base-4.9.0.0: Basic libraries

Copyright(c) The University of Glasgow 2001
LicenseBSD-style (see the file libraries/base/LICENSE)
Maintainerlibraries@haskell.org
Stabilityprovisional
Portabilityportable
Safe HaskellSafe
LanguageHaskell2010

Text.Show

Description

Converting values to readable strings: the Show class and associated functions.

Synopsis

Documentation

type ShowS = String -> String Source #

The shows functions return a function that prepends the output String to an existing String. This allows constant-time concatenation of results using function composition.

class Show a where Source #

Conversion of values to readable Strings.

Derived instances of Show have the following properties, which are compatible with derived instances of Read:

  • The result of show is a syntactically correct Haskell expression containing only constants, given the fixity declarations in force at the point where the type is declared. It contains only the constructor names defined in the data type, parentheses, and spaces. When labelled constructor fields are used, braces, commas, field names, and equal signs are also used.
  • If the constructor is defined to be an infix operator, then showsPrec will produce infix applications of the constructor.
  • the representation will be enclosed in parentheses if the precedence of the top-level constructor in x is less than d (associativity is ignored). Thus, if d is 0 then the result is never surrounded in parentheses; if d is 11 it is always surrounded in parentheses, unless it is an atomic expression.
  • If the constructor is defined using record syntax, then show will produce the record-syntax form, with the fields given in the same order as the original declaration.

For example, given the declarations

infixr 5 :^:
data Tree a =  Leaf a  |  Tree a :^: Tree a

the derived instance of Show is equivalent to

instance (Show a) => Show (Tree a) where

       showsPrec d (Leaf m) = showParen (d > app_prec) $
            showString "Leaf " . showsPrec (app_prec+1) m
         where app_prec = 10

       showsPrec d (u :^: v) = showParen (d > up_prec) $
            showsPrec (up_prec+1) u .
            showString " :^: "      .
            showsPrec (up_prec+1) v
         where up_prec = 5

Note that right-associativity of :^: is ignored. For example,

  • show (Leaf 1 :^: Leaf 2 :^: Leaf 3) produces the string "Leaf 1 :^: (Leaf 2 :^: Leaf 3)".

Minimal complete definition

showsPrec | show

Methods

showsPrec :: Int -> a -> ShowS Source #

Convert a value to a readable String.

showsPrec should satisfy the law

showsPrec d x r ++ s  ==  showsPrec d x (r ++ s)

Derived instances of Read and Show satisfy the following:

That is, readsPrec parses the string produced by showsPrec, and delivers the value that showsPrec started with.

show :: a -> String Source #

A specialised variant of showsPrec, using precedence context zero, and returning an ordinary String.

showList :: [a] -> ShowS Source #

The method showList is provided to allow the programmer to give a specialised way of showing lists of values. For example, this is used by the predefined Show instance of the Char type, where values of type String should be shown in double quotes, rather than between square brackets.

Instances

Show Bool # 
Show Char # 
Show Int # 
Show Int8 # 
Show Int16 # 
Show Int32 # 
Show Int64 # 
Show Integer # 
Show Ordering # 
Show Word # 
Show Word8 # 
Show Word16 # 
Show Word32 # 
Show Word64 # 
Show CallStack # 
Show TypeRep # 
Show () # 

