| Safe Haskell | Safe-Inferred |
|---|---|
| Language | Haskell2010 |
Text.Show.Combinators
Description
Combinators to write Show instances.
The following type illustrates the common use cases.
data MyType a
= C a a -- a regular constructor
| a :+: a -- an infix constructor
| R { f1 :: a, f2 :: a } -- a record
infixl 4 :+:
instance Show a => Show (MyType a) where
showsPrec = flip precShows where
precShows (C a b) = showCon "C" @| a @| b
precShows (c :+: d) = showInfix' ":+:" 4 c d
precShows (R {f1 = e, f2 = f}) =
showRecord "R" ("f1" .=. e &| "f2" .=. f)
Synopsis
- class Show a where
- type ShowS = String -> String
- showString :: String -> ShowS
- showParen :: Bool -> ShowS -> ShowS
- showChar :: Char -> ShowS
- shows :: Show a => a -> ShowS
- showListWith :: (a -> ShowS) -> [a] -> ShowS
- type PrecShowS = Int -> ShowS
- showCon :: String -> PrecShowS
- showApp :: PrecShowS -> PrecShowS -> PrecShowS
- (@|) :: Show a => PrecShowS -> a -> PrecShowS
- showInfix :: String -> Int -> PrecShowS -> PrecShowS -> PrecShowS
- showInfix' :: (Show a, Show b) => String -> Int -> a -> b -> PrecShowS
- showInfixl :: String -> Int -> PrecShowS -> PrecShowS -> PrecShowS
- showInfixl' :: (Show a, Show b) => String -> Int -> a -> b -> PrecShowS
- showInfixr :: String -> Int -> PrecShowS -> PrecShowS -> PrecShowS
- showInfixr' :: (Show a, Show b) => String -> Int -> a -> b -> PrecShowS
- type ShowFields = ShowS
- showRecord :: String -> ShowFields -> PrecShowS
- showField :: String -> PrecShowS -> ShowFields
- (.=.) :: Show a => String -> a -> ShowFields
- noFields :: ShowFields
- appendFields :: ShowFields -> ShowFields -> ShowFields
- (&|) :: ShowFields -> ShowFields -> ShowFields
Documentation
Instances
| Show ByteArray | |
| Show Timeout | |
| Show Void | |
| Show CallStack | |
| Show SrcLoc | |
| Show KindRep | |
| Show Module | |
| Show Ordering | |
| Show TrName | |
| Show TyCon | |
| Show TypeLitSort | |
| Show Integer | |
| Show Natural | |
| Show () | |
| Show Bool | |
| Show Char | |
| Show Double | |
| Show Float | |
| Show Int | |
| Show Levity | |
| Show RuntimeRep | |
| Show VecCount | |
| Show VecElem | |
| Show Word | |
| Show a => Show (Complex a) | |
| Show a => Show (First a) | |
| Show a => Show (Last a) | |
| Show a => Show (Max a) | |
| Show a => Show (Min a) | |
| Show m => Show (WrappedMonoid m) | |
| Show a => Show (NonEmpty a) | |
| Show a => Show (Maybe a) | |
| Show a => Show (Solo a) | |
| Show a => Show [a] | |
| HasResolution a => Show (Fixed a) | |
| (Show a, Show b) => Show (Arg a b) | |
| (Show a, Show b) => Show (a, b) | |
| (Show a, Show b, Show c) => Show (a, b, c) | |
| (Show (f a), Show (g a)) => Show (Product f g a) | |
| (Show (f a), Show (g a)) => Show (Sum f g a) | |
| (Show a, Show b, Show c, Show d) => Show (a, b, c, d) | |
| Show (f (g a)) => Show (Compose f g a) | |
| (Show a, Show b, Show c, Show d, Show e) => Show (a, b, c, d, e) | |
| (Show a, Show b, Show c, Show d, Show e, Show f) => Show (a, b, c, d, e, f) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g) => Show (a, b, c, d, e, f, g) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h) => Show (a, b, c, d, e, f, g, h) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i) => Show (a, b, c, d, e, f, g, h, i) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j) => Show (a, b, c, d, e, f, g, h, i, j) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k) => Show (a, b, c, d, e, f, g, h, i, j, k) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l) => Show (a, b, c, d, e, f, g, h, i, j, k, l) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m, Show n) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n) | |
| (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k, Show l, Show m, Show n, Show o) => Show (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) | |
showString :: String -> ShowS #
showListWith :: (a -> ShowS) -> [a] -> ShowS #
type PrecShowS = Int -> ShowS Source #
Type of strings representing expressions, parameterized by the surrounding precedence level.
