Safe Haskell | Safe |
---|---|
Language | Haskell2010 |
Data.Universe.Instances.Show
Contents
- class Show a where
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)"
.
Methods
showsPrec :: Int -> 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 Bool | |
Show Char | |
Show Int | |
Show Integer | |
Show Ordering | |
Show Word | |
Show CallStack | |
Show () | |
Show TyCon | |
Show Module | |
Show TrName | |
Show Version | |
Show All | |
Show Any | |
Show Fixity | |
Show Associativity | |
Show SourceUnpackedness | |
Show SourceStrictness | |
Show DecidedStrictness | |
Show SrcLoc | |
Show a => Show [a] | |
Show a => Show (Maybe a) | |
Show (Ptr a) | |
Show (FunPtr a) | |
Show (V1 p) | |
Show (U1 p) | |
Show p => Show (Par1 p) | |
Show a => Show (ZipList a) | |
Show a => Show (Dual a) | |
Show a => Show (Sum a) | |
Show a => Show (Product a) | |
Show a => Show (First a) | |
Show a => Show (Last a) | |
(Show b, Show a) => Show (Either a b) | |
Show (f p) => Show (Rec1 f p) | |
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) | |
Show (Proxy k s) | |
(Show k, Show a) => Show (Map k a) | |
Show c => Show (K1 i c p) | |
(Show (g p), Show (f p)) => Show ((:+:) f g p) | |
(Show (g p), Show (f p)) => Show ((:*:) f g p) | |
Show (f (g p)) => Show ((:.:) f g p) | |
(Show a, Show b, Show c) => Show (a, b, c) | |
Show (f a) => Show (Alt k f a) | |
Show (f p) => Show (M1 i c f p) | |
(Show a, Show b, Show c, Show d) => Show (a, b, c, d) | |
(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) | |