Methods

showsPrec :: Int -> () -> ShowS Source #

show :: () -> String Source #

showList :: [()] -> ShowS Source #

Show TyCon # 
Show Module # 
Show TrName # 
Show SrcLoc # 
Show SomeException # 
Show GeneralCategory # 
Show Number # 
Show Lexeme # 
Show IOMode # 
Show SomeSymbol # 
Show SomeNat # 
Show Fingerprint # 
Show ArithException # 
Show ErrorCall # 
Show Dynamic # 
Show IOException # 
Show MaskingState # 
Show DecidedStrictness # 
Show SourceStrictness # 
Show SourceUnpackedness # 
Show Associativity # 
Show Fixity # 
Show Any # 
Show All # 
Show SeekMode # 
Show CUIntMax # 
Show CIntMax # 
Show CUIntPtr # 
Show CIntPtr # 
Show CSUSeconds # 
Show CUSeconds # 
Show CTime # 
Show CClock # 
Show CSigAtomic # 
Show CWchar # 
Show CSize # 
Show CPtrdiff # 
Show CDouble # 
Show CFloat # 
Show CULLong # 
Show CLLong # 
Show CULong # 
Show CLong # 
Show CUInt # 
Show CInt # 
Show CUShort # 
Show CShort # 
Show CUChar # 
Show CSChar # 
Show CChar # 
Show IntPtr # 
Show WordPtr # 
Show CodingProgress # 
Show TextEncoding # 
Show NewlineMode # 
Show Newline # 
Show BufferMode # 
Show Handle # 
Show IOErrorType # 
Show ExitCode # 
Show ArrayException # 
Show AsyncException # 
Show SomeAsyncException # 
Show AssertionFailed # 
Show AllocationLimitExceeded # 
Show Deadlock # 
Show BlockedIndefinitelyOnSTM # 
Show BlockedIndefinitelyOnMVar # 
Show CodingFailureMode # 
Show ThreadStatus # 
Show BlockReason # 
Show ThreadId # 
Show Fd # 
Show CRLim # 
Show CTcflag # 
Show CSpeed # 
Show CCc # 
Show CUid # 
Show CNlink # 
Show CGid # 
Show CSsize # 
Show CPid # 
Show COff # 
Show CMode # 
Show CIno # 
Show CDev # 
Show Lifetime # 
Show Event # 
Show NestedAtomically # 
Show NonTermination # 
Show TypeError # 
Show NoMethodError # 
Show RecUpdError # 
Show RecConError # 
Show RecSelError # 
Show PatternMatchFail # 
Show FdKey # 
Show HandlePosn # 
Show GCStats # 
Show Version # 
Show Fixity # 
Show ConstrRep # 
Show DataRep # 
Show Constr # 
Show DataType # 
Show Void # 
Show Natural # 
Show StaticPtrInfo # 
Show RTSFlags # 
Show TickyFlags # 
Show TraceFlags # 
Show DoTrace # 
Show ProfFlags # 
Show DoHeapProfile # 
Show CCFlags # 
Show DoCostCentres # 
Show DebugFlags # 
Show MiscFlags # 
Show ConcFlags # 
Show GCFlags # 
Show GiveGCStats # 
Show a => Show [a] # 

Methods

showsPrec :: Int -> [a] -> ShowS Source #

show :: [a] -> String Source #

showList :: [[a]] -> ShowS Source #

Show a => Show (Maybe a) # 
Show a => Show (Ratio a) # 
Show (Ptr a) # 

Methods

showsPrec :: Int -> Ptr a -> ShowS Source #

show :: Ptr a -> String Source #

showList :: [Ptr a] -> ShowS Source #

Show (FunPtr a) # 
Show (V1 p) # 

Methods

showsPrec :: Int -> V1 p -> ShowS Source #

show :: V1 p -> String Source #

showList :: [V1 p] -> ShowS Source #

Show (U1 p) # 

Methods

showsPrec :: Int -> U1 p -> ShowS Source #

show :: U1 p -> String Source #

showList :: [U1 p] -> ShowS Source #

Show p => Show (Par1 p) # 

Methods

showsPrec :: Int -> Par1 p -> ShowS Source #

show :: Par1 p -> String Source #

showList :: [Par1 p] -> ShowS Source #

Show a => Show (Down a) # 

Methods

showsPrec :: Int -> Down a -> ShowS Source #

show :: Down a -> String Source #

showList :: [Down a] -> ShowS Source #

Show a => Show (Last a) # 

Methods

showsPrec :: Int -> Last a -> ShowS Source #

show :: Last a -> String Source #

showList :: [Last a] -> ShowS Source #

Show a => Show (First a) # 
Show a => Show (Product a) # 
Show a => Show (Sum a) # 

Methods

showsPrec :: Int -> Sum a -> ShowS Source #

show :: Sum a -> String Source #

showList :: [Sum a] -> ShowS Source #

Show a => Show (Dual a) # 

Methods

showsPrec :: Int -> Dual a -> ShowS Source #

show :: Dual a -> String Source #

showList :: [Dual a] -> ShowS Source #

Show (ForeignPtr a) # 
Show a => Show (ZipList a) # 
Show a => Show (Complex a) # 
HasResolution a => Show (Fixed a) # 
Show a => Show (NonEmpty a) # 
Show a => Show (Option a) # 
Show m => Show (WrappedMonoid m) # 
Show a => Show (Last a) # 