This is the return type of flip showsPrec
Simple constructors and applications
showCon :: String -> PrecShowS Source #
Show a constructor.
Possible constructor names are:
- regular constructors (e.g.,
"Left"); - parenthesized infix constructors (e.g.,
"(:)"); - smart constructors, for abstract types (e.g.,
"Map.fromList").
Example with smart constructor
Infix constructors
showInfix :: String -> Int -> PrecShowS -> PrecShowS -> PrecShowS Source #
Show an applied infix operator with a given precedence.
Combinators for associative operators
Use with care, see warning under showInfixl.
showInfixl :: String -> Int -> PrecShowS -> PrecShowS -> PrecShowS Source #
Show an applied infix operator which is left associative (infixl).
Use with care.
Warning
This combinator assumes that, if there is another infix operator to the
left, it is either left associative with the same precedence, or it has a
different precedence.
An expression containing two operators at the same level with different
associativities is ambiguous and will not be shown correctly with
showInfixl and showInfixr.
By default, prefer showInfix and showInfix'.
showInfixl' :: (Show a, Show b) => String -> Int -> a -> b -> PrecShowS Source #
Show an applied infix operator which is left associative (infixl).
Use with care, see showInfixl.
This is a shorthand for showInfixl when the arguments types are instances
of Show.
By default, prefer showInfix and showInfix'.
showInfixr :: String -> Int -> PrecShowS -> PrecShowS -> PrecShowS Source #
Show an applied infix operator which is right associative (infixr).
Use with care.
Warning
This combinator assumes that, if there is another infix operator to the
right, it is either right associative with the same precedence, or it has a
different precedence.
An expression containing two operators at the same level with different
associativities is ambiguous and will not be shown correctly with
showInfixl and showInfixr.
By default, prefer showInfix and showInfix'.
Example usage
showList :: Show a => [a] -> PrecShowS showList [] = showCon "[]" showList (x : xs) = showInfixr ":" 5 (flip showsPrec x) (showList xs) -- Example output: -- > 0 : 1 : 2 : 3 : []
showInfixr' :: (Show a, Show b) => String -> Int -> a -> b -> PrecShowS Source #
Show an applied infix operator which is right associative (infixr).
Use with care, see showInfixr.
This is a shorthand for showInfixr when the arguments types are instances
of Show.
By default, prefer showInfix and showInfix'.
Records
type ShowFields = ShowS Source #
Strings representing a set of record fields separated by commas.
They can be constructed using (.=.) and (@|), or using showField and
appendFields.
showRecord :: String -> ShowFields -> PrecShowS Source #
Show a record. The first argument is the constructor name. The second represents the set of record fields.
showField :: String -> PrecShowS -> ShowFields Source #
Show a single record field: a field name and a value separated by '='.
(.=.) :: Show a => String -> a -> ShowFields infixr 8 Source #
noFields :: ShowFields Source #
Empty set of record fields.
appendFields :: ShowFields -> ShowFields -> ShowFields infixr 1 Source #
Separate two nonempty sets of record fields by a comma.
(&|) :: ShowFields -> ShowFields -> ShowFields infixr 1 Source #
An infix synonym of appendFields.