Copyright | (c) The University of Glasgow 2001 |
---|---|
License | BSD-style (see the file libraries/base/LICENSE) |
Maintainer | libraries@haskell.org |
Stability | provisional |
Portability | portable |
Safe Haskell | Safe |
Language | Haskell2010 |
Converting values to readable strings:
the Show
class and associated functions.
Documentation
Conversion of values to readable String
s.
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 thand
(associativity is ignored). Thus, ifd
is0
then the result is never surrounded in parentheses; ifd
is11
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,
produces the stringshow
(Leaf 1 :^: Leaf 2 :^: Leaf 3)"Leaf 1 :^: (Leaf 2 :^: Leaf 3)"
.
:: Int | the operator precedence of the enclosing
context (a number from |
-> a | the value to be converted to a |
-> ShowS |
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.
Instances
Show NestedAtomically Source # | Since: base-4.0 |
Defined in Control.Exception.Base | |
Show NoMatchingContinuationPrompt Source # | Since: base-4.18 |
Defined in Control.Exception.Base | |
Show NoMethodError Source # | Since: base-4.0 |
Defined in Control.Exception.Base | |
Show NonTermination Source # | Since: base-4.0 |
Defined in Control.Exception.Base | |
Show PatternMatchFail Source # | Since: base-4.0 |
Defined in Control.Exception.Base | |
Show RecConError Source # | Since: base-4.0 |
Defined in Control.Exception.Base | |
Show RecSelError Source # | Since: base-4.0 |
Defined in Control.Exception.Base | |
Show RecUpdError Source # | Since: base-4.0 |
Defined in Control.Exception.Base | |
Show TypeError Source # | Since: base-4.9.0.0 |
Show ByteArray Source # | Since: base-4.17.0.0 |
Show Constr Source # | Since: base-4.0.0.0 |
Show ConstrRep Source # | Since: base-4.0.0.0 |
Show DataRep Source # | Since: base-4.0.0.0 |
Show DataType Source # | Since: base-4.0.0.0 |
Show Fixity Source # | Since: base-4.0.0.0 |
Show Dynamic Source # | Since: base-2.1 |
Show All Source # | Since: base-2.1 |
Show Any Source # | Since: base-2.1 |
Show SomeTypeRep Source # | Since: base-4.10.0.0 |
Defined in Data.Typeable.Internal | |
Show Version Source # | Since: base-2.1 |
Show CBool Source # | |
Show CChar Source # | |
Show CClock Source # | |
Show CDouble Source # | |
Show CFloat Source # | |
Show CInt Source # | |
Show CIntMax Source # | |
Show CIntPtr Source # | |
Show CLLong Source # | |
Show CLong Source # | |
Show CPtrdiff Source # | |
Show CSChar Source # | |
Show CSUSeconds Source # | |
Defined in Foreign.C.Types | |
Show CShort Source # | |
Show CSigAtomic Source # | |
Defined in Foreign.C.Types | |
Show CSize Source # | |
Show CTime Source # | |
Show CUChar Source # | |
Show CUInt Source # | |
Show CUIntMax Source # | |
Show CUIntPtr Source # | |
Show CULLong Source # | |
Show CULong Source # | |
Show CUSeconds Source # | |
Show CUShort Source # | |
Show CWchar Source # | |
Show IntPtr Source # | |
Show WordPtr Source # | |
Show Void Source # | Since: base-4.8.0.0 |
Show ByteOrder Source # | Since: base-4.11.0.0 |
Show BlockReason Source # | Since: base-4.3.0.0 |
Defined in GHC.Conc.Sync | |
Show ThreadId Source # | Since: base-4.2.0.0 |
Show ThreadStatus Source # | Since: base-4.3.0.0 |
Defined in GHC.Conc.Sync | |
Show Event Source # | Since: base-4.4.0.0 |
Show Lifetime Source # | Since: base-4.8.1.0 |
Show FdKey Source # | Since: base-4.4.0.0 |
Show ErrorCall Source # | Since: base-4.0.0.0 |
Show ArithException Source # | Since: base-4.0.0.0 |
Defined in GHC.Exception.Type | |
Show SomeException Source # | Since: base-3.0 |
Defined in GHC.Exception.Type | |
Show Fingerprint Source # | Since: base-4.7.0.0 |