Methods

showsPrec :: Int -> Last a -> ShowS Source #

show :: Last a -> String Source #

showList :: [Last a] -> ShowS Source #

Show a => Show (First a) # 
Show a => Show (Max a) # 

Methods

showsPrec :: Int -> Max a -> ShowS Source #

show :: Max a -> String Source #

showList :: [Max a] -> ShowS Source #

Show a => Show (Min a) # 

Methods

showsPrec :: Int -> Min a -> ShowS Source #

show :: Min a -> String Source #

showList :: [Min a] -> ShowS Source #

Show a => Show (Identity a) #

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed

(Show a, Show b) => Show (Either a b) # 

Methods

showsPrec :: Int -> Either a b -> ShowS Source #

show :: Either a b -> String Source #

showList :: [Either a b] -> ShowS Source #

Show (f p) => Show (Rec1 f p) # 

Methods

showsPrec :: Int -> Rec1 f p -> ShowS Source #

show :: Rec1 f p -> String Source #

showList :: [Rec1 f p] -> ShowS Source #

Show (URec Char p) # 
Show (URec Double p) # 
Show (URec Float p) # 
Show (URec Int p) # 
Show (URec Word p) # 
(Show a, Show b) => Show (a, b) # 

Methods

showsPrec :: Int -> (a, b) -> ShowS Source #

show :: (a, b) -> String Source #

showList :: [(a, b)] -> ShowS Source #

Show (ST s a) # 

Methods

showsPrec :: Int -> ST s a -> ShowS Source #

show :: ST s a -> String Source #

showList :: [ST s a] -> ShowS Source #

Show (Proxy k s) # 

Methods

showsPrec :: Int -> Proxy k s -> ShowS Source #

show :: Proxy k s -> String Source #

showList :: [Proxy k s] -> ShowS Source #

(Show a, Show b) => Show (Arg a b) # 

Methods

showsPrec :: Int -> Arg a b -> ShowS Source #

show :: Arg a b -> String Source #

showList :: [Arg a b] -> ShowS Source #

Show c => Show (K1 i c p) # 

Methods

showsPrec :: Int -> K1 i c p -> ShowS Source #

show :: K1 i c p -> String Source #

showList :: [K1 i c p] -> ShowS Source #

(Show (f p), Show (g p)) => Show ((:+:) f g p) # 

Methods

showsPrec :: Int -> (f :+: g) p -> ShowS Source #

show :: (f :+: g) p -> String Source #

showList :: [(f :+: g) p] -> ShowS Source #

(Show (f p), Show (g p)) => Show ((:*:) f g p) # 

Methods

showsPrec :: Int -> (f :*: g) p -> ShowS Source #

show :: (f :*: g) p -> String Source #

showList :: [(f :*: g) p] -> ShowS Source #

Show (f (g p)) => Show ((:.:) f g p) # 

Methods

showsPrec :: Int -> (f :.: g) p -> ShowS Source #

show :: (f :.: g) p -> String Source #

showList :: [(f :.: g) p] -> ShowS Source #

(Show a, Show b, Show c) => Show (a, b, c) # 

Methods

showsPrec :: Int -> (a, b, c) -> ShowS Source #

show :: (a, b, c) -> String Source #

showList :: [(a, b, c)] -> ShowS Source #

Show ((:~:) k a b) # 

Methods

showsPrec :: Int -> (k :~: a) b -> ShowS Source #

show :: (k :~: a) b -> String Source #

showList :: [(k :~: a) b] -> ShowS Source #

Show (Coercion k a b) # 

Methods

showsPrec :: Int -> Coercion k a b -> ShowS Source #

show :: Coercion k a b -> String Source #

showList :: [Coercion k a b] -> ShowS Source #

Show (f a) => Show (Alt k f a) # 

Methods

showsPrec :: Int -> Alt k f a -> ShowS Source #

show :: Alt k f a -> String Source #

showList :: [Alt k f a] -> ShowS Source #

Show a => Show (Const k a b) #

This instance would be equivalent to the derived instances of the Const newtype if the runConst field were removed

