

Like makeShow, but takes a ShowOptions argument.

makeShowList :: Name -> Q Exp

Generates a lambda expression which behaves like showList (without requiring a ShowClass instance).

makeShowListOptions :: ShowOptions -> Name -> Q Exp

Like makeShowList, but takes a ShowOptions argument.

Show1

deriveShow1 :: Name -> Q [Dec]

Generates a Show1 instance declaration for the given data type or data family instance.

deriveShow1Options :: ShowOptions -> Name -> Q [Dec]

Like deriveShow1, but takes a ShowOptions argument.

makeLiftShowsPrec :: Name -> Q Exp

Generates a lambda expression which behaves like liftShowsPrec (without requiring a Show1 instance).

This function is not available with transformers-0.4.

makeLiftShowsPrecOptions :: ShowOptions -> Name -> Q Exp

Like makeLiftShowsPrec, but takes a ShowOptions argument.

This function is not available with transformers-0.4.

makeLiftShowList :: Name -> Q Exp

Generates a lambda expression which behaves like liftShowList (without requiring a ShowClass instance).

This function is not available with transformers-0.4.

makeLiftShowListOptions :: ShowOptions -> Name -> Q Exp

Like makeLiftShowList, but takes a ShowOptions argument.

This function is not available with transformers-0.4.

makeShowsPrec1 :: Name -> Q Exp

Generates a lambda expression which behaves like showsPrec1 (without requiring a Show1 instance).

makeShowsPrec1Options :: ShowOptions -> Name -> Q Exp

Like makeShowsPrec1, but takes a ShowOptions argument.

Show2

deriveShow2 :: Name -> Q [Dec]

Generates a Show2 instance declaration for the given data type or data family instance.

This function is not available with transformers-0.4.

deriveShow2Options :: ShowOptions -> Name -> Q [Dec]

Like deriveShow2, but takes a ShowOptions argument.

This function is not available with transformers-0.4.

makeLiftShowsPrec2 :: Name -> Q Exp

Generates a lambda expression which behaves like liftShowsPrec2 (without requiring a Show2 instance).

This function is not available with transformers-0.4.

makeLiftShowsPrec2Options :: ShowOptions -> Name -> Q Exp

Like makeLiftShowsPrec2, but takes a ShowOptions argument.

This function is not available with transformers-0.4.

makeLiftShowList2 :: Name -> Q Exp

Generates a lambda expression which behaves like liftShowList2 (without requiring a ShowClass instance).

This function is not available with transformers-0.4.

makeLiftShowList2Options :: ShowOptions -> Name -> Q Exp

Like makeLiftShowList2, but takes a ShowOptions argument.

This function is not available with transformers-0.4.

makeShowsPrec2 :: Name -> Q Exp

Generates a lambda expression which behaves like showsPrec2 (without requiring a Show2 instance).

This function is not available with transformers-0.4.

makeShowsPrec2Options :: ShowOptions -> Name -> Q Exp

Like makeShowsPrec2, but takes a ShowOptions argument.

This function is not available with transformers-0.4.

ShowOptions

data ShowOptions

Options that further configure how the functions in Text.Show.Deriving should behave.

Constructors

ShowOptions

Fields

• ghc8ShowBehavior :: Bool

  If True, the derived ShowClass, Show1, or Show2 instance will not surround the output of showing fields of unlifted types with parentheses, and the output will be suffixed with hash signs (#).

• showEmptyCaseBehavior :: 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

Read ShowOptions

Defined in Text.Show.Deriving.Internal

Methods

readsPrec :: Int -> ReadS ShowOptions

readList :: ReadS [ShowOptions]

readPrec :: ReadPrec ShowOptions

readListPrec :: ReadPrec [ShowOptions]

Show ShowOptions

Defined in Text.Show.Deriving.Internal

Methods

showsPrec :: Int -> ShowOptions -> ShowS

show :: ShowOptions -> String

showList :: [ShowOptions] -> ShowS

Eq ShowOptions

Defined in Text.Show.Deriving.Internal

Methods

(==) :: ShowOptions -> ShowOptions -> Bool

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

Ord ShowOptions

Defined in Text.Show.Deriving.Internal

Methods

compare :: ShowOptions -> ShowOptions -> Ordering

(<) :: ShowOptions -> ShowOptions -> Bool

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

(>) :: ShowOptions -> ShowOptions -> Bool

(>=) :: ShowOptions -> ShowOptions -> Bool

max :: ShowOptions -> ShowOptions -> ShowOptions

min :: ShowOptions -> ShowOptions -> ShowOptions

defaultShowOptions :: ShowOptions

ShowOptions that match the behavior of the most recent GHC release.

legacyShowOptions :: ShowOptions

ShowOptions that match the behavior of the installed version of GHC.

deriveShow limitations

Be aware of the following potential gotchas:

• Type variables of kind * are assumed to have Show constraints. Type variables of kind * -> * are assumed to have Show1 constraints. Type variables of kind * -> * -> * are assumed to have Show2 constraints. If this is not desirable, use makeShowsPrec or one of its cousins.
• The Show1 class had a different definition in transformers-0.4, and as a result, deriveShow1 implements different instances for the transformers-0.4 Show1 than it otherwise does. Also, makeLiftShowsPrec and makeLiftShowList are not available when this library is built against transformers-0.4, only 'makeShowsPrec1.
• The Show2 class is not available in transformers-0.4, and as a result, neither are Template Haskell functions that deal with Show2 when this library is built against transformers-0.4.