Defined in GHC.Fingerprint.Type | |
Show Associativity Source # | Since: base-4.6.0.0 |
Defined in GHC.Generics | |
Show DecidedStrictness Source # | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
Show Fixity Source # | Since: base-4.6.0.0 |
Show SourceStrictness Source # | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
Show SourceUnpackedness Source # | Since: base-4.9.0.0 |
Defined in GHC.Generics | |
Show MaskingState Source # | Since: base-4.3.0.0 |
Show SeekMode Source # | Since: base-4.2.0.0 |
Show CodingFailureMode Source # | Since: base-4.4.0.0 |
Defined in GHC.IO.Encoding.Failure | |
Show CodingProgress Source # | Since: base-4.4.0.0 |
Defined in GHC.IO.Encoding.Types | |
Show TextEncoding Source # | Since: base-4.3.0.0 |
Defined in GHC.IO.Encoding.Types | |
Show AllocationLimitExceeded Source # | Since: base-4.7.1.0 |
Defined in GHC.IO.Exception | |
Show ArrayException Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception | |
Show AssertionFailed Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception | |
Show AsyncException Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception | |
Show BlockedIndefinitelyOnMVar Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception | |
Show BlockedIndefinitelyOnSTM Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception | |
Show CompactionFailed Source # | Since: base-4.10.0.0 |
Defined in GHC.IO.Exception | |
Show Deadlock Source # | Since: base-4.1.0.0 |
Show ExitCode Source # | |
Show FixIOException Source # | Since: base-4.11.0.0 |
Defined in GHC.IO.Exception | |
Show IOErrorType Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception | |
Show IOException Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Exception | |
Show SomeAsyncException Source # | Since: base-4.7.0.0 |
Defined in GHC.IO.Exception | |
Show FD Source # | Since: base-4.1.0.0 |
Show HandlePosn Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Handle | |
Show FileLockingNotSupported Source # | Since: base-4.10.0.0 |
Defined in GHC.IO.Handle.Lock.Common | |
Show BufferMode Source # | Since: base-4.2.0.0 |
Defined in GHC.IO.Handle.Types | |
Show Handle Source # | Since: base-4.1.0.0 |
Show HandleType Source # | Since: base-4.1.0.0 |
Defined in GHC.IO.Handle.Types | |
Show Newline Source # | Since: base-4.3.0.0 |
Show NewlineMode Source # | Since: base-4.3.0.0 |
Defined in GHC.IO.Handle.Types | |
Show IOMode Source # | Since: base-4.2.0.0 |
Show InfoProv Source # | |
Show Int16 Source # | Since: base-2.1 |
Show Int32 Source # | Since: base-2.1 |
Show Int64 Source # | Since: base-2.1 |
Show Int8 Source # | Since: base-2.1 |
Show CCFlags Source # | Since: base-4.8.0.0 |
Show ConcFlags Source # | Since: base-4.8.0.0 |
Show DebugFlags Source # | Since: base-4.8.0.0 |
Defined in GHC.RTS.Flags | |
Show DoCostCentres Source # | Since: base-4.8.0.0 |
Defined in GHC.RTS.Flags | |
Show DoHeapProfile Source # | Since: base-4.8.0.0 |
Defined in GHC.RTS.Flags | |
Show DoTrace Source # | Since: base-4.8.0.0 |
Show GCFlags Source # | Since: base-4.8.0.0 |
Show GiveGCStats Source # | Since: base-4.8.0.0 |
Defined in GHC.RTS.Flags | |
Show IoSubSystem Source # | |
Defined in GHC.RTS.Flags | |
Show MiscFlags Source # | Since: base-4.8.0.0 |
Show ParFlags Source # | Since: base-4.8.0.0 |
Show ProfFlags Source # | Since: base-4.8.0.0 |
Show RTSFlags Source # | Since: base-4.8.0.0 |
Show TickyFlags Source # | Since: base-4.8.0.0 |
Defined in GHC.RTS.Flags | |
Show TraceFlags Source # | Since: base-4.8.0.0 |
Defined in GHC.RTS.Flags | |
Show FractionalExponentBase Source # | |
Show StackEntry Source # | |
Defined in GHC.Stack.CloneStack | |