Methods

showsPrec :: Int -> Const k a b -> ShowS Source #

show :: Const k a b -> String Source #

showList :: [Const k a b] -> ShowS Source #

Show (f p) => Show (M1 i c f p) # 

Methods

showsPrec :: Int -> M1 i c f p -> ShowS Source #

show :: M1 i c f p -> String Source #

showList :: [M1 i c f p] -> ShowS Source #

(Show a, Show b, Show c, Show d) => Show (a, b, c, d) # 

Methods

showsPrec :: Int -> (a, b, c, d) -> ShowS Source #

show :: (a, b, c, d) -> String Source #

showList :: [(a, b, c, d)] -> ShowS Source #

(Show1 f, Show1 g, Show a) => Show (Product * f g a) # 

Methods

showsPrec :: Int -> Product * f g a -> ShowS Source #

show :: Product * f g a -> String Source #

showList :: [Product * f g a] -> ShowS Source #

(Show1 f, Show1 g, Show a) => Show (Sum * f g a) # 

Methods

showsPrec :: Int -> Sum * f g a -> ShowS Source #

show :: Sum * f g a -> String Source #

showList :: [Sum * f g a] -> ShowS Source #

(Show a, Show b, Show c, Show d, Show e) => Show (a, b, c, d, e) # 

Methods

showsPrec :: Int -> (a, b, c, d, e) -> ShowS Source #

show :: (a, b, c, d, e) -> String Source #

showList :: [(a, b, c, d, e)] -> ShowS Source #

(Show1 f, Show1 g, Show a) => Show (Compose * * f g a) # 

Methods

showsPrec :: Int -> Compose * * f g a -> ShowS Source #

show :: Compose * * f g a -> String Source #

showList :: [Compose * * f g a] -> ShowS Source #

(Show a, Show b, Show c, Show d, Show e, Show f) => Show (a, b, c, d, e, f) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f) -> ShowS Source #

show :: (a, b, c, d, e, f) -> String Source #

showList :: [(a, b, c, d, e, f)] -> ShowS Source #

(Show a, Show b, Show c, Show d, Show e, Show f, Show g) => Show (a, b, c, d, e, f, g) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g) -> ShowS Source #

show :: (a, b, c, d, e, f, g) -> String Source #

showList :: [(a, b, c, d, e, f, g)] -> ShowS Source #

(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) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h) -> ShowS Source #

show :: (a, b, c, d, e, f, g, h) -> String Source #

showList :: [(a, b, c, d, e, f, g, h)] -> ShowS Source #

(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) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i) -> ShowS Source #

show :: (a, b, c, d, e, f, g, h, i) -> String Source #

showList :: [(a, b, c, d, e, f, g, h, i)] -> ShowS Source #

(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) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j) -> ShowS Source #

show :: (a, b, c, d, e, f, g, h, i, j) -> String Source #

showList :: [(a, b, c, d, e, f, g, h, i, j)] -> ShowS Source #

(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) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k) -> ShowS Source #

show :: (a, b, c, d, e, f, g, h, i, j, k) -> String Source #

showList :: [(a, b, c, d, e, f, g, h, i, j, k)] -> ShowS Source #

(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) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k, l) -> ShowS Source #

show :: (a, b, c, d, e, f, g, h, i, j, k, l) -> String Source #

showList :: [(a, b, c, d, e, f, g, h, i, j, k, l)] -> ShowS Source #

(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) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k, l, m) -> ShowS Source #

show :: (a, b, c, d, e, f, g, h, i, j, k, l, m) -> String Source #

showList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m)] -> ShowS Source #

(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) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> ShowS Source #

show :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n) -> String Source #

showList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] -> ShowS Source #

(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) # 

Methods

showsPrec :: Int -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> ShowS Source #

show :: (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) -> String Source #

showList :: [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] -> ShowS Source #

shows :: Show a => a -> ShowS Source #

equivalent to showsPrec with a precedence of 0.

showChar :: Char -> ShowS Source #

utility function converting a Char to a show function that simply prepends the character unchanged.

showString :: String -> ShowS Source #

utility function converting a String to a show function that simply prepends the string unchanged.

showParen :: Bool -> ShowS -> ShowS Source #

utility function that surrounds the inner show function with parentheses when the Bool parameter is True.

showListWith :: (a -> ShowS) -> [a] -> ShowS Source #

Show a list (using square brackets and commas), given a function for showing elements.