Show CallStack Source # | Since: base-4.9.0.0 |
Show SrcLoc Source # | Since: base-4.9.0.0 |
Show StaticPtrInfo Source # | Since: base-4.8.0.0 |
Defined in GHC.StaticPtr | |
Show GCDetails Source # | Since: base-4.10.0.0 |
Show RTSStats Source # | Since: base-4.10.0.0 |
Show SomeChar Source # | |
Show SomeSymbol Source # | Since: base-4.7.0.0 |
Defined in GHC.TypeLits | |
Show SomeNat Source # | Since: base-4.7.0.0 |
Show GeneralCategory Source # | Since: base-2.1 |
Defined in GHC.Unicode | |
Show Word16 Source # | Since: base-2.1 |
Show Word32 Source # | Since: base-2.1 |
Show Word64 Source # | Since: base-2.1 |
Show Word8 Source # | Since: base-2.1 |
Show CBlkCnt Source # | |
Show CBlkSize Source # | |
Show CCc Source # | |
Show CClockId Source # | |
Show CDev Source # | |
Show CFsBlkCnt Source # | |
Show CFsFilCnt Source # | |
Show CGid Source # | |
Show CId Source # | |
Show CIno Source # | |
Show CKey Source # | |
Show CMode Source # | |
Show CNfds Source # | |
Show CNlink Source # | |
Show COff Source # | |
Show CPid Source # | |
Show CRLim Source # | |
Show CSocklen Source # | |
Show CSpeed Source # | |
Show CSsize Source # | |
Show CTcflag Source # | |
Show CTimer Source # | |
Show CUid Source # | |
Show Fd Source # | |
Show Timeout Source # | Since: base-4.0 |
Show Lexeme Source # | Since: base-2.1 |
Show Number Source # | Since: base-4.6.0.0 |
Show KindRep Source # | |
Show Module Source # | Since: base-4.9.0.0 |
Show Ordering Source # | Since: base-2.1 |
Show TrName Source # | Since: base-4.9.0.0 |
Show TyCon Source # | Since: base-2.1 |
Show TypeLitSort Source # | Since: base-4.11.0.0 |
Show Integer Source # | Since: base-2.1 |
Show Natural Source # | Since: base-4.8.0.0 |
Show () Source # | Since: base-2.1 |
Show Bool Source # | Since: base-2.1 |
Show Char Source # | Since: base-2.1 |
Show Double Source # | Since: base-2.1 |
Show Float Source # | Since: base-2.1 |
Show Int Source # | Since: base-2.1 |
Show Levity Source # | Since: base-4.15.0.0 |
Show RuntimeRep Source # | Since: base-4.11.0.0 |
Show VecCount Source # | Since: base-4.11.0.0 |
Show VecElem Source # | Since: base-4.11.0.0 |
Show Word Source # | Since: base-2.1 |
Show a => Show (ZipList a) Source # | Since: base-4.7.0.0 |
Show a => Show (And a) Source # | Since: base-4.16 |
Show a => Show (Iff a) Source # | Since: base-4.16 |
Show a => Show (Ior a) Source # | Since: base-4.16 |
Show a => Show (Xor a) Source # | Since: base-4.16 |
Show a => Show (Complex a) Source # | Since: base-2.1 |
Show a => Show (Identity a) Source # | This instance would be equivalent to the derived instances of the
Since: base-4.8.0.0 |
Show a => Show (First a) Source # | Since: base-2.1 |
Show a => Show (Last a) Source # | Since: base-2.1 |
Show a => Show (Down a) Source # | This instance would be equivalent to the derived instances of the
Since: base-4.7.0.0 |
Show a => Show (First a) Source # | Since: base-4.9.0.0 |
Show a => Show (Last a) Source # | Since: base-4.9.0.0 |
Show a => Show (Max a) Source # | Since: base-4.9.0.0 |
Show a => Show (Min a) Source # | Since: base-4.9.0.0 |
Show m => Show (WrappedMonoid m) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Show a => Show (Dual a) Source # | Since: base-2.1 |
Show a => Show (Product a) Source # | Since: base-2.1 |
Show a => Show (Sum a) Source # | Since: base-2.1 |
Show (ConstPtr a) Source # | |
Show a => Show (NonEmpty a) Source # | Since: base-4.11.0.0 |
Show (ForeignPtr a) Source # | Since: base-2.1 |
Defined in GHC.ForeignPtr | |
Show p => Show (Par1 p) Source # | Since: base-4.7.0.0 |
Show (FunPtr a) Source # | Since: base-2.1 |
Show (Ptr a) Source # | Since: base-2.1 |
Show a => Show (Ratio a) Source # | Since: base-2.0.1 |
Show (SChar c) Source # | Since: base-4.18.0.0 |
Show (SSymbol s) Source # | Since: base-4.18.0.0 |
Show (SNat n) Source # | Since: base-4.18.0.0 |
Show a => Show (Maybe a) Source # | Since: base-2.1 |
Show a => Show (a) Source # | Since: base-4.15 |
Show a => Show [a] Source # | Since: base-2.1 |
(Show a, Show b) => Show (Either a b) Source # | Since: base-3.0 |
HasResolution a => Show (Fixed a) Source # | Since: base-2.1 |
Show (Proxy s) Source # | Since: base-4.7.0.0 |
(Show a, Show b) => Show (Arg a b) Source # | Since: base-4.9.0.0 |
Show (TypeRep a) Source # | |
(Ix a, Show a, Show b) => Show (Array a b) Source # | Since: base-2.1 |
Show (U1 p) Source # | Since: base-4.9.0.0 |
Show (V1 p) Source # | Since: base-4.9.0.0 |
Show (ST s a) Source # | Since: base-2.1 |
(Show a, Show b) => Show (a, b) Source # | Since: base-2.1 |
Show (a -> b) Source # | Since: base-2.1 |
Show a => Show (Const a b) Source # | This instance would be equivalent to the derived instances of the
Since: base-4.8.0.0 |
Show (f a) => Show (Ap f a) Source # | Since: base-4.12.0.0 |
Show (f a) => Show (Alt f a) Source # | Since: base-4.8.0.0 |
Show (Coercion a b) Source # | Since: base-4.7.0.0 |
Show (a :~: b) Source # | Since: base-4.7.0.0 |
Show (OrderingI a b) Source # | |
Show (f p) => Show (Rec1 f p) Source # | Since: base-4.7.0.0 |
Show (URec Char p) Source # | Since: base-4.9.0.0 |
Show (URec Double p) Source # | Since: base-4.9.0.0 |
Show (URec Float p) Source # | |
Show (URec Int p) Source # | Since: base-4.9.0.0 |
Show (URec Word p) Source # | Since: base-4.9.0.0 |
(Show a, Show b, Show c) => Show (a, b, c) Source # | Since: base-2.1 |
(Show (f a), Show (g a)) => Show (Product f g a) Source # | Since: base-4.18.0.0 |
(Show (f a), Show (g a)) => Show (Sum f g a) Source # | Since: base-4.18.0.0 |
Show (a :~~: b) Source # | Since: base-4.10.0.0 |
(Show (f p), Show (g p)) => Show ((f :*: g) p) Source # | Since: base-4.7.0.0 |
(Show (f p), Show (g p)) => Show ((f :+: g) p) Source # | Since: base-4.7.0.0 |
Show c => Show (K1 i c p) Source # | Since: base-4.7.0.0 |
(Show a, Show b, Show c, Show d) => Show (a, b, c, d) Source # | Since: base-2.1 |
Show (f (g a)) => Show (Compose f g a) Source # | Since: base-4.18.0.0 |
Show (f (g p)) => Show ((f :.: g) p) Source # | Since: base-4.7.0.0 |
Show (f p) => Show (M1 i c f p) Source # | Since: base-4.7.0.0 |
(Show a, Show b, Show c, Show d, Show e) => Show (a, b, c, d, e) Source # | Since: base-2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f) => Show (a, b, c, d, e, f) Source # | Since: base-2.1 |
(Show a, Show b, Show c, Show d, Show e, Show f, Show g) => Show (a, b, c, d, e, f, g) Source # | Since: base-2.1 |
(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) Source # | Since: base-2.1 |
(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) Source # | Since: base-2.1 |
(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) Source # | Since: base-2.1 |
(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) Source # | Since: base-2.1 |
(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) Source # | Since: base-2.1 |
(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) Source # | Since: base-2.1 |
(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) Source # | Since: base-2.1 |
(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) Source # | Since: base-2.1 |
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.
showListWith :: (a -> ShowS) -> [a] -> ShowS Source #
Show a list (using square brackets and commas), given a function for showing elements.